title: Absence of mutations in four genes encoding for congenital cataract and expressed in the human brain in Tunisian families with cataract and mental retardation.
abstract: BACKGROUND
  To identify the genetic defect associated with autosomal recessive congenital cataract (ARCC), mental retardation (MR) and ARCC, MR and microcephaly present in most patients in four Tunisian consanguineous families.
  
  
  METHODS
  We screened four genes implicated in congenital cataract by direct sequencing in two groups of patients; those affected by ARCC associated to MR and those who presented also microcephaly. Among its three genes PAX6, PITX3 and HSF4 are expressed in human brain and one gene LIM2 encodes for the protein MP20 that interact with the protein galectin-3 expressed in human brain and plays a crucial role in its development. All genes were screened by direct sequencing in two groups of patients; those affected by ARCC associated to MR and those who presented also microcephaly.
  
  
  RESULTS
  We report no mutation in the four genes of congenital cataract and its flanking regions. Only variations that did not segregate with the studied phenotypes (ARCC associated to MR, ARCC associated with MR and microcephaly) are reported. We detected three intronic variations in PAX6 gene: IVS4 -274insG (intron 4), IVS12 -174G>A (intron12) in the four studied families and IVS4 -195G>A (intron 4) in two families. Two substitutions polymorphisms in PITX3 gene: c.439 C>T (exon 3) and c.930 C>A (exon4) in one family. One intronic variation in HSF4 gene: IVS7 +93C>T (intron 7) identified in one family. And three intronic substitutions in LIM2 gene identified in all four studied families: IVS2 -24A>G (intron 2), IVS4 +32C>T (intron 4) and c.*15A>C (3'-downstream sequence).
  
  
  CONCLUSIONS
  Although the role of the four studied genes: PAX6, PITX3, HSF4 and LIM2 in both ocular and central nervous system development, we report the absence of mutations in all studied genes in four families with phenotypes associating cataract, MR and microcephaly.
authors: University Tunis Elmanar, Laboratoire Génétique Humaine, Tunis, Tunisia.
authors: Manèl
authors: M
authors: Chograni
authors: Myriam
authors: M
authors: Chaabouni
authors: Faouzi
authors: F
authors: Mâazoul
authors: Hedi
authors: H
authors: Bouzid
authors: Abdelhafid
authors: A
authors: Kraiem
authors: Habiba B Bouhamed
authors: HB
authors: Chaabouni
mesh_terms: D000293:Adolescent; D000328:Adult; D002386:Cataract / Q000150:complications / Q000151:congenital* / Q000235:genetics*; D002648:Child; D003241:Consanguinity; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics*; D005136:Eye Proteins / Q000235:genetics*; D005190:Family; D005260:Female; D005787:Gene Frequency; D000076249:Heat Shock Transcription Factors; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D008607:Intellectual Disability / Q000150:complications* / Q000235:genetics*; D007438:Introns / Q000235:genetics; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008831:Microcephaly / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D014416:Tunisia; D055815:Young Adult
chemical_list: D004268:DNA-Binding Proteins; D005136:Eye Proteins; C102948:HSF4 protein, human; D000076249:Heat Shock Transcription Factors; D018398:Homeodomain Proteins; C044539:LIM2 protein, human; D008565:Membrane Proteins; D014157:Transcription Factors