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ABASTITIES AND CHROMOSOME ABNOARMALITIES
2
.
1
ab
ortion
2
.
1
.
1
De
finition
Ab
ormus is
a
t
e
rmin
a
tion of pr
e
gn
a
n
c
y
be
for
e
th
e
f
e
tus
ca
n liv
e
outsi
de
th
e
ut
e
rus
,
or
be
for
e a
g
e
st
a
tion
a
l
a
g
e
r
eac
h
e
s
20
w
ee
ks
(
ca
l
c
ul
a
t
ed
from th
e
first
da
y of th
e
l
a
st m
e
nstru
a
tion
)
or f
e
t
a
l w
e
ight is l
e
ss th
a
n
500
gr
a
ms
.
A
noth
e
r
de
finition st
a
t
e
s
th
a
t
ab
ortion is t
e
rmin
a
tion of pr
e
gn
a
n
c
y
be
for
e
th
e a
g
e
of
16
w
ee
ks wh
e
n
pl
a
n
e
t
a
tion h
a
s not
bee
n
c
ompl
e
t
ed
.
Acc
or
d
ing to
Ea
stm
a
n
a
n
d c
oll
ea
gu
e
s
,
ab
ortion is
a
t
e
rmin
a
tion of pr
e
gn
a
n
c
y wh
e
n th
e
f
e
tus h
a
s not
bee
n
ab
l
e
to surviv
e
outsi
de
th
e
ut
e
rus
,
w
e
ighing
be
tw
ee
n
400
-
1000
gr
a
ms or
a
g
e
st
a
tion of l
e
ss th
a
n
28
w
ee
ks
.
I
n
1977
,
WHO
(
W
orl
d Hea
lth
O
rg
a
niz
a
tion
)
de
fin
e
s
ab
ortion
a
s th
e e
xit of
th
e
f
e
tus from th
e
ut
e
rus with
a
w
e
ight of l
e
ss th
a
n
500
gr
a
ms or
a
g
e
st
a
tion of
20
-
22
w
ee
ks
.
M
is
ca
rri
a
g
e
is on
e
of th
e
most
c
ommon pr
e
gn
a
n
c
y
c
ompli
ca
tions
,
with
15
%
of
pr
e
gn
a
n
c
y
e
n
d
ing with
a
mis
ca
rri
a
g
e
.
T
h
e
r
ea
son
ca
n
be
in th
e
form of g
e
n
e
ti
c
f
ac
tors or
ab
norm
a
l f
e
t
a
l
de
v
e
lopm
e
nt
.
Re
p
ea
t
ed
mis
ca
rri
a
g
e
s o
cc
ur in
3
%
of
pr
e
gn
a
nt wom
e
n popul
a
tions
a
n
d a
sso
c
i
a
t
ed
with throm
b
ophili
a
,
ce
rvi
ca
l
w
ea
kn
e
ss
e
s
,
inf
ec
tions
,
e
n
d
o
c
rin
e ab
norm
a
liti
e
s
,
a
n
a
tomi
ca
l f
ac
tors
,
a
n
d
immun
e
ab
norm
a
liti
e
s
.
Ba
s
ed
on th
e
history of pr
e
gn
a
n
c
y
,
th
e
r
e a
r
e
thr
ee
groups of wom
e
n who h
a
v
e a
risk of mis
ca
rri
a
g
e
,
n
a
m
e
ly
:
1
.
G
roup of prim
a
ry r
ec
urr
e
nt mis
ca
rri
a
g
e
:
T
his group
c
onsists of wom
e
n who
e
xp
e
ri
e
n
ce
thr
ee
or mor
e c
ons
ec
utiv
e
mis
ca
rri
a
g
e
s without pr
e
gn
a
n
c
y surviving for
mor
e
th
a
n
20
w
ee
ks
.
2
.
Sec
on
da
ry r
ec
urring mis
ca
rri
a
g
e
group
:
T
his group in
c
lu
de
s wom
e
n who
e
xp
e
ri
e
n
ce
thr
ee
or mor
e
mis
ca
rri
a
g
e
s
a
ft
e
r
a
t l
ea
st on
e
pr
e
gn
a
n
c
y th
a
t surviv
e
s
mor
e
th
a
n
20
w
ee
ks
,
whi
c
h m
a
y
e
n
d
up with liv
e b
irth
,
dea
th
,
or
dea
th of n
e
w
b
orns
.
3
.
T
h
e
r
ec
urr
e
nt mis
ca
rri
a
g
e
group
Te
rti
a
ry
:
T
his group
c
onsists of wom
e
n who
e
xp
e
ri
e
n
ced a
t l
ea
st thr
ee
in
c
on
a
t
e
mis
ca
rri
a
g
e
s
a
n
d
int
e
rsp
e
rs
ed
with pr
e
gn
a
n
c
y
th
a
t surviv
ed
mor
e
th
a
n
20
w
ee
ks
.
A
wom
a
n
ca
n
e
xp
e
ri
e
n
ce a
mis
ca
rri
a
g
e
r
e
p
ea
t with on
e
m
a
n
b
ut not with
a
noth
e
r
m
a
n
.
T
h
e a
g
e
of ol
de
r wom
e
n is
a
risk f
ac
tor of mis
ca
rri
a
g
e
;
T
his risk in
c
r
ea
s
e
s with
th
e a
g
e
of m
a
t
e
rn
a
l
a
g
e
,
e
sp
ec
i
a
lly
a
ft
e
r th
e a
g
e
of
35
y
ea
rs
.
2
.
1
.
2
ab
ortion
c
lini
c
st
ad
ium
:
1
.
Ab
otor
I
mmin
e
ns
(
T
hr
ea
t of mis
ca
rri
a
g
e
)
is th
e
in
c
i
de
n
ce
of
b
l
eed
ing from th
e
ut
e
rus in pr
e
gn
a
n
c
y
be
for
e
20
w
ee
ks
,
wh
e
r
e
th
e c
on
ce
ption is still in th
e
wom
b
,
still
a
liv
e
,
without
ce
rvi
ca
l
d
il
a
tion
,
a
n
d
pr
e
gn
a
n
c
y
ca
n still
be
m
a
int
a
in
ed
.
2
.
Ab
otor insipi
e
ns
(
in
e
vit
ab
l
e
mis
ca
rri
a
g
e
)
is th
e
in
c
i
de
n
ce
of ut
e
rin
e b
l
eed
ing in
pr
e
gn
a
n
c
y
be
for
e
20
w
ee
ks wh
e
r
e
pr
e
gn
a
n
c
y
ca
nnot
be
m
a
int
a
in
ed a
nymor
e
,
with
ce
rvi
ca
l ut
e
rus h
a
s
bee
n
d
il
a
t
ed
,
b
ut th
e c
on
ce
ption r
e
sults
a
r
e
still in th
e
wom
b
.
E
xp
e
n
d
itur
e
s of
c
on
ce
ption must
be d
on
e
imm
ed
i
a
t
e
ly with
d
il
a
t
a
tion
a
n
d c
ur
e
tt
a
g
e
.
3
.
I
n
c
omplitus
ab
ortion is
a
p
a
rti
a
l
e
xp
e
n
d
itur
e
of th
e c
on
ce
ption of th
e
ut
e
rus in
pr
e
gn
a
n
c
y
be
for
e
20
w
ee
ks
,
wh
e
r
e
th
e
r
e
is th
e
r
e
m
a
ining n
e
twork of
c
on
ce
ption
(
pl
ace
nt
a
)
l
e
ft in th
e
wom
b
,
ca
using th
e c
ontr
ac
tion of th
e
ut
e
rus
acc
omp
a
ni
ed b
y
p
a
in
a
n
d b
l
eed
ing ut
e
rin
e
.
E
xp
e
n
d
itur
e
s
Re
si
d
u
a
l r
e
sults must
be ca
rri
ed
out
imm
ed
i
a
t
e
ly with
d
il
a
t
a
tion
a
n
d c
ur
e
tt
a
g
e
.
4
.
C
ompl
e
t
e ab
ortion is th
e e
xp
e
n
d
itur
e
of
a
ll th
e
r
e
sults of th
e c
on
ce
ption of th
e
ut
e
rus in pr
e
gn
a
n
c
y
be
for
e
20
w
ee
ks
.
2
.
1
.
3
Pa
thophysiology
:
W
h
e
n sp
e
rm
a
tozo
a
p
e
n
e
tr
a
t
e
s th
e
p
e
lusi
da
zon
e
,
a
r
eac
tion o
cc
urs in th
e
ovum
c
ort
e
x
.
T
h
e c
ort
e
x gr
a
nul
e
s in ovum or s
ec
on
da
ry oo
c
yt
e
s fun
c
tion with pl
a
sm
a ce
ll
m
e
m
b
r
a
n
e
s
,
so th
e e
nzym
e
s in th
e
gr
a
nul
e
s
a
r
e
r
e
l
ea
s
ed
through th
e e
xo
c
ytosis to
th
e
p
e
lusi
da
zon
e
.
T
his
ca
us
e
s gly
c
oprot
e
in in th
e
p
e
lusi
da
zon
e
to
b
in
d
to form
h
a
r
d
m
a
t
e
ri
a
l
a
n
d ca
nnot
be
p
e
n
e
tr
a
t
ed b
y oth
e
r sp
e
rm
a
tozo
a
.
B
oth
P
ronu
c
l
e
us
a
ppro
ac
h
ed a
n
d
form
ed a
zygot
e c
onsisting of m
a
l
e a
n
d
f
e
m
a
l
e
g
e
n
e
ti
c
m
a
t
e
ri
a
ls
.
