Cytogenetic Study of Cases of Down Syndrome in Gujarat

Down syndrome (DS) or trisomy 21 can be caused by three types of chromosomal abnormalities: trisomy 21, translocation or mosaicism. The cytogenetic diagnosis, made through karyotype examination, is important mainly to determine recurrence risks to assist genetic counseling. The aim of this study was to carry out a cytogenetic profile of 26 clinically diagnosed cases of DS attending Pediatrics Outpatient Department (OPD) and admitted in Pediatrics ward, Civil Hospital, Ahmedabad as well as cases from B.M. Institute of Mental Health, Ashram road, Ahmedabad with the purpose of establishing the nature of the chromosomal abnormalities of these patients. 26 clinically diagnosed DS patients were selected, their blood samples were taken and their karyotypes were prepared at Genetics Laboratory at B.J. Medical college, Ahmedabad. Karyotype analysis revealed that, out of 26 cases trisomy 21 was found in 19 (73%) case, normal karyotype was found in 7(27%) cases and not a single case of translocation and mosaicism was found. Nondisjunction was the main cause of Down syndrome, as the majority of the patients have trisomy of chromosome 21. The cytogenetic pattern of Down syndrome is variable among different studies. So cytogenetic analysis of suspected DS is of value to objectively confirm the diagnosis & to provide a basis for genetic counseling.