Karyotypic and Phenotypic Study of Patients with Idiopathic Mental Retardation and Dysmorphism

Abstract

The study of constitutional chromosome in patients with mental retardation is important for clinical management of the patient, genetic counseling, future risk assessment and preventive measures and for better prognosis. This study includes 17 patients with uncharacterized mental retardation whose genetic study were done in terms of Karyotyping. These patients had various degree of mental retardation and wide range of dysmorphic features. Phenotypic characterizations were done with the help of web based tool phenomizer. This was done with collective data of picture of phenotypic characters. This exercise is currently a major focus of research and is called ‘deep phenotyping’. Chromosome studies were done by short-term peripheral blood culture followed by GTG banding. The karyotypes were analyzed using software Leica CW4000. For the study of uncharacterized mental retardation, syndromic condition must be ruled out in all patients. Fragile X syndrome is one of the major causes of MR which was ruled out in all patients by Genotyping. Out of 17, 16 patients have normal karyotype and 1 has mosaicism in trisomy 13. The Phenomizer exercise for phenotypes indicates specific genes which are relevant to specific syndrome that is useful for further genetic diagnosis.