Comparative analysis of autosomal and x-linked genes involved in nonspecific cognitive impairment

The focus of research on candidate gene identification of recessive non-syndromic cognitive impairment is increasing and to date 19 genes for X-linked and 10 autosomal non-syndromic mental retardation have been reported. The X chromosome has higher proportion of cognitive genes as compared to autosomes; but the presence of 22 autosomes and the origination of X chromosome from autosome during the course of evolution is putting a mark of question on this fact and leads to the hypothesis that the number of autosomal cognitive genes should be higher in number than the genes on X chromosome. The comparative analysis of both sets [autosomal v/s X-linked] of genes revealed significant similarities with respect to their evolutionary conservation, cellular localization, molecular and biological functions, protein domain sharing, subcellular expression profiling in nervous tissues, etc. The results and observation conclude that the knowledge of X-linked cognitive genes can be utilized in a variety of ways to explore more autosomal cognitive genes computationally

Mental retardation; molecular cytogenetic techniques used for diagnosis; a literature survey

Mental retardation, also termed as learning impairment or cognitive dysfunction, is a serious manifestation of nervous system. The defining features of mental retardation are low or subaverage intellectual functioning [Intelligence quotient<70], impairment in at least two of the adaptive skills [e.g communication ability, self care, self guidance, reading, writing ability, etc] before 18 year of age1. Molecular cytogenetics is the study of genetic disorders using advanced technologies combined with cytogenetic and molecular methodologies2. Molecular diagnosis has equal importance as clinical diagnosis in mental retardation and day by day new advancement in these methodologies are being introduced by molecular cytogeneticists. The promising achievement of molecular cytogenetic techniques is the genetic counseling of high risk pregnancies. The current mini-survey of literature discusses an overview of these techniques employed to investigate deletion, duplication, inversion and translocation of chromosomes associated with mental retardation