CYP1B1 gene mutations causing primary congenital glaucoma in Tunisia
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Published on: June 3, 2018
Yosra Bouyacoub1, Salim Ben Yahia, Nesrine Abroug
1Université Tunis El Manar, Institut Pasteur de Tunis, LR11IPT05, Biomedical Genomics and Oncogenetics Laboratory, 1002, Tunis, Tunisia; Université de Monastir, Institut Supérieur de Biotechnologie, Monastir, 5000, Tunisia.
Insights
Genetic mutations in CYP1B1 are common in Tunisian children with primary congenital glaucoma (PCG). Identifying these CYP1B1 variations aids in early diagnosis and prevention of childhood blindness.
Area of Science:
- Genetics
- Ophthalmology
- Molecular Biology
Background:
- Primary congenital glaucoma (PCG) is a leading cause of childhood blindness in Tunisia.
- Genetic diagnosis is crucial for early prevention strategies.
- The cytochrome P450, family 1, subfamily B, polypeptide 1 (CYP1B1) gene is implicated in PCG.
Purpose of the Study:
- To determine the frequency of CYP1B1 mutations in Tunisian PCG patients.
- To identify novel CYP1B1 mutations associated with PCG.
- To analyze CYP1B1 haplotypes and their correlation with migratory patterns.
Main Methods:
- Genomic DNA extraction from 18 PCG patients from Central and Southern Tunisia.
- Direct sequencing of the coding regions of the CYP1B1 gene.
- Phylogenetic network analysis using the median-joining algorithm for haplotype construction.
Main Results:
- A "tetra-allelic mutation" (novel p.F231I and p.P437A) was identified in one patient.
- Previously described mutations (p.G61E and c.535delG) were found in 7 and 2 patients, respectively.
- CYP1B1 mutations were present in 55% of Tunisian PCG patient alleles; haplotype analysis revealed migratory patterns.
Conclusions:
- CYP1B1 mutations are a significant genetic cause of PCG in Tunisia.
- Identification of these mutations improves genetic diagnosis and counseling for PCG.
- Haplotype analysis provides insights into population genetics and historical migrations.
Abstract:
Primary congenital glaucoma (PCG) is responsible for a significant proportion of childhood blindness in Tunisia. Early prevention based on genetic diagnosis is therefore required. This study sought to determine the frequency of CYP1B1 (cytochrome P450, family 1, subfamily B, polypeptide 1) mutations in 18 PCG patients, recruited from Central and Southern of Tunisia. Genomic DNA was extracted and the coding regions of CYP1B1 were analysed by direct sequencing. A phylogenetic network of CYP1B1 haplotypes was drawn using the median-joining algorithm. Sequence analysis revealed a "tetra-allelic mutation" (two novel mutations, p.F231I and p.P437A in the homozygous state) in one patient. The healthy members of his family carried those variations on the same allele. Two previously described mutations p.G61E and c.535delG were also identified in the homozygous state in seven and two probands, respectively. Seven single-nucleotide polymorphisms were identified and used to generate haplotypes. Our results showed that the CYP1B1 mutations were present in 55% of Tunisian PCG patients' alleles. Haplotype analysis allowed us to define the proto-haplotype and to confirm historical migratory flows. Establishment of PCG genetic aetiology in Tunisia will improve genetic diagnosis and counselling.
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