Cytogenetic Study of Down Syndrome In Algeria: Report and Review

Abstract

Background: Down syndrome (DS) is the most common type of chromosomal trisomy found in new-born. It’s associated with mental retardation and characteristic facial features. A clinical diagnosis of Down syndrome may be unconfirmed in one third of cases. Objective: This study was conducted to confirm the clinical diagnosis of suspected cases with Down syndrome by a cytogenetic analysis and to evaluate several risk factors associated with trisomy 21 in a group of patients from West region of Algeria, Tlemcen. Materials and method: Karyotype analysis was carried out for 22 patients with the clinical diagnosis of Down syndrome. GTG- band and RTG-band have been made according to the standard protocols. Results: Among the 22 cases with Down syndrome, Free trisomy 21 was presented in 20 cases (91%). One case (4.5%) had translocation Down syndrome. One other case had mosaic Down syndrome. There was an excess of male than female; sex ratio was 1.75:1. The mean maternal age at birth of the affected children was 36.27 ± 7.59 years. It was significantly higher than this of mothers of non-trisomic children (27.83 ± 6.34 years; p=0.0002). Higher parity was an important risk factor associated with trisomy 21, 81% of affected children were of last or second last birth order. Paternal age and consanguinity had no effect. Conclusion: The identification of specific types of chromosomal abnormalities in Down syndrome children is very significant. It greatly helped in the management of these children and to make aware the affected families about the recurrence risk and the options available.