Medknow Publications on behalf of Indian Society of Human Genetics
Abstract
Background: Down syndrome (DS) is the most common chromosomal disorder.
It has three chromosomal patterns. Aim: To determine the cytogenetic
and comorbidity profiles of DS in the Genetic Unit of Mansoura
University Children′s Hospital, Mansoura, Egypt. Materials and
Methods: A retrospective analysis was performed on the case records of
712 cytogenetically diagnosed cases of DS at the Genetic Unit of
Mansoura University Children′s Hospital, Egypt, during a 10-year
period. Results: About 19% of the cases had one or more cardiac
anomalies and about 8% were hypothyroid. Nondisjunction was the most
common type of abnormality, followed by translocation and lastly
mosaic: 96.1, 3.1, and 0.8%, respectively. Hypothyroidism was
significantly more common in translocation and mosaic karyotypes than
in the nondisjunction karyotypes. First and second birth orders were
significantly higher in the translocation and mosaic groups than in the
nondisjunction group. Mothers are significantly older at the index
pregnancy in the nondisjunction group than in the other two groups. We
compared our findings with those of previous studies. Conclusion:
Knowing karyotype of DS will help in genetic counseling of the parents.
Wide-scale national community-based survey with DS registry could help
in estimating the size of the problem