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01.12.2011 | Research article | Ausgabe 1/2011 Open Access

BMC Ophthalmology 1/2011

Absence of mutations in four genes encoding for congenital cataract and expressed in the human brain in Tunisian families with cataract and mental retardation

Zeitschrift:
BMC Ophthalmology > Ausgabe 1/2011
Autoren:
Manèl Chograni, Myriam Chaabouni, Faouzi Mâazoul, Hedi Bouzid, Abdelhafid Kraiem, Habiba B Bouhamed Chaabouni
Wichtige Hinweise

Electronic supplementary material

The online version of this article (doi:10.​1186/​1471-2415-11-35) contains supplementary material, which is available to authorized users.

Competing interests

The authors declare that they have no competing interests.

Authors' contributions

MC carried out thechoice of genes, the molecular genetic study, the sequence alignement and drafted the manuscript, MyC participated in the choice of the gene, FM carried out the examination of the patients, HB: participated in the clinical study of the patients, AK: carried out the ophthalmologic examination of the other patients and HBC conceived of the study, and participated in its design and coordination and helped to draft the manuscript.
All authors read and approved the final manuscript.

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).

Conclusion

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.
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