Pattern of cytogenetic abnormalities in syndromic mental retardation/intellectual disability in Kashmir region of Jammu and Kashmir

Abstract Objective In mental retardation/intellectual disability, genetic etiologies have been conventionally identified in about 40% of cases and chromosomal aberrations stand as the most prevalent genetic abnormality associated with it. So far, neither the frequency nor the nature of chromosomal abnormalities among patients with syndromic ID in this region of India is clear. Therefore, the present study was designed to identify the most common types of chromosomal abnormalities in syndromic intellectually disabled patients of Kashmir and to compare our results with those of similar studies reported elsewhere. Methods Cytogenetic analysis was carried out on 266 children diagnosed with intellectual disability with syndromic facies.Cytogenetic analysis was performed by using the GTG banding technique. Results Cytogenetic analysis revealed chromosomal abnormalities in 69.17% of the selected cases. Free trisomy 21 was found to be the most common (84.23%) cytogenetic anomaly in these cases. Besides, mosaic trisomy 21 was observed in 9.78% of cases while 3.26% of the cases had trisomy 21 as a robertsonian translocation. Also cases with 47,XY, +21, t(5;19)(q13;q13.3) karyotype, 47,XX, +21, t(11;12)(11q12;12q24.2) karyotype and 47,XY, +21, inv9(p12;q13) karyotype, 46, XY, dup (21q22-qter) karyotype were observed. Conclusion The cytogenetic analysis of intellectual disability cases of the present study reveals trisomy 21 as a major contributor in the syndromic mental retardation cases of Kashmir. Besides, the frequency of free trisomy of chromosome 21 and advanced maternal age in the syndromic cases of our study is much higher as compared to that reported by different studies across India.