Cytogenetic variations in a series of cases of Down Syndrome

Abstract

IntroductionDown Syndrome (DS) is generally associated with mental retardation and developmental delay. The occurrence of DS is associated with multiple factors like maternal age, consanguineous marriage, early induced abortion etc. Chances of recurrences of DS in next pregnancy depend on the genetic constitution of the affected individual and the parents. So this study was done to find out the different types of cytogenetic abnormalities in DS patients and also the association of parental age to DS in a population in West Bengal. It is hoped that the present study will emphasize the need for genetic counseling of prospective parents as well as parents of individuals affected with DS, together with cytogenetic screening of pregnancies which are at high risk for DS. MethodsA cytogenetic analysis was performed using conventional GTG banding on 120 patients with clinical features of DS, referred to the Department of Genetics, Vivekananda Institute of Medical Sciences, Kolkata during the period from October, 2008 to September, 2014. ResultsCytogenetic analysis confirmed the diagnosis of DS in 117 cases, among them regular trisomy constituted 83.76%, mosaicism recorded in 11.11% and Robertsonian translocation in 5.12% of cases. The mean maternal age was higher in regular trisomy 21 (25.08 yrs) than in translocation (22.50 yrs). No significant difference was noted in mean paternal age among different categories of DS cases. DiscussionThis study documents the types of cytogenetic abnormalities in DS children of West Bengal population of India and thus emphasizes the need for genetic counseling in these cases.