Identification of MYOC gene mutation and polymorphism in a large Malay family with juvenile-onset open angle glaucoma

PURPOSE:
To screen for mutations in the coding region of the myocilin (MYOC) gene in a large Malay family with juvenile-onset open angle glaucoma (JOAG).

METHODS:
A total of 122 family members were thoroughly examined and screened for JOAG. Venipuncture was conducted. Genomic DNA was extracted from peripheral blood leukocytes. The presence of a mutation and a polymorphism was ascertained with PCR amplification followed by the direct sequencing technique.

RESULTS:
Thirty-two of the 122 screened family members were identified to have JOAG (11 new cases and 21 known cases). An autosomal dominant inheritance pattern with incomplete penetrance was observed. A C→A substitution at position 1440 in exon 3 that changes asparagine (AAC) to lysine (AAA) was identified in affected family members except two probands (III:5 and IV:6). Six probands were identified as having the Asn480Lys mutation but have not developed the disease yet. An intronic polymorphism IVS2 730 +35 G>A was also identified. There was a significant association between Asn480Lys (p<0.001) and IVS2 730+35G>A (p<0.001) in the affected and unaffected probands in this family.

CONCLUSIONS:
The Asn480Lys mutation and the IVS2 730+35 G>A polymorphism increased susceptibility to JOAG in this large Malay pedigree. Identifying the MYOC mutations and polymorphisms is important for providing presymptomatic molecular diagnosis.