Analysis of SMOC2 gene variants in familial and nonfamilial primary open angle glaucoma Pakistani patients

AIM:To find out the association of secreted protein acidic and rich in cysteine(SPARC)-related modular calcium binding 2(SMOC2)gene variants rs2255680 and rs13208776 with genotypic and phenotypic characteristics in both familial and non-familial primary open angle glaucoma(POAG)patients.METHODS:A total of 212 POAG patients,comprising 124 familial and 88 non-familial,were enrolled.For genotyping the SMOC2 variant rs2255680,amplification refractory mutation system(ARMS)-polymerase chain reaction(PCR)method and PCR-restriction fragment length polymorphism(PCR-RFLP)were utilized for analyzing rs13208776 variant.RESULTS:The mean age of familial POAG patients was 50.92±9.12y,with 78 males and 46 females.The mean age of non-familial POAG patients was 53.14±13.44y,with 52 males and 36 females.The SMOC2 gene variant rs13208776 showed the significant association with POAG between familial and non-familial groups.The homozygous G/G variant was frequent among non-familial(60.2%)whereas the heterozygous G/A variant was more frequent in familial POAG patients(46%).There were significant differences in G/A variant between familial and non-familial glaucoma patients,and the risk was decreased to 0.53-fold in non-familial glaucoma patients[odds ratio(OR):0.53;95%confidence interval(CI):0.29-0.94;P=0.033]in codominant model.The risk was further reduced to 0.49-fold(95%CI:0.28-0.86;P=0.012)in dominant model for non-familial patients.No significant association of SMOC2 gene variant rs2255680 between familial and non-familial glaucoma patients was found in our population.The haplotype analysis showed the decreased risk for TA[OR:0.48(95%CI:0.29-0.79);P=0.004]and an increased risk for TG[OR=2.28(95%CI:1.22-4.25);P=0.01]haplotypes.CONCLUSION:Current findings show significant association of SMOC2 gene variant rs13208776 with POAG between familial and non-familial Pakistani patients.

Two novel variants in CYP1B1 gene: a major contributor of autosomal recessive primary congenital glaucoma with allelic heterogeneity in Pakistani patients

AIM: To find the CYP1 B1 mutations associated with primary congenital glaucoma(PCG) in Pakistani consanguineous pedigrees. METHODS: After getting informed consent, 11 consanguineous pedigrees belonging to different ethnic groups were enrolled. Detailed medical history was recorded and pedigrees were drawn. The standard ophthalmological examination was done to characterize the phenotype. Genomic DNA was extracted from 10 mL whole blood and coding exons and exon intron boundaries of CYP1 B1 gene were directly sequenced. Bioinformatics tools were used to model the mutant protein and predict the effect of novel variants on protein structure and function. RESULTS: Sequencing analysis revealed 5 different CYP1 B1 variants in 7 families(7/11; 64%), including two novel variants. A common mutation, p.R390 H was found in four families, whereas p.P437 L was found once in a family. Two novel variants, a homozygous non sense variant p.L13* and a compound heterozygous variant, p.P350 T along with p.V364 M were segregating with PCGin two families. All the patients had the variable onset and severity of the disease. The success rate of early clinical interventions was observed dependent on mutation types and position. Two different haplotypes were associated with frequently found mutation, p.R390 H. CONCLUSION: Identification of novel CYP1 B1 variants reassert the genetic heterogeneity of Pakistani PCG patients. The patients with missense mutations show severe phenotypic presentations and poor vision after surgical interventions as compare to patients with null variants. This may help to better understand the role of CYP1 B1 mutations in the development of PCG and its course of pathogenicity.