Human Congenital Disorders: Phenotypic Clues and Karyotypic Studies

Abstract

The study of constitutional chromosome complement in patients with congenital disorders is important for clinical management of the patient, genetic counselling, and future risk assessment. The current study includes patients of uncharacterized congenital disorders (132) in whom the genetic study was done in terms of karyotyping (n=15 patients and 20 parents). The patients had various degrees of mental retardation and heterogeneous clinical presentations. The detailed phenotypic characterization was used to query the web-based tool POSSUM under clinical guidance to get a clue regarding underlying condition based on collective information and pictures of phenotypic characters. This exercise is currently a major focus of research and is called ‘deep phenotyping’. Chromosome studies were done by GTG banding following short-term cultures of peripheral blood. The karyotypes were analysed using IKAROS software (Metasystems, Germany). Out of 15 patients and 20 parents studied, majority had normal karyotype, with two patients showing commonly reported chromosomal anomaly namely pericentric inversion of Y chromosome (familial), and large satellites on chromosome 14. The POSSUM exercise for phenotypes indicated possible underlying genetic conditions and scope for further necessary analysis.