Chromosomal analysis and maternal age risk in some Down syndrome patients

Chromosomal analysis was done on 50 clinically diagnosed Down syndrome patients. The karyotype analysis revealed that 88% (44 of 50 cases) with trisomy 21, having three copies of chromosome 21. In 2% (one case) translocation was observed, one copy of chromosome 21 was translocated to another chromosome 21 and in 10% (5 cases) there was a mosaicism for a trisomic. The higher percentage (72%) of cases was found between 21-34 years. 26% of cases were found with ages above 35 years. Only 2% of cases were found with maternal age between18-20 years and Down syndrome is more frequent in males than in females.