Abstracto

Down syndrome: a cytogenetic study in North Indian population

Priyanka Pandey, Rakesh Kumar Verma, Navneet Kumar, Sciddhartha Koonwar

Down syndrome constitutes the most common chromosomal abnormality among live births (1 in 730 live births) and most frequent form of intellectual disability. Genetic cause for this syndrome is trisomy of chromosome 21. The cytogenetic profile of Down syndrome includes free trisomy 21, Robertsonian translocations, mosaicism, duplication of the DS critical region and other structural rearrangements involving chromosome 21. Purpose of the study was to confirm the clinical diagnosis of suspected cases of Down syndrome by karyotyping and to evaluate several risk factors associated with trisomy 21 among patients belonging to Lucknow region. Karyotype analysis was done in 46 patients with clinical suspicion of Down syndrome. GTG banding was done according to standard protocols. Findings: out of 46 cases i.e., 43 (93.5%) had abnormal karyogram. All these 43 cases had trisomy 21 (Down's syndrome). Among patients with Down syndrome, free trisomy (n=40; 93%) was most common followed by Robertsonian translocation (n=2; 4.7%) and mosaic trisomy (n=1; 2.3%) respectively. Majority of patients were males (n=27; 62.7%) and there were 16 (37.3%) females. Male to female ratio of Down syndrome patients was 1.68. 50% of patients with Down syndrome were born to mothers falling in age group of 36-40 y. Identification of various types of chromosomal abnormalities in Down syndrome is very important. It aids in management of these children and to aware the affected families about recurrence risk and options available.