I
n hum
a
ns
,
th
e
r
e a
r
e
46
c
hromosom
e
s
,
n
a
m
e
ly
44
a
utosom
a
l
c
hromosom
e
s
a
n
d
2
g
e
nit
a
l
c
hromosom
e
s
.
A
f
e
w hours
a
ft
e
r f
e
rtiliz
a
tion
,
Z
igot
be
g
a
n to
d
ivi
de
.
T
his o
cc
urs
beca
us
e
th
e
ovum
c
ytopl
a
sm
c
ont
a
ins
a
lot of
a
mino
ac
i
d
s
a
n
d e
nzym
e
s
.
I
n thr
ee da
ys
,
th
e
s
a
m
e
l
a
rg
e ce
ll group w
a
s form
ed
,
a
n
d
th
e
r
e
sults of th
e c
on
ce
ption w
e
r
e
in th
e
morul
a
st
a
g
e
wh
e
r
e d
ivisions o
cc
urr
ed
from
vit
e
lus to vit
e
lus volum
e
r
ed
u
ced a
n
d
fill
ed
with morul
a
.
O
n th
e
fourth
da
y
,
th
e c
on
ce
ption of r
eac
hing th
e B
l
a
stul
a
st
a
g
e ca
ll
ed B
l
a
stokist
a
,
wh
e
r
e
th
e e
xt
e
rior is
a
tropho
b
l
a
st n
e
twork
a
n
d
th
e
insi
de
is
ca
ll
ed
th
e
m
a
ss
ce
ll
m
a
ss in on
e
pol
e
.
B
l
a
stokist
a
is
e
m
bedded be
tw
ee
n th
e
ut
e
rin
e
mu
c
ous
e
pith
e
li
a
l
ce
ll tissu
e
on th
e
6
th to
7
th
da
y
a
ft
e
r ovul
a
tion
,
a
n
d
th
e
n
d
iff
e
r
e
nti
a
tion is
a
syn
c
i
a
l
m
a
ss
.
O
n th
e
8
th
da
y
,
th
e
tropho
b
l
a
st
d
iff
e
rs into th
e
out
e
r l
a
y
e
r
(
sintitiotrofo
b
l
a
st
)
a
n
d
th
e
inn
e
r l
a
y
e
r
(
sitosito
T
rofo
B
l
a
st
).
T
h
e
syn
c
i
a
l m
a
ss th
e
n p
e
n
e
tr
a
t
e
s
e
pith
e
li
a
l
ce
lls
a
n
d
spr
ead
s to th
e
strom
a
.
O
n th
e
9
th
da
y
,
Va
muol
e
s or
La
kun
a a
pp
ea
r
ed
on
th
e
syn
c
i
a
l
,
e
nl
a
rg
ed
,
a
n
d
unit
ed
.
T
h
e
form
a
tion of ut
e
ropl
a
sti
c c
ir
c
ul
a
tion o
cc
urs wh
e
n th
e
moth
e
r
'
s v
e
nous
ca
pill
a
ry
c
om
e
s into
a
syn
c
i
a
l
,
a
llows
b
loo
d
to flow through th
e
syst
e
m
.
La
kun
a
will
be a
n
int
e
rvilus
a
r
ea
of th
e
pl
ace
nt
a
.
O
n
12
th to
13
th
da
y
a
ft
e
r f
e
rtiliz
a
tion
,
th
e b
l
a
sto
c
ist
a
w
a
s fully
a
tt
ac
h
ed
to th
e dec
i
d
u
a
strom
a
,
so th
e
ut
e
rin
e
surf
ace e
pith
e
lium
c
ontinu
ed
to grow
.
T
his in
d
i
ca
t
e
s th
e
initi
a
l st
a
g
e
of impl
a
nt
a
tion
acc
omp
a
ni
ed b
y
a
littl
e
n
ec
rosis or infl
a
mm
a
tory r
eac
tion from th
e
mu
c
ous tissu
e
.
A
ft
e
r th
e
initi
a
l
ph
a
s
e
of ni
da
tion
,
th
e
tropho
b
l
a
st
d
iff
e
r
e
nti
a
tion o
cc
urs in two m
a
in lin
e
s
,
n
a
m
e
ly
V
illous
a
n
d E
xtr
a V
illous
,
eac
h with
a d
iff
e
r
e
nt fun
c
tion
.
V
illus tropho
b
l
a
st
c
ov
e
r
ed
th
e e
ntir
e
villi
a
l pl
ace
nt
a c
hori
a
l
a
n
d
fun
c
tions to tr
a
nsport nutri
e
nts
a
n
d
oxyg
e
n
from th
e
moth
e
r to th
e
f
e
tus
.
I
n two w
ee
ks th
e de
v
e
lopm
e
nt of th
e c
on
ce
ption
,
th
e
inv
a
siv
e
tropho
b
l
a
sts
p
e
n
e
tr
a
t
e
th
e e
n
d
om
e
tri
a
l
b
loo
d
v
e
ss
e
ls
a
n
d
form int
e
rtropho
b
l
a
sti
c
sinus
e
s th
a
t
c
ont
a
in m
a
t
e
rn
a
l
b
loo
d
.
T
h
e
f
e
t
a
l
b
loo
d c
ir
c
ul
a
tion
e
n
d
s in th
e ca
pill
a
ry
c
urt
a
in in
th
e c
hori
a
l vili
e
nt whos
e
int
e
rv
a
l sp
ace
is fill
ed
with m
a
t
e
rn
a
l
b
loo
d
from th
e a
rt
e
ry
of th
e
spir
a
lis
a
n
d
is issu
ed
through th
e
ut
e
rin
e
v
e
in
.
V
ili
C
ori
a
lis grows into
a
m
a
ss
of
a
n
e
twork
ca
ll
ed
th
e
pl
ace
nt
a
.
T
h
e
r
e
sults of th
e c
on
ce
ption
a
r
e e
nv
e
lop
ed b
y
th
e
jonjot
-
jonjot
ca
ll
ed V
ili
C
ori
a
lis
a
n
d
r
e
l
a
t
e
s to
K
orion
.
T
h
e K
orion form
ed
from
a
c
orioni
ca
l m
e
m
b
r
a
n
e
,
a
n
d V
ili
C
ori
a
lis r
e
l
a
t
ed
to th
e de
si
d
u
a ba
s
a
lis growing
a
n
d
b
r
a
n
c
h
ed
w
e
ll
,
so th
a
t this
K
orion is
ca
ll
ed
th
e
fron
d
osum korion
.
M
oth
e
r
'
s
a
n
d
f
e
t
a
l
b
loo
d
is s
e
p
a
r
a
t
ed b
y f
e
t
a
l
b
loo
d
v
e
ss
e
ls
a
n
d a c
horion l
a
y
e
r
.
I
t w
a
s r
e
v
ea
l
ed
th
a
t th
e
o
cc
urr
e
n
ce
of throm
b
osis in th
e
ut
e
ropl
a
sti
ca
l
b
loo
d
v
e
ss
e
ls
woul
d d
istur
b
p
e
rfusion to th
e
pl
ace
nt
a
.
Fa
ilur
e
to
e
n
d
ov
a
s
c
ul
a
r
a
n
d
int
e
rstiti
a
l in
th
e d
iff
e
r
e
nti
a
tion of
e
xtr
a
villus tropho
b
l
a
s
ca
n
ca
us
e ab
ortion
a
t th
e be
ginning of
pr
e
gn
a
n
c
y
.
I
n oth
e
r
ca
s
e
s spont
a
n
e
ous
ab
ortion
a
t th
e be
ginning of pr
e
gn
a
n
c
y
,
th
e
tropho
b
l
a
st
e
xtr
a
villus syn
cS
iti
a
l
d
o
e
s not r
eac
h th
e
spir
a
l
a
rt
e
ry
.
T
his r
e
sult
ed
in
th
e a
rt
e
ri
e
s of not pulping
a
n
d b
loo
d
supply through th
e
spir
a
l
a
rt
e
ry woul
d
not
be
ade
qu
a
t
e
until th
e e
n
d
of th
e
first trim
e
st
e
r
,
whi
c
h l
ed
to spont
a
n
e
ous
ab
ortion
.
2
.
1
.
4
e
tiology
M
or
e
th
a
n
80
%
of
ca
s
e
s of mis
ca
rri
a
g
e
s o
cc
ur
a
t
12
w
ee
ks of g
e
st
a
tion
,
a
ft
e
r th
a
t
th
e
in
c
i
de
n
ce
h
a
s
dec
lin
ed
qui
c
kly
(
Ha
rl
a
p
&
S
hiono
,
1980
).
C
hromosom
e
ab
norm
a
liti
e
s
a
r
e
th
e
m
a
in
ca
us
e
of this
ea
rly mis
ca
rri
a
g
e ca
s
e
,
a
n
d a
ft
e
r th
a
t th
e
in
c
i
de
n
ce a
lso
dec
r
ea
s
e
s
.
T
h
e
risk of mis
ca
rri
a
g
e
in
c
r
ea
s
e
s with th
e
in
c
r
ea
sing
p
a
rity
a
n
d a
g
e
of moth
e
rs
a
n
d
f
a
th
e
r
.
T
h
e e
x
ac
t m
ec
h
a
nism of mis
ca
rri
a
g
e
s is not
a
lw
a
ys
c
l
ea
r
,
b
ut in th
e ea
rly months of
pr
e
gn
a
n
c
y
,
spont
a
n
e
ous ovum
e
xp
e
n
d
itur
e
is
a
lmost
a
lw
a
ys pr
eceded b
y th
e dea
th
of th
e e
m
b
ryo or f
e
tus
.
