Fine mapping of MRT9 locus through genome wide homozygosity mapping in a consanguineous Pakistani family.

ABSTRACT

Intellectual disability (ID) or Mental Retardation (MR) is a broad term, which occupies several medical directions. It is extremely heterogeneous and has about reported 25,000 genes of which half of the genes expression have been found in the brain. Intellectual disability causes severe disability and has a worldwide prevalence of around 2% while autosomal recessive form of ID causes almost 25% of all non syndromic (NS) ID cases. A consanguineous family (who will be referred as) MR7 with phenotype of ID was sampled in Swat region of Pakistan. All affected individuals in the family were observed having a low IQ and cognitive mutilation with no sign of biochemical, skeletal or neurological abnormalities. Their dc-ribonucleic acid (DNA) was extracted and subjected to STS (Single tagged sequence) marker analyses which showed exclusion of all known non syndromic autosomal recessive (NS-AR) ID genes. In the family MR7, autozygosity mapping was performed by microarray single-nucleotide polymorphism analysis in all the collected samples, for a close examination of the homozygous region in all the affected however no homozygosity was observed for the normal parent. In this consanguineous family of Pakistan, autozygosity mapping showed linkage interval (chr14 30,294,526- 32,106,658) overlapping with already reported MRT9 locus (chr1426,578,608-32,780,288) for NS- ARID.