Chromosomal variants and genetic diseases

Abstract

Genetic diseases, also called hereditary diseases, are the most burdensome of all human afflictions. Genetic diseases are determined at conception but can be expressed at any time of life. Roughly, 1 out of 20 children admitted to hospital has disorder which is entirely genetic in origin and such disorders account for about one out of ten childhood deaths in hospital. A number of surveys have indicated that at least 1 out of 50 newborn has a major congenital abnormality and 1 out of 200 has a major chromosomal abnormality.[1] This issue of the journal documents several such anomalies as isolated case reports. The incidence of chromosomal abnormalities is many times greater in spontaneous abortions than among live births. In early spontaneous abortions over 50% have a chromosomal abnormality; however, 10–15% chromosomal abnormalities reported in couples with recurrent spontaneous abortions. In case of stillbirths and neonatal deaths between 6 and 7% have a chromosomal abnormality. This indicates that the majority of chromosomal abnormalities present at conception are lethal in early pregnancy or later and only a small proportion of all such abnormalities is exhibited in live births. Advancement in cytogenetic technology using fluorescence in situ hybridization (FISH) helped us to detect microchromosomal rearrangements and low-grade mosaicism. There are three types of chromosomal variations; mosaicism, heteromorphism, single cell translocations commonly seen in routine chromosomal analysis. There is one article in this issue (Dubey et al.), where authors reported