T
h
e
r
e
for
e
,
th
e c
onsi
de
r
a
tion of
e
tiology in
ea
rly
mis
ca
rri
a
g
e
s
,
a
mong oth
e
rs
,
in
c
lu
de
s
c
onsumption of th
e ca
us
e
of f
e
t
a
l
dea
th
.
I
n
th
e
following months
,
th
e
f
e
tus oft
e
n h
a
s not
d
i
ed
in th
e
ut
e
rus
be
for
e e
xp
e
n
d
itur
e
a
n
d
th
e ca
us
e
of th
e e
xp
e
n
d
itur
e
n
eed
to
be
stu
d
i
ed
.
1
.
Fe
t
a
l f
ac
tor
:
a
.
Ab
norm
a
l
Z
igot
De
v
e
lopm
e
nt
b
r
ea
kf
a
st
.
A
n
e
uploi
d
i
C
..
E
uploi
d
d
.
T
risomy
A
utosom
He
y
.
M
onosomy x
f
.
C
hromosom
e
stru
c
tur
a
l
ab
norm
a
liti
e
s
2
.
M
oth
e
r f
ac
tor
:
a
.
A
g
e
b
r
ea
kf
a
st
.
I
nf
ec
tion
:
T
or
c
h
,
C
hl
a
my
d
i
a T
r
ac
hom
a
tis
C
..
C
hroni
c d
is
ea
s
e
:
TB
,
ca
r
c
inom
a
d
.
E
n
d
o
c
rinologi
ca
l
ab
norm
a
liti
e
s
:
DM
,
prog
e
st
e
ron
e de
fi
c
i
e
n
c
y
He
y
.
Ma
lnutrition
f
.
Rad
i
a
tion
g
.
S
moking
,
ca
ff
e
in
e
h
.
T
r
a
um
a
I
.
La
p
a
rotomy
a
.
U
t
e
rin
e
stru
c
tur
e ab
norm
a
liti
e
s
k
.
A
utoimmun
e D
is
ea
s
e
:
SLE
(
S
yst
e
mi
c L
upus
E
ryth
e
m
a
tosus
),
ACA
(
A
nti
b
o
d
i
A
nti
ca
r
d
iolipin
)
l
.
Ab
norm
a
l immun
e
r
e
spons
e
a
m
.
E
nvironm
e
nt
a
l toxin
3
.
Fa
th
e
r
'
s f
ac
tor
2
.
1
.
5
in
c
i
de
n
ce
I
n
I
n
d
on
e
si
a
,
it is
e
stim
a
t
ed
th
a
t
a
roun
d
10
-
15
%
of
a
ll pr
e
gn
a
n
c
i
e
s h
a
v
e
spont
a
n
e
ous
ab
ortion
.
Acc
or
d
ing to th
e
offi
c
i
a
l
WHO da
t
a
(
1994
),
spont
a
n
e
ous
ab
ortion w
a
s r
e
port
ed
to o
cc
ur
a
t
10
%
of
a
ll pr
e
gn
a
n
c
i
e
s
.
M
or
e
th
a
n
80
%
of
ca
s
e
s
of spont
a
n
e
ous
ab
ortion o
cc
ur in th
e
first trim
e
st
e
r of pr
e
gn
a
n
c
y
a
n
d
this in
c
i
de
n
ce
will
dec
r
ea
s
e
signifi
ca
ntly
a
ft
e
r th
a
t
.
De
t
e
rmining th
e
in
c
i
de
n
ce
of spont
a
n
e
ous
ab
ortion is quit
e d
iffi
c
ult
beca
us
e
m
a
ny
provok
a
tus
ab
or
a
t
e
s
a
r
e
not r
e
port
ed
,
unl
e
ss
c
ompli
ca
tions o
cc
ur
.
S
pont
a
n
e
ous
ab
ortion th
a
t is not
c
l
ea
r th
e a
g
e
of pr
e
gn
a
n
c
y only giv
e
s littl
e
symptoms or signs
so th
a
t th
e
moth
e
r usu
a
lly
d
o
e
s not s
ee
k tr
ea
tm
e
nt
.
F
rom known
e
v
e
nts
,
a
roun
d
15
-
20
%
a
r
e
spont
a
n
e
ous
ab
ortion
.
Ab
out
5
%
of
c
oupl
e
s who try to g
e
t pr
e
gn
a
nt will
e
xp
e
ri
e
n
ce
r
ec
urring mis
ca
rri
a
g
e
s
,
a
n
d ab
out
1
%
of th
e c
oupl
e e
xp
e
ri
e
n
ce
thr
ee
or
mor
e
r
ec
urr
e
nt mis
ca
rri
a
g
e
s
.
M
ost stu
d
i
e
s st
a
t
e
th
a
t th
e
in
c
i
de
n
ce
of spont
a
n
e
ous
ab
ortion r
a
ng
e
s from
15
-
20
%
of
a
ll pr
e
gn
a
n
c
i
e
s
.
W
h
e
n furth
e
r r
e
s
ea
r
c
h
ed
,
th
e
in
c
i
de
n
ce
of spont
a
n
e
ous
ab
ortion
ca
n
be c
los
e
to
50
%
.
T
his is
d
u
e
to th
e
high num
be
r of mis
ca
rri
a
g
e
s in
c
h
e
mi
ca
l
pr
e
gn
a
n
c
i
e
s th
a
t
a
r
e
not
de
t
ec
t
ed a
t
2
-
4
w
ee
ks
a
ft
e
r
c
on
ce
ption
.
M
ost of th
e
s
e
pr
e
gn
a
n
c
y f
a
ilur
e
s
a
r
e ca
us
ed b
y g
a
m
e
t f
a
ilur
e
.
S
ofi
a D
ori
a a
n
d
h
e
r
c
oll
ea
gu
e
s
(
2008
)
r
e
port
ed
th
a
t of
232
p
a
ti
e
nts
d
i
a
gnos
ed
with
spont
a
n
e
ous
ab
ortion
,
147
(
63
.
4
%
)
ca
s
e
s h
ad
norm
a
l
c
hromosom
e
s
,
whil
e
85
(
36
.
6
%
)
h
ad ab
norm
a
l
c
hromosom
e
s
.
O
f th
e
85
ca
s
e
s of
c
hromosom
e ab
norm
a
liti
e
s
,
81
(
95
.
3
%
)
o
cc
urr
ed
in th
e
first trim
e
st
e
r
,
2
(
2
.
4
%
)
in th
e
s
ec
on
d
trim
e
st
e
r
,
a
n
d
2
(
2
.
4
%
)
in th
e
thir
d
trim
e
st
e
r
.
O
f th
e
66
ca
s
e
s of spont
a
n
e
ous
ab
ortion
c
on
d
u
c
t
ed b
y
k
a
riotip
e
x
a
min
a
tion
,
62
/
66
(
93
.
9
%
)
show
ed ab
norm
a
liti
e
s
;
36
/
62
with
a
singl
e
trisomy
,
5
/
62
with two or thr
ee
trisomy
,
6
/
62
with
a
monosomy
X
,
13
/
62
with
polypoi
d
i
,
9
/
62
with mos
a
i
c
s
,
a
n
d
1
/
62
with trisomy plus
a ba
l
a
n
ced
tr
a
nslo
ca
tion
.
Ga
r
c
i
a
-
E
ngui
da
nos
(
2002
)
foun
d
th
a
t th
e
risk of spont
a
n
e
ous
ab
ortion in
c
r
ea
s
ed b
y
in
c
r
ea
sing m
a
t
e
rn
a
l
a
g
e
,
e
sp
ec
i
a
lly
a
ft
e
r th
e a
g
e
of
35
y
ea
rs or mor
e
.
A
n
de
rs
e
n
(
2000
)
foun
d
th
e
risk of spont
a
n
e
ous
ab
ortion
b
y
11
.
1
%
-
15
.
0
%
a
t un
de
r
35
y
ea
rs ol
d
,
whi
c
h in
c
r
ea
s
ed
to
24
.
6
%
a
t th
e a
g
e
of
35
y
ea
rs
.
He
fn
e
r
(
2004
)
a
lso foun
d
simil
a
r
r
e
sults
,
with th
e
risk of spont
a
n
e
ous
ab
ortion
b
y
10
-
14
%
a
t th
e a
g
e
of
20
-
34
y
ea
rs
,
a
n in
c
r
ea
s
e
to
24
%
a
ft
e
r
a
g
e
35
y
ea
rs
,
a
n
d
50
%
a
ft
e
r
40
y
ea
rs of
a
g
e
.
2
.
2
.
C
hromosom
e
2
.
2
.
1
C
hromosom
e S
tru
c
tur
e
H
um
a
ns
a
r
e e
uk
a
ryoti
c
org
a
nisms
,
whos
e ce
lls h
a
v
e a
tru
e c
or
e
th
a
t is limit
ed b
y
c
or
e
m
e
m
b
r
a
n
e
s
,
a
n
d b
r
eed
through mitosis
.
I
nst
ead
,
bac
t
e
ri
a a
r
e
prok
a
ryoti
c
org
a
nisms th
a
t
d
o not h
a
v
e a
tru
e c
or
e a
n
d
r
e
pro
d
u
ce
through
ce
ll
d
ivision
.
E
x
ce
pt
DNA
in th
e
mito
c
hon
d
ri
a
,
a
ll of our
DNA
is stor
ed
in th
e ce
ll nu
c
l
e
us surroun
ded b
y
c
or
e
m
e
m
b
r
a
n
e
s
.
