Primary role of CYP1B1 in Indian juvenile-onset POAG patients

Abstract

Purpose: CYP1B1, a member of the cytochrome P450 superfamily of enzymes, has been implicated in primary congenital glaucoma (PCG). Recent studies suggest a role of CYP1B1 in primary open-angle glaucoma (POAG) as a modifier locus. The purpose of the study was to further investigate the potential role of CYP1B1 in POAG patients.

Methods: Two hundred unrelated Indian POAG patients and 100 unrelated ethnically matched controls were enrolled in this study. The coding sequence of CYP1B1 was amplified by polymerase chain reaction (PCR) from genomic DNA, followed by direct DNA sequencing to identify the allelic variants.

Results: Six mutations were identified in nine patients and none of the controls examined. One novel mutation (R523T) was detected in the homozygous condition while three reported (W57C, E229K, and R368H) and two novel mutations (S515L and D530G) were found in the heterozygous state. The homozygous mutation of a conserved residue, detected in a familial juvenile onset POAG (JOAG) patient (lacking MYOC or OPTN mutations), cosegregated with the disease locus in an autosomal recessive mode of transmission. All the novel mutations (R523T, S515L and D530G) were detected in a region of CYP1B1 that did not harbor any of the 34 point mutations implicated in PCG. In addition, six previously reported (p.R48G, p.A119S, p.V432L, p.D449D, p.N453S, and 372-12C>T in intron 1) and four novel (p.V395V, p.P400P, p.V518A, and c.2016C>G in the 3'-UTR) single nucleotide polymorphism (SNPs) were also observed in POAG patients and controls.

Conclusions: Our observation suggests that on rare occasions CYP1B1 may be primarily responsible for JOAG by possible monogenic association, and this observation emphasizes the importance of screening for mutation in this gene of JOAG patients that are determined not to harbor mutations in previously characterized candidate genes and loci for POAG.