Screening of common CYP1B1 mutations in Iranian POAG patients using a microarray-based PrASE protocol

Area of Science:

• Ophthalmology
• Genetics
• Molecular Biology

Background:

• The cytochrome P4501B1 (CYP1B1) gene is a known cause of primary congenital glaucoma (PCG) in Iranians and is implicated in juvenile-onset open-angle glaucoma (JOAG).
• Primary open-angle glaucoma (POAG) is a significant cause of irreversible blindness worldwide.

Purpose of the Study:

• To investigate the role of CYP1B1 mutations in a larger cohort of Iranian primary open-angle glaucoma (POAG) patients, including late-onset cases.
• To develop and validate a microarray-based protocol for efficient mutation screening of CYP1B1.

Main Methods:

• A cohort of 63 POAG patients, 9 affected family members, and 33 PCG patients underwent clinical examinations.
• A microarray-based protocol using multiplexed allele-specific amplification (PrASE) and sequence-tagged primers was developed to screen specific CYP1B1 mutations (G61E, R368H, R390H, R469W).
• The entire coding sequences of CYP1B1 and myocilin (MYOC) were sequenced, and intragenic SNP haplotypes were determined for mutated alleles.

Main Results:

• The microarray-based PrASE methodology showed 100% concordance with sequencing results.
• Seven POAG patients (11.1%) carried CYP1B1 mutations, with a higher prevalence in juvenile-onset (5/21) compared to late-onset (2/42) cases.
• Four of the seven mutation-carrying patients had two mutated alleles, and no MYOC mutations were found.

Conclusions:

• The PrASE microarray approach is a reliable and efficient tool for simultaneous genotyping and screening common mutations in large populations.
• CYP1B1 mutations are implicated in Iranian POAG, especially the juvenile-onset form.
• The high frequency of patients carrying two mutated CYP1B1 alleles in the Iranian population warrants further investigation.