Beca
us
e
ovum is ri
c
h in mito
c
hon
d
ri
a
,
d
is
ea
s
e
s
ca
us
ed b
y
mito
c
hon
d
ri
a
l g
e
n
e
s
(
for
e
x
a
mpl
e
,
Lebe
r
'
s
O
pti
c Ne
urop
a
thy
)
is inh
e
rit
ed
through
moth
e
rs
,
beca
us
e
mito
c
hon
d
ri
a
in sp
e
rm is r
e
mov
ed d
uring f
e
rtiliz
a
tion
.
C
hromosom
e
s
a
r
e a c
oll
ec
tion of g
e
n
e
ti
c
m
a
t
e
ri
a
l
c
onsisting of
DNA
mol
ec
ul
e
s
(
whi
c
h
c
ont
a
in m
a
ny g
e
n
e
s
)
whi
c
h
a
r
e a
tt
ac
h
ed
to
a
l
a
rg
e
num
be
r of prot
e
ins th
a
t
m
a
int
a
in th
e
stru
c
tur
e
of th
e c
hromosom
e a
n
d
pl
a
y
a
rol
e
in g
e
n
e e
xpr
e
ssion
.
H
um
a
n som
a
ti
c ce
lls h
a
v
e c
hromosom
e
s with
22
p
a
irs of
a
utosom
e
s
a
n
d
1
p
a
ir of
s
e
x
c
hromosom
e
s
.
A
ll som
a
ti
c ce
lls
a
r
e d
iploi
d
,
with
23
p
a
irs of
c
hromosom
e
s
.
O
nly
h
a
ploi
d
g
a
m
e
t
e
s
,
with
22
c
hromosom
e a
utosom
e
s
a
n
d
1
s
e
x
c
hromosom
e
.
T
h
e
siz
e
of th
e c
hromosom
e
v
a
ri
e
s from
50
million to
250
million
a
lk
a
lin
e
p
a
irs
.
C
hromosom
e
1
h
a
s th
e
l
a
rg
e
st num
be
r of g
e
n
e
s
(
2968
g
e
n
e
s
)
a
n
d
th
e Y
c
hromosom
e
h
a
s th
e
l
ea
st num
be
r of g
e
n
e
s
(
231
g
e
n
e
s
).
A
ll
c
hromosom
e
s h
a
v
e a
c
onn
ec
ting s
ec
tion
ca
ll
ed
th
e ce
ntrom
e
r
,
whi
c
h
d
ivi
de
s th
e c
hromosom
e
into two
a
rms
:
short sl
ee
v
e
s
(
P
)
a
n
d
long sl
ee
v
e
s
(
q
).
T
wo m
e
m
be
rs of
eac
h p
a
ir of
a
utosom
e
s
a
r
e
homologi
e
s
,
eac
h of whi
c
h
c
om
e
s from f
a
th
e
r
a
n
d
moth
e
r
.
A
g
e
n
e
is
a DNA
unit in
c
hromosom
e
s th
a
t
ca
n
be ac
tiv
a
t
ed
to tr
a
nsl
a
t
e
sp
ec
ifi
c
RNA
.
T
h
e
lo
ca
tion of th
e
g
e
n
e
in th
e c
hromosom
e
is
ca
ll
ed
th
e
lo
c
us
.
Beca
us
e
th
e
r
e
a
r
e
22
p
a
irs of
a
utosom
e
s
,
most g
e
n
e
s
a
pp
ea
r in
a
p
a
rtn
e
r
.
T
h
e c
oupl
e
is
ca
ll
ed
homozygot if th
e
s
a
m
e a
n
d
h
e
t
e
rozygous if it
'
s
d
iff
e
r
e
nt
.
2
.
2
.
1
.
1
C
hromosom
e
s in th
e
m
e
t
a
ph
a
s
e
ph
a
s
e
C
hromosom
e
s
a
t th
e
m
e
t
a
ph
a
s
e
st
a
g
e
v
a
ry in l
e
ngth
,
th
e
lo
ca
tion of th
e
ce
ntrom
e
r
e
,
a
n
d
th
e
siz
e a
n
d
p
a
tt
e
rn of
b
right
a
n
d da
rk ri
bb
ons
(
ri
bb
on p
a
tt
e
rn
).
Eac
h
c
hromosom
e a
n
d
p
a
rts
ca
n
be
r
ec
ogniz
ed
from th
e
p
a
tt
e
rn of th
e
ir
d
iplom
a
.
I
n
st
a
n
da
r
d
m
e
t
a
ph
a
s
e
pr
e
p
a
r
a
tions
,
th
e
r
e a
r
e
300
-
550
d
iff
e
r
e
nt ri
bb
ons th
a
t
ca
n
be
i
de
ntifi
ed
.
I
n th
e P
rom
e
t
a
f
a
s
e
ph
a
s
e
,
c
hromosom
e
s
a
r
e
long
e
r th
a
n in th
e
m
e
t
a
ph
a
s
e
ph
a
s
e a
n
d
show mor
e
ri
bb
ons
.
T
h
e
r
e
for
e
,
for
ce
rt
a
in purpos
e
s
,
c
hromosom
e
s
a
r
e a
lso stu
d
i
ed
in th
e P
rom
e
t
a
f
a
s
e
ph
a
s
e
.
2
.
2
.
1
.
2
Me
t
a
ph
a
s
e C
hromosom
e T
yp
e
Eac
h
c
hromosom
e
is
ca
t
e
goriz
ed a
s su
b
m
e
t
a
s
ce
ntri
c
,
m
e
t
a
s
ce
ntri
c
,
or
ac
ro
ce
ntri
c
ba
s
ed
on th
e
position of th
e ce
ntrom
a
ir
e
.
T
h
e ce
ntrom
e
r
e
fun
c
tions
a
s
a
c
on
c
urr
e
n
c
y point
,
th
e
pl
ace
is
a
tt
ac
h
ed
to
a b
o
bb
in
d
uring mitosis
.
I
n
su
b
m
e
t
a
s
ce
ntri
c c
hromosom
e
s
,
th
e ce
ntrom
e
r
d
ivi
de
s
c
hromosom
e
s into short
sl
ee
v
e
s
(
a
rm p
)
a
n
d
long
a
rms
(
a
rm
Q
).
I
n m
e
t
a
s
ce
ntri
c c
hromosom
e
s
,
short sl
ee
v
e
s
a
r
e a
lmost th
e
s
a
m
e a
s long sl
ee
v
e
s
.
W
h
e
r
ea
s in th
e ac
ro
ce
ntri
c c
hromosom
e
,
th
e
short
a
rm is in th
e
form of
a
n
add
ition
a
l stru
c
tur
e ca
ll
ed
s
a
t
e
llit
e
.
2
.
2
.
1
.
3
Ka
riotyp
e
Ka
riotip
e
is
a c
ompl
e
t
e c
ir
c
uit of
c
hromosom
e
s
c
ont
a
in
ed
in
ce
lls from
a
n in
d
ivi
d
u
a
l
or sp
ec
i
e
s
.
Ka
ryotyp
e
is
a
mi
c
ros
c
opi
c
vi
e
w of th
e c
hromosom
e
in th
e
m
e
t
a
ph
a
s
e
ph
a
s
e
,
vi
e
w
ed ba
s
ed
on its morphology
.
A
ft
e
r th
e
pro
ce
ss of prot
e
oliz
a
tion
a
n
d
c
oloring with
G
i
e
ms
a
,
it looks
c
h
a
r
ac
t
e
risti
c
of
a
ll
c
hromosom
e
s
.
Ca
rogr
a
m shows
homologous
c
hromosom
e
s
,
n
a
m
e
ly on
e c
hromosom
e
from th
e
moth
e
r
a
n
d
on
e
of
th
e
f
a
th
e
r
,
whi
c
h is sort
ed acc
or
d
ing to th
e
r
e
l
a
tiv
e
l
e
ngth
a
n
d
position of th
e
ce
ntrom
e
r
.
C
hromosom
e
s
a
r
e a
rr
a
ng
ed a
n
d
visit
ed acc
or
d
ing to th
e c
onv
e
ntion
.
S
t
a
rting with th
e
num
be
r of
c
hromosom
e
s
,
follow
ed b
y th
e a
rr
a
ng
e
m
e
nt of s
e
x
c
hromosom
e
s
.
A
ll
ce
ll
c
h
a
ng
e
s
a
r
e e
xpl
a
in
ed
through mos
a
i
c ab
norm
a
liti
e
s
.
E
x
ce
ss
or lost
c
hromosom
e
s
a
r
e
in
d
i
ca
t
ed b
y th
e
+
or
-,
a
s w
e
ll
a
s th
e
typ
e
of
ab
norm
a
lity
if th
e
r
e
is
a
ring
c
hromosom
e
.
T
h
e
stru
c
tur
a
l stru
c
tur
e
is
e
xpl
a
in
ed b
y
a
rm
P
or
Q
a
n
d
th
e
ri
bb
on position
.
2
.
2
.
1
.
4
C
hromosom
e A
rr
a
ng
e
m
e
nt
C
hromosom
e
s
a
r
e
only s
ee
n
a
s s
e
p
a
r
a
t
e
stru
c
tur
e
s
d
uring mitosis
.
I
n int
e
rf
a
s
e
s
,
c
hromosom
e
s
a
pp
ea
r
a
s irr
e
gul
a
r m
a
ss
e
s
a
n
d a
r
e ca
ll
ed c
hrom
a
tin
.
C
hrom
a
tins
h
a
v
e
v
a
ri
ed de
nsiti
e
s
,
n
a
m
e
ly h
e
t
e
ro
c
hrom
a
tin
(
with high
de
nsity
)
a
n
d e
ukrom
a
tin
(
with low
de
nsity
).
