[Study of genetic mutation locus in a family with congenital aniridia].

OBJECTIVE: The aim of this study was to determine the genetic mutation locus of congenital aniridia. METHODS: Peripheral vein blood (2-5 ml) was collected from all members of a congenital aniridia family. DNA was extracted, then, the primers of polymorphic microsatellite genetic markers were synthesized, followed by polymerase chain reaction (PCR) analysis. Polyacrylamide gel electrophoresis (PAGE) was used to analyze the denatured PCR products and haplotype linkage analysis was applied according to the relationship between bands and family members to determine the association between the phenotype of aniridia and PAX6 gene. Fourteen exons of human PAX6 gene were amplified by PCR and allele specific variations were detected by single strand conformation polymorphism (SSCP). By comparing the difference of bands between patients and the unaffected members, the mutated exons was detected. The mutated locus was detected by direct DNA automated sequencing of the PCR products with different SSCP bands. RESULTS: PAX6 mutation was linked to the occurrence of aniridia in this family. An extra band corresponding to exon 9 in PAX6 was found by single strand conformational polymorphism analysis in all aniridia patients in this family, but not detected in the unaffected members. A mutation of C to T was detected by sequencing at the nucleotide 1080 that converts the Arg codon (CGA) to a termination codon (TGA). CONCLUSION: Mutation of PAX6 gene can result in the occurrence of congenital aniridia.

Mutation analysis of PAX6 gene in a large Chinese family with aniridia.

BACKGROUND: Mutations in PAX6 gene have been shown to be the genetic cause of aniridia, which is a severe panocular eye disease characterised by iris hypoplasia. However, there is no study to do genetic analysis of aniridia, although there are several case reports in China. Here, we describe a mutation analysis of PAX6 in a large Chinese family with aniridia. METHODS: Genomic DNA from venous blood samples was prepared. Haplotype analysis was performed with two genetic markers (D11S904 and D11S935). Fourteen exons of the PAX6 gene were amplified from genomic DNA. Polymerase chain reaction (PCR) products of each exon were analysed by single strand conformational polymorphism (SSCP). The PCR products having an abnormal pattern were sequenced to confirm the mutation. RESULTS: Significant evidence for allele sharing in affected patients was detected suggesting that PAX6 mutation links to aniridia in this family. An extra band corresponding to exon 9 in PAX6 was found by single strand conformational polymorphism analysis in all the aniridia patients in this family, but not detected in the unaffected members. A mutation of C to T was detected by sequencing at the nucleotide 1080 that converts the Arg codon (CGA) to the termination codon (TGA). CONCLUSIONS: Aniridia is caused by a nonsense mutation of PAX6 gene in the large Chinese kindred. Genetic test is important to prevent the transmission of aniridia to their offsprings in the kindred by prenatal diagnosis.

[PAX6 mutation caused brain abnormalities in humans].

OBJECTIVE: To investigate the association between PAX6 mutation and brain abnormalities. METHODS: The brain structures of 18 affected patients and 6 normal controls in a large pedigree with a PAX6 mutation (c1080C-->T)were scanned with MRI assessing. RESULTS: Most of the affected patients showed brain abnormalities such as corpus callosum degeneration, broad cerebral ventricle grooves and broad olfactory grooves. CONCLUSION: Genetic defect of PAX6 gene may result in brain abnormalities.