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gineco
ro
genetică
Analiza citogenetică şi consilierea
genetică la pacienţii cu sindrom Down
Cytogenetic analysis and genetic counseling of
patients with Down syndrome
Vasilica Plaiaşu
1
, Gabriela Motei
1
, Florina Nedelea
2
, Elena Neagu
3
, Amalia Costin
1
1 Department of Medical Genetics, IOMC “Prof Dr Alfred Rusescu”, Bucharest
2 Materno-Fetal Medical Department - Clinical Hospital “Filantropia”, Bucharest
3 DNA Laboratory - National Legal Medicine Institute “Mina Minovici”, Bucharest
Abstract
Objective.The aim of this study was to confirm in the birth order. Though advanced mater-
the presence of Down syndrome (DS) using cy- nal age is an established risk factor for DS,
togenetic testing and to assess the inheritance this study revealed an increased number of
using parental karyotype, as a basis for predict- DS babies born to the young mothers.
ing the risk of recurrence and for genetic coun- Conclusion. Karyotypes collected from chil-
seling. dren and their parents, family history and
Study design. A total of 114 cases suspected parental ages had a crucial contribution in
to have Down syndrome were included dur- providing genetic counseling, prenatal diag-
ing a period of 18 months from the Depart- nosis and estimating the risk for the next con-
ment of Medical Genetics of IOMC “Prof Dr ception. Prenatal diagnosis should be offered
Alfred Rusescu”. All this 114 cases suspected to all mothers at risk: > 35 years or younger
to have Down syndrome undergo clinical as- mothers, if the karyotype analysis indicates
sessment. Samples were collected and cytoge- an altered chromosomal pattern. Prenatal
netic analysis was performed in 96 patients. cytogenetic analysis from chorionic villi or
Results. Chromosomal abnormalities were amniotic fluid could provide early and reli-
confirmed in all of the patients that were able diagnosis, and help the family to avoid
analyzed by cytogenetic techniques. Most of the recurrence.
the children with DS were born to mothers Keywords: Down syndrome, karyotype, tri-
under 35 years old and were the second born somy, mosaicism, translocation, counseling
Introduction have widely recognized characteristic for maternal meiotic nondisjunction.
Down syndrome (DS) is a chromo- appearance. The head may be smaller However, understanding of the basic
somal abnormality characterized by than normal and abnormally shaped. mechanism behind the maternal age
the presence of an extracopy of gene- Typical facial features include a flat- effect is lacking: with a maternal age
tic material on the 21 chromosome, tened nose, protruding tongue and of 35 years, the risk is 1 in 385 and in-
either in whole (trisomy 21) or part upward slanting eyes with epicanthal creases over this age.[2]
(such as due to translocation), which fold.[1] These change with age. The Types of chromosomal alteration for
causes delays in the way a child deve- hands are short and broad with short Down syndrome
lops and often leads to mental retar- fingers, and they often have a single a. Trisomy 21 is the cause of approxi-
dation. While some kids with DS have crease in the palm. Normal growth and mately 95% of observed Down syndro-
no other health problems, others may development is usually retarded. mes and is usually caused by meiotic
experience a lot of medical issues that The frequency of trisomy 21 in the nondisjunction in the gametes prior
require extra care. population is 1 in 650 to 1,000 live birt- to conception, and all cells in the body
Despite the variability in Down syn- hs. Advanced maternal age remains are affected. With nondisjunction,
drome, children with Down syndrome the only well-documented risk factor a gamete (i.e., a sperm or egg cell) is
pag. 170 Vol. 4, Nr. 3 /septembrie 2008
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