[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.