Background: To identify the genetic defect associated with autosomal recessive congenital cataract (ARCC),\r\nmental retardation (MR) and ARCC, MR and microcephaly present in most patients in four Tunisian consanguineous\r\nfamilies.\r\nMethods: We screened four genes implicated in congenital cataract by direct sequencing in two groups of\r\npatients; those affected by ARCC associated to MR and those who presented also microcephaly. Among its three\r\ngenes PAX6, PITX3 and HSF4 are expressed in human brain and one gene LIM2 encodes for the protein MP20 that\r\ninteract with the protein galectin-3 expressed in human brain and plays a crucial role in its development. All genes\r\nwere screened by direct sequencing in two groups of patients; those affected by ARCC associated to MR and\r\nthose who presented also microcephaly.\r\nResults: We report no mutation in the four genes of congenital cataract and its flanking regions. Only variations\r\nthat did not segregate with the studied phenotypes (ARCC associated to MR, ARCC associated with MR and\r\nmicrocephaly) are reported. We detected three intronic variations in PAX6 gene: IVS4 -274insG (intron 4), IVS12\r\n-174G>A (intron12) in the four studied families and IVS4 -195G>A (intron 4) in two families. Two substitutions\r\npolymorphisms in PITX3 gene: c.439 C>T (exon 3) and c.930 C>A (exon4) in one family. One intronic variation in\r\nHSF4 gene: IVS7 +93C>T (intron 7) identified in one family. And three intronic substitutions in LIM2 gene identified\r\nin all four studied families: IVS2 -24A>G (intron 2), IVS4 +32C>T (intron 4) and c.*15A>C (3�-downstream sequence).\r\nConclusion: Although the role of the four studied genes: PAX6, PITX3, HSF4 and LIM2 in both ocular and central\r\nnervous system development, we report the absence of mutations in all studied genes in four families with\r\nphenotypes associating cataract, MR and microcephaly.
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