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Table.2 Effect of maternal age on Down syndrome
Free trisomy Translocation Mosaicism
Maternal age
cases without
karyotype
Total
No. % No. % No. %
< 35 years 53 55.21 10 10.42 2 1.04 10 74
> 35 years 27 28.13 1 1.04 1 2.08 6 36
? age * 2 2.08 0 0 0 0 2 4
TOTaL
96 cases with 82 11 3 18 114
karyotype
* Information not available because of the abandon of the child
Birth order of Down syndrome re- born to mother’s <35 years age. In case
vealed a high frequence of second of translocation 10,42 % were born to
borns (41,23%) followed by first borns mother <35 years age. The mean ma-
(34,21%) and 24,56% are from famili- ternal age of free trisomy DS cases was
es with three and more children. Only estimated to be 33.43 years and for
one case is from twins. translocation was 26.54 years.
Familial inheritance in robertsoni- Our cases report also associated
an translocation was seen only in one malformations of Down syndrome.
case, whereas the remaining is arisen Among them, heart defects have oc-
as de novo. One case with t(14;21) curred more frequently. Individuals
( fig.2) showed maternal inheritance. with Down syndrome had specific
The mother being a carrier of balanced major congenital heart malformati-
Fig.3. Karyotype of the
chromosomal rearrangement ( fig.3), ons: atrioventricular canal, ventri-
mother carrier with t(14;21)
the risk of recurrence of birth of a child cular septal defect, atrial septal de- 8 If father carries Robertsoni-
with chromosomal imbalance is incre- fect, patent ductus arteriosus, and an translocation involving 21, e.g.
ased. Counseling for the risk of recur- of the gastrointestinal tract, such as rob(14q21q), risk is <1%
rence of DS children is necessary once duodenal stenosis. Other associated 8 If parent carries rob(21q21q)
the carrier for such balanced chromo- anomalies: cleft palate, congenital translocation, risk approaches 100%
somal rearrangement is identified. hypothyroidism, genitalia abnorma- 8 If a woman with Down syndro-
Maternal age at conception is an im- lities (cryptorchidism, epispadias, me, 47,XX,+21, becomes pregnant,
portant factor in genetic counseling. hypospadias, hypertrophic clitoris, the risk of +21 in the offspring is
Maternal ages of children with Down ophthalmic disorders (nystagmus, ~50% ( fertility in man with +21 is ex-
syndrome at the time of conception strabismus, asimetric palpebral fis- ceptionally rare).
were available for only 110 cases out sures), orthopedic problems.
of 114 cases studied. It is obvious from Chromosomal investigations, fami- Prenatal Screening
the present data that 55,21 % free tri- ly history, pedigree analysis, paren-
and Diagnosis
somy Down syndrome children were tal ages and parental karyotypes are
essential factors in offering genetic There are two types of prenatal tests
counseling, estimating the risk for the available to detect Down syndrome in
next conception.[5] a fetus: screening tests and diagnostic
8 Some women who have had a tri- tests.
somy 21 conception may have a small 8 Screening tests estimate the risk
increased risk for other aneuploidies. that a fetus has DS. They are noninva-
8 De novo Robertsonian transloca- sive and include:
tion – risk is low, but recurrence has - nuchal translucency testing
been reported - the double and triple test
8 If mother carries Robertsoni- - detailed ultrasounds
an translocation involving 21, e.g. 8 Diagnostic tests can tell whether
Fig.2. Karyotype of DS child with t(14;21)
rob(14q21q), risk is 10-15% the fetus actually has the condition.
pag. 172 Vol. 4, Nr. 3 /septembrie 2008
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