E
ukrom
a
tin
c
ont
a
ins
ac
tiv
e
g
e
n
e
s
,
whil
e
h
e
t
e
ro
c
hrom
a
tin
c
ont
a
ins
a
n in
ac
tiv
e
g
e
n
e
.
a
. **
C
hromosom
e
stru
c
tur
e
l
e
v
e
l
**
F
rom th
e c
hromosom
e
to th
e DNA c
h
a
in
,
th
e
r
e
is
a d
iff
e
r
e
n
ce a
t th
e
l
e
v
e
l of th
e
stru
c
tur
e
.
T
h
e
tot
a
l l
e
ngth of
Ha
ploi
d DNA
in hum
a
n
ce
lls is splitting
ab
out
1
m
e
t
e
r
.
D
uring mitosis
,
th
e e
ntir
e DNA
w
a
s wr
a
pp
ed
in
23
c
hromosom
e
s
,
with th
e
l
e
ngth of
eac
h
c
hromosom
e a
roun
d
3
-
7 μ
m
.
I
f on
e
p
a
rt of th
e c
hromosom
e a
rm is roughly
10
%
of th
e
l
e
ngth of th
e c
hromosom
e
is
e
nl
a
rg
ed
10
tim
e
s
,
it will
a
pp
ea
r
a
roun
d
40
g
e
n
e
s
,
de
p
e
n
d
ing on th
e
o
b
s
e
rv
ed c
hromosom
e
s
e
gm
e
nt
.
I
f
10
%
of th
e
oth
e
r p
a
rts
a
r
e e
nl
a
rg
ed
10
tim
e
s
,
it will
a
pp
ea
r
a
n
a
v
e
r
a
g
e
of
3
-
4
g
e
n
e
s
.
Ma
gnifi
ca
tion
10
tim
e
s mor
e
will
d
ispl
a
y on
e
g
e
n
e
with
a
n
e
xon
/
intron stru
c
tur
e
.
F
in
a
lly
,
it is
a
s
e
qu
e
n
ce
of nu
c
l
e
oti
de
s from g
e
n
e
s
a
n
d DNA a
roun
d
it
.
b
r
ea
kf
a
st
. **
DNA a
n
d
nu
c
l
e
osom
e
**
W
h
e
n int
e
rf
a
s
e
s
,
DNA a
long with r
e
l
e
v
a
nt prot
e
ins
(
histon
e
)
a
r
e
v
e
ry tight in
c
hrom
a
tin
.
T
h
e c
hrom
a
tin
ba
si
c
stru
c
tur
e
unit is nu
c
l
e
osom
e
,
whi
c
h
c
onsists of
8
c
or
e
histon mol
ec
ul
e
s
,
n
a
m
e
ly two
c
opi
e
s of
H
2
A
,
H
2
B
,
H
3
,
a
n
d H
4
,
whi
c
h
a
r
e
wr
a
pp
ed b
y
140
-
150
DNA ba
s
e
p
a
irs
.
Add
ition
a
l p
a
irs of
48
ba
s
e
s s
e
gm
e
nts form
r
e
l
a
tionships with n
e
igh
b
oring nu
c
l
e
osoms
a
n
d
oth
e
r typ
e
s of histon
e
s
(
H
1
or
H
5
)
whi
c
h
a
r
e b
oun
d
to this
DNA
.
T
h
e
nu
c
l
e
osom h
a
s
a d
i
a
m
e
t
e
r of
11
N
m
a
n
d a
h
e
ight
of
6
nm
,
c
ir
c
ling th
e c
or
e
.
DNA e
nt
e
rs
a
n
d e
xits th
e
nu
c
l
e
osom
a
t
ce
rt
a
in points
.
F
or
th
e
pro
ce
ss of tr
a
ns
c
ription
a
n
d
r
e
p
a
iring
DNA
,
th
e c
los
e
r
e
l
a
tionship
be
tw
ee
n
DNA
a
n
d
histony will
be
r
e
l
a
x
ed
.
T
his
c
hromosom
e
stru
c
tur
e
is known
a
s
"
str
a
n
d
s of
bead
s
."
C
.. **
c
hrom
a
tin stru
c
tur
e
**
C
hrom
a
tins
ca
n
be
in
c
on
de
ns
ed
forms with soli
d
,
l
e
ss
c
on
de
ns
ed
,
or not
c
on
de
ns
ed
.
I
n
ce
ll
c
or
e
stru
c
tur
e
s
,
most
c
hrom
a
tin
a
pp
ea
rs
a
s
a
fi
be
r with
a
d
i
a
m
e
t
e
r of
30
nm
.
d
. **
c
hrom
a
tin s
e
gm
e
nt
**
T
h
e c
hrom
a
tin stru
c
tur
e
is
b
uilt from thr
ee c
hrom
a
tin l
e
v
e
ls
,
forming
a
30
-
N
m fi
be
r
a
rr
a
ng
e
m
e
nt th
a
t is int
e
gr
a
t
ed
in on
e c
lot
.
He
y
. **
DNA
in
c
hromosom
e
s
**
Be
for
e
mitosis
,
th
e
int
e
rf
ace c
hromosom
e c
on
de
ns
ed
into mitosis
c
hromosom
e
s
.
C
h
a
ng
e
s from th
e
int
e
rf
ace c
hromosom
e
to mitoti
c c
hromosom
e
s r
e
quir
e
sp
ec
i
a
l
prot
e
in
ca
ll
ed c
on
de
nsins
;
T
h
e e
n
e
rgy of th
e ATP
hy
d
rolysis is n
eeded
to
c
h
a
ng
e
th
e c
hromosom
e
int
e
rf
ace
into mitoti
c c
hromosom
e
s
.
DNA c
hromosom
e
s
a
r
e
fol
ded a
n
d c
ompil
ed e
ffi
c
i
e
ntly
.
T
h
e
six l
e
v
e
ls of
DNA
stru
c
tur
e
s
a
r
e a
rr
a
ng
ed a
n
d
p
ac
k
a
g
ed
in m
e
t
a
ph
a
s
e c
hromosom
e
s
.
**
2
.
2
.
2
mitosis
**
A
ll
e
uk
a
riot
,
from mushrooms to hum
a
ns
,
e
xp
e
ri
e
n
ce
s
ce
ll
d
ivision in
a
simil
a
r w
a
y
.
T
h
e
pro
ce
ss of
c
l
ea
ving
ce
ll
c
or
e
in som
a
ti
c ce
lls is
ca
ll
ed
mitosis
.
I
n mitosis
,
eac
h
c
hromosom
e
is
d
ivi
ded
into two
.
F
or norm
a
l growth
a
n
d de
v
e
lopm
e
nt
,
a
ll g
e
nom
e
inform
a
tion must
be
r
e
pro
d
u
ced
in
eac
h
ce
ll
.
M
itosis
c
onsists of th
e
following ph
a
s
e
s
:
- **
I
nt
e
rf
a
s
e
**:
ce
lls un
de
rgo norm
a
l
ac
tiviti
e
s
e
x
ce
pt
ac
tiv
e d
ivision
.
I
n this ph
a
s
e
,
th
e
in
ac
tiv
e X c
hromosom
e
(
Ba
rr or
Se
x
c
hrom
a
tin
b
o
d
y
)
ca
n
be
s
ee
n in wom
e
n
'
s
ce
lls
.
- **
P
rof
a
s
e
**:
C
l
ea
ns
e
s
be
gin with
c
hromosom
e c
on
de
ns
a
tion
,
a
n
d
two
c
hrom
a
ti
d
s
a
r
e
visi
b
l
e
;
Eac
h
c
hromosom
e d
ou
b
l
e
s his
d
n
a
ny
a
.
N
u
c
l
e
us m
e
m
b
r
a
n
e
is
lost
.
Se
ntriol
,
org
a
n
e
ll
e
outsi
de
th
e
nu
c
l
e
us
,
forms
a b
o
bb
in for
ce
ll
d
ivision
.
Se
ntriol
d
upli
ca
t
e
s its
e
lf
a
n
d
two
ce
ntriol mov
e
s to th
e
opposit
e ce
ll pol
e
.
- **
Me
t
a
ph
a
s
e
**:
C
hromosom
e
s mov
e
to th
e
mi
dd
l
e
of th
e ce
ll
a
n
d
form
a
lin
e
in
th
e e
qu
a
tori
a
l fi
e
l
d
.
C
hromosom
e
s
a
r
e
now m
a
ximum
c
on
de
ns
ed
.
T
h
e
mi
c
rotu
b
ul
b
o
bb
in from prot
e
ins th
a
t
c
om
e
s from th
e ce
ntriol spr
ead a
n
d a
tt
ac
h
ed
to th
e
ce
ntrom
a
ir
e
.
- **
A
n
a
f
a
s
e
**:
d
ivision o
cc
urs in th
e L
ongitu
d
in
a
l fi
e
l
d
of th
e ce
ntrom
a
ir
e
.
T
h
e
two
n
e
w
c
hrom
a
ti
d
s mov
ed
to th
e
opposit
e
si
de
of th
e ce
ll
,
with
d
r
a
wn
b
y
c
ontr
ac
tions
of th
e b
o
bb
in
.
- **
Te
lof
a
s
e
**:
S
itopl
a
sm
a d
ivision st
a
rts in th
e e
qu
a
tori
a
l fi
e
l
d
,
e
n
d
ing with th
e
form
a
tion of two
c
ompl
e
t
e ce
ll m
e
m
b
r
a
n
e
s
.
T
h
e
two
c
hromosom
e
groups
a
r
e
surroun
ded b
y nu
c
l
e
us m
e
m
b
r
a
n
e
s
,
pro
d
u
c
ing two n
e
w nu
c
l
e
us
.
