Cytogenetic profile of Down syndrome in Alexandria, Egypt

Abstract

During 1992-2001, 673 Down syndrome patients were referred to the Department of Human Genetics in Alexandria. Regular [‎free]‎ trisomy 21 constituted 95.4% of cases; Robertsonian translocation 2.7%; and mosaicism 0.7%. In 8 cases, regular trisomy 21 was associated with structural or numerical chromosome anomalies. Translocation was parentally inherited for 33.3% of cases and maternal transmission was twice as common as paternal. Two translocated Down syndrome fetuses were diagnosed prenatally in at [‎14;21]‎ carrier mother. Mean maternal age was high in regular trisomy 21 [‎38.2 years]‎ but not in translocation [‎25.3 years]‎. There was an excess of males in all groups except the mosaic group where the male:female ratio was 0.67. Cytogenetic investigations assist in patient management and family counselling