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Primary role of CYP1B1 in Indian juvenile-onset POAG patients
Moulinath Acharya1, Suddhasil Mookherjee, Ashima Bhattacharjee
1Human Genetics & Genomics Division, Indian Institute of Chemical Biology, Kolkata, India.
Insights
Mutations in the CYP1B1 gene were identified in some primary open-angle glaucoma (POAG) patients, suggesting it may rarely cause juvenile onset POAG (JOAG) through monogenic inheritance. Screening for CYP1B1 mutations is important in JOAG patients lacking other known mutations.
Area of Science:
- Genetics
- Ophthalmology
- Molecular Biology
Background:
- The cytochrome P450 superfamily enzyme, CYP1B1, is linked to primary congenital glaucoma (PCG).
- Emerging evidence suggests CYP1B1 may act as a modifier locus in primary open-angle glaucoma (POAG).
Purpose of the Study:
- To investigate the potential role of CYP1B1 in POAG patients.
- To identify allelic variants in CYP1B1 associated with POAG.
Main Methods:
- Genomic DNA from 200 Indian POAG patients and 100 controls was analyzed.
- The coding sequence of CYP1B1 was amplified using PCR and subjected to direct DNA sequencing.
Main Results:
- Six mutations in CYP1B1 were found in nine POAG patients, with no mutations detected in controls.
- One novel homozygous mutation (R523T) and five heterozygous mutations (three reported, two novel) were identified.
- A homozygous mutation in a familial juvenile onset POAG case cosegregated with the disease, indicating autosomal recessive inheritance. Novel mutations were in a region distinct from PCG-associated mutations.
- Single nucleotide polymorphisms (SNPs) in CYP1B1 were observed in both POAG patients and controls.
Conclusions:
- CYP1B1 mutations can rarely be the primary cause of juvenile onset POAG (JOAG) via monogenic association.
- Genetic screening of CYP1B1 is recommended for JOAG patients negative for mutations in previously identified POAG candidate genes.
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.
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