Eac
h
DNA c
h
a
in
s
e
rv
e
s
a
s
a
mo
de
l
,
a
n
d
th
e
num
be
r of
DNA
in th
e ce
ll
d
ou
b
l
ed
.
E
v
e
ry
c
hil
d ce
ll
r
ece
iv
e
s h
a
lf of th
e
multipl
e c
hromosom
e
m
a
t
e
ri
a
l
,
k
ee
ping th
e
num
be
r of
c
hromosom
e
s r
e
m
a
in th
e
s
a
m
e a
s th
e
st
e
m
ce
ll
.
**
2
.
2
.
3
m
e
iosis
**
Me
iosis is
ce
ll
d
ivision th
a
t pro
d
u
ce
s g
a
m
e
t
e
s with th
e
num
be
r of h
a
ploi
d
c
hromosom
e
s
.
T
h
e
purpos
e
of m
e
iosis is
a
r
ed
u
c
tion in th
e
num
be
r of
c
hromosom
e
s
a
n
d
r
ec
om
b
in
a
tion of g
e
n
e
ti
c
inform
a
tion
.
I
n
Me
iosis
I
,
th
e
homolog
c
hromosom
e
p
a
ir mov
ed a
w
a
y
.
Me
iosis
II
is simil
a
r to mitosis th
a
t
d
ivi
de
s
c
hromosom
e
s into two
,
forming two n
e
w
ce
lls
.
**
first m
e
iosis
d
ivision
(
m
e
iosis i
) **
T
h
e Me
iiosis
I
pro
ce
ss st
a
rts with
a c
on
de
ns
ed
ph
a
s
e
of prof
a
s
e
.
- **
P
rof
a
s
e
**
- **
Le
pot
e
n
e
**:
C
hromosom
e c
on
de
ns
a
tion
.
- **
Z
igot
e
n
e
**:
homologous
c
hromosom
e
s in p
a
irs
(
syn
a
ps
e
s
).
- **
Pa
kit
e
n
e
**:
E
v
e
ry
c
hromosom
e
p
a
ir thi
c
k
e
n
ed
4
c
hrom
a
ti
d c
h
a
ins
.
I
n this ph
a
s
e
c
ross ov
e
r
(
c
ross ov
e
r
)
or r
ec
om
b
in
a
tion
be
tw
ee
n homolog s
e
gm
e
nts of two
c
hrom
a
ti
d c
h
a
ins
.
K
i
a
sm
a
t
a
is th
e
pl
ace
wh
e
r
e
'
C
ross
O
v
e
r
'
h
a
pp
e
ns
.
T
h
e
mov
e
m
e
nt of this
DNA b
lo
c
k
c
r
ea
t
e
s g
e
n
e
ti
c d
iv
e
rsity
.
- **
D
iplot
e
n
e
**:
L
ongitu
d
in
a
l s
e
p
a
r
a
tion of
eac
h
c
hromosom
e
.
**
m
e
t
a
ph
a
s
e
,
a
n
a
f
a
s
e
,
a
n
d
t
e
lof
a
s
e
m
e
iosis i
**
T
h
e
nu
c
l
e
us m
e
m
b
r
a
n
e d
is
a
pp
ea
rs
a
n
d
th
e c
hromosom
e
mov
e
s into th
e
mi
dd
l
e
of
th
e ce
ll
.
O
n
e
m
e
m
be
r of
eac
h
c
hromosom
e
p
a
ir mov
e
s to
a d
iff
e
r
e
nt
ce
ll poly
,
a
n
d
th
e ce
ll
d
ivi
de
s
.
Me
iosis
I
is oft
e
n
ca
ll
ed
r
ed
u
c
tion
d
ivision
beca
us
e e
v
e
ry n
e
w
pro
d
u
c
t h
a
s
a
num
be
r of h
a
ploi
d c
hromosom
e
s
.
De
w
e
li
a
n inh
e
rit
a
n
ce
o
cc
urs in
m
e
iosis
I
.
C
ross
-
e
x
c
h
a
ng
e be
for
e
m
e
t
a
ph
a
s
e
pro
d
u
ce
s
a c
om
b
in
a
tion of n
e
w
g
e
n
e
ti
c
m
a
t
e
ri
a
l th
a
t
ca
n
be
us
e
ful or
de
trim
e
nt
a
l
.
**
s
ec
on
d
m
e
iosis
d
ivision
(
m
e
iosis
II
) **
De
strortion
Me
iosis
II
follow
ed
m
e
iosis without r
e
pli
ca
tion of
DNA
.
O
n oo
c
yt
e
s
,
m
e
iosis
II
o
cc
urs
a
ft
e
r f
e
rtiliz
a
tion
.
T
h
e
fin
a
l r
e
sult is four h
a
ploi
d ce
lls with
c
hromosom
e
22
+
1
x or
22
+
1
y
.
**
2
.
2
.
4
c
hromosom
e
/
g
e
n
e
ti
c ab
norm
a
liti
e
s
**
T
h
e
m
a
in
ca
us
e
of spont
a
n
e
ous
ab
ortion is
c
hromosom
e ab
norm
a
liti
e
s
,
whi
c
h o
cc
ur
a
lmost
50
%
of
ca
s
e
s
.
C
oroni
c V
illi
e
x
a
min
a
tion
c
onfirm
ed
with ultr
a
soun
d
shows
th
e
fr
e
qu
e
n
c
y of
c
hromosom
a
l
ab
norm
a
liti
e
s in pr
e
gn
a
n
c
y th
a
t
d
o
e
s not
de
v
e
lop
r
eac
h
75
-
90
%
.
N
um
e
ri
ca
l
ab
norm
a
liti
e
s
a
r
e
usu
a
lly
ca
us
ed b
y non
-
d
isjun
c
tions
,
n
a
m
e
ly th
e
f
a
ilur
e
of
c
hromosom
e
s
e
p
a
r
a
tion in th
e
ph
a
s
e
of
a
n
a
f
a
s
e d
uring mitosis
or m
e
iosis
.
A
n
e
uploi
d
i is
a de
vi
a
tion of th
e
num
be
r of
c
hromosom
e
s whi
c
h r
e
sults in loss or
add
ing on
e
or mor
e c
hromosom
e
s from th
e
num
be
r of
d
iploi
d
s
,
su
c
h
a
s
a
monosomy
(
45
,
x turn
e
r syn
d
rom
e
)
or trisomy
(
trisomy
13
,
p
a
t
a
u syn
d
rom
e
,
T
risomy
18
:
Ed
w
a
r
d S
yn
d
rom
e
,
T
risomy
21
D
own
S
yn
d
rom
e
,
47
,
XXY S
yn
d
rom
e K
linf
e
lt
e
r
).
M
os
a
i
c
s show on
e
or mor
e ce
ll
de
riv
a
tiv
e
s with k
a
ryotyp
e c
h
a
ng
e
s
,
usu
a
lly
d
u
e
to
non
-
d
isjun
c
tion
a
t th
e be
ginning of mitosis
(
two p
a
irs of
c
hromosom
e
s f
a
il
ed
to
s
e
p
a
r
a
t
e
).
P
olyploi
d
i
,
th
e
num
be
r of
c
hromosom
e
s th
a
t
d
ou
b
l
ed
from th
e
num
be
r of h
a
ploi
d
s
,
is
a
signifi
ca
nt
ca
us
e
of spont
a
n
e
ous
ab
ortion
.
T
h
e
fr
e
qu
e
n
c
y of non
d
i
S
jun
c
tion in
hum
a
ns is influ
e
n
ced b
y m
a
t
e
rn
a
l
a
g
e
wh
e
n
c
on
ce
ption
.
N
on
d
isjun
c
tion
ca
n o
cc
ur
d
uring m
e
iosis
I
or m
e
iosis
II
.
I
n
Me
iosis
I
,
on
e c
hil
d ce
ll r
ece
iv
e
s two
c
hromosom
e
s
(
norm
a
lly on
e c
hromosom
e
)
whil
e
oth
e
r
c
hil
d
r
e
n
ce
lls
d
o not
acce
pt
c
hromosom
e
s
,
g
e
n
e
r
a
t
e
g
a
m
e
ts with two
c
hromosom
e
s
(
d
isomi
)
or without
c
hromosom
e
s
(
nullisomy
).
D
uring
Ma
yiosis
II
,
on
e c
hil
d ce
ll will r
ece
iv
e
two
c
hromosom
e
s
(
bec
om
e
d
is
c
o
),
whil
e
oth
e
r
c
hil
d
r
e
n
ce
lls
d
o not
acce
pt
c
hromosom
e
s
(
nullisomy
).
A
ft
e
r
f
e
rtiliz
a
tion
,
th
e
g
a
m
e
t
d
ismomy pro
d
u
ce
s zygot trisomy
,
a
n
d
nullisomy g
a
m
e
t
pro
d
u
ce
s zygot monosomy
.
A
n
e
uploi
d
i
c
ov
e
rs s
e
v
e
r
a
l typ
e
s
,
su
c
h
a
s
: (
i
)
trisomy
(
thr
ee c
hromosom
e
s in on
e
p
a
ir
), (
ii
)
monosomy
(
on
e c
hromosom
e
in on
e
p
a
rtn
e
r
),
a
n
d
(
iii
)
triploi
d
i
a
n
d
t
e
tr
a
ploi
d
i
(
num
be
r of
c
hromosom
e
s multipli
ed T
hr
ee
or four
).
