Grant: Operating Grant

Mental retardation is believed to occur with a prevalence of approximately 2% within the population. Autosomal recessive forms of non-syndromic mental retardation (where no additional symptoms are presnet and the disease causimg mutation is inherited from both unaffected parents) are believed to account for a large proportion of these individuals. Mapping genes for autosomal recessive disorders can be performed with great efficiency in families with a high proportion of consanguineous marriages using microarray data for high-density DNA markers. We have recruited in total 57 consanguineous families with MR (autistic individuals are also present in some families) from Pakistan - a country where consanguineous marriages are commonplace. We propose to simultaneously map the disease loci and genes in these families, while refining the clinical descriptions for each family. To date we have mapped and identified the disease genes for 4 families, including 2 new, and two previously known genes. We also plan to recruit additional Pakistani MR families to the study.