[Linkage analysis of six Algerian families with autosomal recessive non specific mental retardation]

Mental retardation is one of the most frequent major handicap, with a 1-3% frequency in the general population. The recent progress of molecular biology and cytogenetic allowed to identify new genes for non syndromic autosomal recessive mental retardation. To seek a genetic linkage to the loci implied in the nonspecific mental retardation transmitted into autosomal recessive [ARNSMR] in Algerian families with several affected members and to make the Genetic analysis of ARNSMR for 4 known loci: 3p25-pter; 4q24- q25, 19p13.12 and 1p21.1-p13. The study concerned 34 individuals including 15 patients, belonging to six consanguineous Algerian families. Genotyping was made using polymorphic microsatellite markers and the analysis carried out thanks to the program Gene Mapper software. Statistical analyses were validated using the Fast Link programme of the Easy linkage software [V4:00 betas]. The study carried out made it possible to exclude linkage of all loci for 3 families, nevertheless the linkage of one family to the locus 1p21.1-p13.3 remains possible. The absence of linkage of 4 Algerian families with autosomal recessive mental retardation to 3 well known loci, confirms the genetic heterogeneity of mental retardation. We have to pursue research of candidate genes by whole genome scan

Non-syndromic autosomal recessive mental retardation in Tunisian families: exclusion of GRIK2 and TUSC3 genes

Mental retardation is one of the most frequent major handicap, with a 1-3% frequency in the general population, it appear a major problem of public health. The recent progress of molecular biology and cytogenetic allowed to identify new genes for non syndromic autosomal recessive mental retardation [NSAR-MR]. Genetic analysis of NSAR-MR: the GRIK2 gene [6q16.3-q21] and the TUSC3 gene [8p22]. Four Tunisian families with NSAR-MR were included in this study. Genotyping was made using polymorphic microsatellite markers and statistical analysis was validated using the Fast Link programme of the Easy linkage software [V4:00beta]. Genotyping and linkage analysis excluded linkage of the GRIK2 gene and TUSC3 gene. Our results confirm the extreme genetic heterogeneity of NSAR-MR