T
riploi
d
i
ca
n
be
ca
us
ed b
y non
d
isjun
c
tion
d
uring m
e
iosis
,
or
b
y
d
isp
e
rmi
a
,
wh
e
r
e
two sp
e
rm
f
e
rtiliz
e
s on
e
ovum
.
O
vum or sp
e
rm
ca
n
a
lso
c
ont
a
in
c
hromosom
e
s th
a
t h
a
v
e
not
bee
n r
ed
u
ced d
u
e
to r
e
stitution in m
e
iosis
I
or
II
,
or th
e
s
ec
on
d
pol
a
r
b
o
d
y
ca
n join
th
e
h
a
ploi
d e
gg nu
c
l
e
us
.
D
isfim
a
r
e
sults in two of th
e
thr
ee
s
e
ts of
c
hromosom
e
s
from
Pa
t
e
rn
a
l
,
pro
d
u
ce
69
,
xyy
,
69
,
xxy
,
or
69
,
xxx
.
D
isfim
a
is th
e ca
us
e
of triploi
d
i
in
66
%
of
ca
s
e
s
,
whil
e
th
e
f
e
rtiliz
a
tion of h
a
ploi
d e
ggs with
a d
iploi
d
sp
e
rm o
cc
urs
in
24
%
of
ca
s
e
s
(
Me
iosis
I
f
a
ilur
e
)
a
n
d d
iploi
d e
ggs foun
d
in
10
%
.
T
riploi
d
i is on
e
of
th
e
m
a
in
ca
us
e
s of spont
a
n
e
ous
ab
ortion in m
e
n
,
ca
using
17
%
of spont
a
n
e
ous
ab
ortion
,
whil
e
t
e
tr
a
ploi
d
i is l
e
ss r
a
r
e
.
I
n hum
a
ns
,
th
e
r
e a
r
e
only thr
ee
trisomy
a
utosom
e
s foun
d
in liv
e b
irths
:
T
risomy
13
(
1
in
12
,
000
),
T
risomy
18
(
1
in
6
,
000
),
a
n
d
T
risomy
21
(
1
in
650
).
T
h
e
risk of trisomy of
a
utosom
e
s in
c
r
ea
s
ed
in moth
e
rs
a
g
ed
ov
e
r
35
y
ea
rs
,
a
n
d beca
m
e
t
e
nfol
d
for moth
e
rs ov
e
r
40
y
ea
rs
.
Add
ition
a
l
X
or
Y
c
hromosom
e
s o
cc
ur in
1
of
800
bab
i
e
s
b
orn
a
n
d ca
n
ca
us
e
sp
eec
h
d
isor
de
rs
,
limit
ed
l
ea
rning skills
,
a
n
d a
ttitu
de
pro
b
l
e
ms
.
P
l
ac
hot
e
t
a
l r
e
port
ed
th
a
t
c
hromosom
e ab
norm
a
liti
e
s w
e
r
e
mor
e
oft
e
n foun
d
in
e
m
b
ryoni
c ab
norm
a
liti
e
s
,
with
78
%
ab
norm
a
l
e
m
b
ryos
c
omp
a
r
ed
to
12
.
5
%
of
norm
a
l
e
m
b
ryos
.
M
ost of th
e
spont
a
n
e
ous
ab
ortion is
ca
us
ed b
y th
e
k
a
ryotypi
ca
l
e
m
b
ryo
d
isor
de
r
,
with
a
roun
d
50
%
of mis
ca
rri
a
g
e
s in th
e
first trim
e
st
e
r r
e
l
a
t
ed
to
c
ytog
e
n
e
ti
c ab
norm
a
liti
e
s
.
E
m
b
ryo
c
ytog
e
n
e
ti
c ab
norm
a
liti
e
s
a
r
e
usu
a
lly in th
e
form
of
a
n
e
uploi
d
y
d
u
e
to non
d
isjun
c
tion m
e
iosis or polyploi
d
i
.
W
om
e
n
a
g
ed
41
y
ea
rs
with
c
hromosom
e ab
norm
a
liti
e
s
a
n
d
m
a
lform
a
tions v
e
ry lik
e
ly to
e
xp
e
ri
e
n
ce
mis
ca
rri
a
g
e
s
.
S
itog
e
n
e
ti
c a
n
a
lysis is import
a
nt for knowing th
e ca
us
e
s of
mis
ca
rri
a
g
e
,
a
n
d c
ultur
e a
n
d
tropho
b
l
a
st
a
n
a
lysis
a
r
e
r
a
r
e
ly
d
on
e e
x
ce
pt in
r
ec
urr
e
nt mis
ca
rri
a
g
e
s
.
Ka
riotip
c
on
ce
ption pro
d
u
c
ts provi
de
us
e
ful inform
a
tion for
futur
e
pr
e
gn
a
n
c
y
c
ouns
e
ling
a
n
d
h
a
n
d
ling
.
S
itog
e
n
e
ti
c ab
norm
a
liti
e
s
ca
n
be
in th
e
form of num
e
ri
ca
l
ab
norm
a
liti
e
s
,
c
hromosom
e
stru
c
tur
e
s
,
or mos
a
i
c
s
.
N
um
e
ri
ca
l
ab
norm
a
liti
e
s in
c
lu
de a
n
e
uploi
d
i
a
n
d
polyploi
d
i
;
T
risomy is mor
e c
ommon th
a
n polli
d
i
(
21
%
)
a
n
d
monosomy x
(
13
%
).
D
i
e
go
A
lv
a
r
e
z
e
t
a
l
(
2005
)
r
ec
or
ded
s
e
v
e
n
d
ou
b
l
e
trisomy
ca
s
e
s from
321
ca
s
e
s of
spont
a
n
e
ous
ab
ortion
(
21
.
8
%
).
T
h
e d
ou
b
l
e
trisomy fr
e
qu
e
n
c
y w
a
s r
e
port
ed be
tw
ee
n
0
.
21
%
to
2
.
8
%
,
with
a
pr
e
gn
a
n
c
y
a
g
e
of
a d
ou
b
l
e
trisomy
ca
s
e
of
9
.
4
±
2
.
1
w
ee
ks
.
A
n
e
uploi
d
i
A
utosom
a
l o
cc
urs
d
u
e
to
e
rrors in m
e
iosis
I
,
whi
c
h
a
r
e
oft
e
n r
e
l
a
t
ed
to
ol
d
wom
e
n
a
n
d a dec
r
ea
s
e
in r
ec
om
b
in
a
tion of m
e
ioti
c
.
C
hromosom
e e
rrors oft
e
n
o
cc
ur in th
e
f
e
tus who
e
xp
e
ri
e
n
ced
spont
a
n
e
ous
ab
ortion
.
Jac
o
b
s
&
Ha
ssol
d
(
1980
)
r
e
port
ed
th
a
t
ab
out
a
qu
a
rt
e
r of
c
hromosom
a
l
ab
norm
a
liti
e
s w
e
r
e ca
us
ed b
y
moth
e
rs
a
n
d
5
%
g
a
m
e
thog
e
n
e
sis
e
rrors
b
y f
a
th
e
r
'
s mist
a
k
e
s
.
R
o
b
inson
e
t
a
l
(
1996
)
foun
d
th
a
t on
21
of th
e
23
trisomy
13
ca
s
e
s
,
add
ition
a
l
c
hromosom
e
s
ca
m
e
from th
e
moth
e
r
.
A
n
e
uploi
d
i
Fe
tus is th
e
m
a
in
ca
us
e
of mis
ca
rri
a
g
e be
for
e
10
w
ee
ks
,
with
a
roun
d
50
-
60
%
mis
ca
rri
a
g
e
r
e
l
a
t
ed
to
c
ytog
e
n
e
ti
c ab
norm
a
liti
e
s
,
e
sp
ec
i
a
lly trisomy
,
follow
ed b
y polyploi
d
y
a
n
d
monosomy
X
.
A
n
e
uploi
d
i is usu
a
lly
ca
us
ed b
y
e
rrors on
T
h
e
first m
e
iosis oo
c
yt
e
,
whi
c
h st
a
rts in th
e
pr
e
n
a
t
a
l p
e
rio
d a
n
d c
ontinu
e
s to
ovul
a
tion
.
O
l
de
r m
a
t
e
rn
a
l
a
g
e
is
a
sso
c
i
a
t
ed
with
a dec
r
ea
s
e
in oo
c
yt
e
m
a
turity
a
n
d
limit
ed
oo
c
yt
c
ount
,
whi
c
h
ca
n
ca
us
e a
n
e
uploi
d
i
.
A
n
e
uploi
d
i is th
e
m
a
in
ca
us
e
of spont
a
n
e
ous
ab
ortion
,
a
n
d
in
c
lu
de
s trisomy
21
,
18
,
22
,
a
n
d
s
e
x
c
hromosom
e
s
.
T
risomy is g
e
n
e
r
a
lly
ca
us
ed b
y
e
rrors in m
e
iosis th
a
n
moth
e
rs
,
whil
e
monosomy x oft
e
n involv
e
s losing
c
hromosom
e
x from f
a
th
e
r
.
Ab
out
15
%
of pr
e
gn
a
n
c
i
e
s
e
n
ded
with spont
a
n
e
ous
ab
ortion
d
u
e
to
c
hromosom
e
c
om
b
in
a
tion
e
rrors in m
e
iosis i from moth
e
r
.
T
risomy
16
ca
us
e
s
16
%
of th
e
first
trim
e
st
e
r mis
ca
rri
a
g
e
,
b
ut not foun
d
in
ad
v
a
n
ced
pr
e
gn
a
n
c
y
,
whil
e T
risomy
13
,
18
,
a
n
d
21
ca
n pro
d
u
ce a
vi
ab
l
e
pr
e
gn
a
n
c
y with
a
p
e
r
ce
nt
a
g
e
of
57
%
for trisomy
13
,
14
%
for
T
risomy
18
,
a
n
d
70
%
for
T
risomy
21
T
risomy
A
utosom w
a
s foun
d
n
ea
rly
50
%
in th
e ca
s
e
of spont
a
n
e
ous
ab
ortion
,
with
th
e
most
c
ommon trisomy of
16
a
n
d
r
e
l
a
t
ed
to th
e a
g
e
of moth
e
rs
.
T
his is th
e
c
hromosom
e d
isor
de
r most oft
e
n foun
d
in th
e
first trim
e
st
e
r spont
a
n
e
ous
ab
ortion
.
T
r
a
nslo
ca
tion
ca
n
a
pp
ea
r in
b
oth p
a
r
e
nts
,
whil
e ba
l
a
n
ced c
hromosom
e
inv
e
rsions
m
a
y
be
foun
d
in
c
oupl
e
s with r
e
p
ea
t
ed ab
ortion
.
T
risomy
A
utosom
,
e
x
ce
pt
C
hromosom
e N
um
be
r
1
,
ca
n o
cc
ur in spont
a
n
e
ous
ab
ortion
,
with trisomy
13
,
16
,
18
,
21
,
a
n
d
22
of th
e
most
c
ommonly foun
d
.
Ab
out
30
%
of spont
a
n
e
ous
ab
ortion
ca
s
e
s
a
r
e ca
us
ed b
y trisomy
,
whil
e
10
%
a
r
e
ca
us
ed b
y
a
monosomy of s
e
x or polyploi
d
y
c
hromosom
e
s
.
T
h
e
in
c
i
de
n
ce
of trisomy
in
c
r
ea
s
e
s with m
a
t
e
rn
a
l
a
g
e
,
whil
e
th
e
monosomy of s
e
x
a
n
d
polyploi
d
y
c
hromosom
e
s is not influ
e
n
ced b
y th
e a
g
e
of moth
e
rs
.
M
ost trisomys
a
r
e be
li
e
v
ed
to
be d
u
e
to non
-
d
isjun
c
tion
d
uring
Ma
t
e
rn
a
l
Me
iosis
.
T
risomy
16
is th
e
most
c
ommon
b
ut n
e
v
e
r r
eac
h
e
s
a
th
e
rm
a
ti
c
pr
e
gn
a
n
c
y
.
Ab
out
70
%
of
c
hromosom
a
l
ab
norm
a
liti
e
s in wom
e
n with r
e
p
ea
t
ed
spont
a
n
e
ous
ab
ortion
a
r
e de
t
ec
t
ed a
s trisomy through fish
e
x
a
min
a
tion
.
F
r
e
qu
e
nt num
e
ri
ca
l
ab
norm
a
liti
e
s
a
r
e
trisomy
,
wh
e
r
e
th
e
r
e a
r
e
thr
ee c
opi
e
s of on
e c
hromosom
e
in
ce
lls
,
pro
d
u
c
ing
a
tot
a
l of
47
c
hromosom
e
s p
e
r
ce
ll
.
F
or
e
x
a
mpl
e
,
T
risomy
21
m
ea
ns
a
ll
ce
lls h
a
v
e
thr
ee c
opi
e
s of
c
hromosom
e
21
,
e
xpr
e
ss
ed a
s
47
xx
+
21
or
47
xy
+
21
.
T
h
e
m
a
in
ca
us
e
is non
-
d
isjun
c
tion trisomy
,
wh
e
r
e
th
e c
hromosom
e
of p
a
ir f
a
ils
s
e
p
a
r
a
t
e
ly
d
uring m
e
iosis
I
or
II
,
pro
d
u
ce
s on
e c
hil
d ce
ll with
a
monosomy
(
45
c
hromosom
e
s
)
a
n
d
oth
e
r
c
hil
d
r
e
n
'
s
ce
lls with trisomy
.
N
on
-
D
isjun
c
tion
Me
iosis
Ma
t
e
rn
a
l in
c
r
ea
s
e
s
a
long with th
e a
g
e
of moth
e
rs
,
whil
e
non
-
d
isjun
c
tions of
Pa
t
e
rn
a
l m
e
iosis is not r
e
l
a
t
ed
to
a
g
e a
n
d ca
n o
cc
ur in young p
a
r
e
nts
.
A
utosom
a
l
trisomy th
a
t is most oft
e
n foun
d
in liv
e b
irths is trisomy
21
,
18
,
a
n
d
13
,
whil
e
trisomy
16
a
n
d
22
a
r
e
usu
a
lly foun
d
in spont
a
n
e
ous
ab
ortion
a
n
d
n
e
v
e
r
a
t liv
e b
irth
.
M
onosomy
X
(
45
x
)
is
ca
us
ed b
y non
-
d
isjun
c
tions
,
a
n
d
th
e
r
e
is no r
e
l
a
tionship with
th
e a
g
e
of
a c
lini
ca
lly known m
a
t
e
rn
a
l
.
M
onosomy
X
is
a
lmost impossi
b
l
e
to surviv
e
a
n
d
usu
a
lly
d
is
a
pp
ea
r
be
for
e
impl
a
nt
a
tion
.
H
ow
e
v
e
r
,
T
urn
e
r
'
s syn
d
rom
e
,
th
e
r
e
sult
of monosomy
X
,
ca
n
ca
us
e a
roun
d
20
%
of mis
ca
rri
a
g
e
s in th
e
first trim
e
st
e
r
,
e
v
e
n
though som
e
f
e
tus
e
s
ca
n surviv
e
.
M
onosomy
X
is usu
a
lly
d
u
e
to th
e
loss of s
e
x
c
hromosom
e
s from f
a
th
e
r
,
whil
e a
utosom
a
l monosomy is r
a
r
e
.
O
f th
e
4
,
969
ca
s
e
s
of mis
ca
rri
a
g
e
s stu
d
i
ed
,
2319
show
ed c
hromosom
e ab
norm
a
liti
e
s
,
with only fiv
e
a
utosomi
c
monosomy
ca
s
e
s
(
0
.
2
%
).
M
onosomy
X
o
cc
urs in
15
-
20
%
of spont
a
n
e
ous
ab
ortion
a
n
d
is usu
a
lly
acc
omp
a
ni
ed b
y n
a
rrowing of th
e c
or
d a
n
d a
nom
a
li
e
s su
c
h
a
s hygrom
a c
ysti
c a
n
d ede
m
a a
n
a
s
a
rk
a
in
ad
v
a
n
ced
pr
e
gn
a
n
c
y
.
C
hromosom
e
stru
c
tur
a
l
ab
norm
a
liti
e
s su
c
h
a
s
de
l
e
tions
,
tr
a
nslo
ca
tion
,
inv
e
rsion
,
a
n
d d
upli
ca
tion
,
e
sp
ec
i
a
lly tr
a
nslo
ca
tion
a
n
d
inv
e
rsion
,
ca
n
ca
us
e
spont
a
n
e
ous
ab
ortion
a
n
d
r
e
p
ea
t
ab
ortion
.
Ab
out
6
%
of spont
a
n
e
ous
ab
ortion
ca
s
e
s
a
r
e ca
us
ed
b
y
c
hromosom
e
stru
c
tur
a
l
ab
norm
a
liti
e
s
.
I
f on
e
of th
e
p
a
r
e
nts is
a ca
rri
e
r of th
e
stru
c
tur
a
l
ab
norm
a
lity of th
e c
hromosom
e
,
it is lik
e
ly th
a
t th
e c
hil
d b
orn h
a
s
a
norm
a
l
c
hromosom
e
or
c
hromosom
e ab
norm
a
liti
e
s
.
S
pont
a
n
e
ous
ab
ortion
d
u
e
to
c
hromosom
a
l
ab
norm
a
liti
e
s
be
g
a
n to
be
i
de
ntifi
ed
a
ft
e
r th
e de
v
e
lopm
e
nt of
c
omp
a
r
a
tiv
e
t
ec
hniqu
e
s
.
Bab
i
e
s with
ba
l
a
n
ced
tr
a
nslo
ca
tions m
a
y
be b
orn norm
a
lly
.
A
utosom monosomy is v
e
ry r
a
r
e a
n
d ca
nnot
surviv
e
.
Se
x
c
hromosom
e
polysomy
(
47
xxx or
47
xxy
)
is r
a
r
e
ly foun
d
in
ab
ortion
b
ut
mor
e
oft
e
n in
bab
i
e
s
b
orn liv
e
.
K
linf
e
lt
e
r syn
d
rom
e
(
47
XXY
)
is
a c
ommon
ca
us
e
of
m
a
l
e
inf
e
rtility with
a
roun
d
1
of
1000
liv
e b
irths
.
Ab
out h
a
lf of th
e
47
XXY
c
on
ce
ption
e
xp
e
ri
e
n
ced
spont
a
n
e
ous
ab
ortion
,
with non
-
d
isjun
c
tion
Pa
t
e
rn
a
l in
a
roun
d
50
%
of
ca
s
e
s
,
m
e
iosis i non
-
d
isjun
c
tion
a
roun
d
33
%
,
a
n
d
m
e
iosis
II
non
-
d
isjun
c
tion
a
roun
d
77
%
.
Ab
out
15
%
of th
e ca
s
e
of
K
linf
e
lt
e
r syn
d
rom
e
is
a
mos
a
i
c
,
most of
47
XXY
/
46
XY
,
usu
a
lly
d
u
e
to non
-
d
isjun
c
tion mitosis
a
t th
e
initi
a
l st
a
g
e
of
th
e e
m
b
ryo
.
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