Different WDR36 mutation pattern in Chinese patients with primary open-angle glaucoma.

PURPOSE: To determine the distribution of WD repeat domain 36 (WDR36) sequence variants in Chinese patients with primary open-angle glaucoma (POAG). METHODS: One hundred and thirty-five unrelated POAG patients (82 high tension glaucoma [HTG], 42 normal tension glaucoma [NTG], and 11 juvenile-onset POAG [JOAG] patients) and 77 unrelated controls were recruited. All 23 coding exons and splicing junctions of WDR36 were sequenced using BigDye Terminator v3.1 cycle sequencing kit. Single nucleotide polymorphism (SNP) and haplotype associations were analyzed using PLINK (version 1.04). RESULTS: Nineteen sequence alterations were identified, and eight of them were novel including two novel nonsynonymous SNPs (L240V and I713V). Except the common I264V polymorphism, no other previously reported disease-causing or disease-susceptibility mutations were found. The novel I713V mutation was observed in three (3.7%) patients with HTG. One intronic SNP, IVS5+30C>T (rs10038177), showed significantly higher frequency of minor allele T in HTG patients (16.5%) than in controls (1.3%; Odds ratio [OR]=15.0, p=7.9 x 10(-7), Bonferroni corrected p=1.5 x 10(-5)). Haplotype GTA, which is composed of rs13153937, rs10038177, and rs11241095, was significantly associated with HTG (OR=22.5, p=0.002, Bonferroni corrected p=0.013). Neither the individual SNPs nor haplotypes of WDR36 were associated with NTG or JOAG (Bonferroni corrected p>0.05). CONCLUSIONS: Findings in this study suggest WDR36 to be associated with sporadic HTG but not with NTG or JOAG. Our results also suggest a different mutation pattern of WDR36 in the Chinese population from other ethnic populations.

Fine mapping of new glaucoma locus GLC1M and exclusion of neuregulin 2 as the causative gene.

PURPOSE: We recently identified a novel glaucoma locus on 5q22.1-q32, designated as GLC1M, in a family from the Philippines with autosomal dominant juvenile-onset primary open angle glaucoma (JOAG). No mutations in myocilin (MYOC), optineurin (OPTN), and WD-repeat protein 36 (WDR36) were found. Neuregulin 2 (NRG2) is an excellent potential functional as well as positional candidate at GLC1M. The goal of the present study was to evaluate the role of the NRG2 gene in this JOAG family and unrelated JOAG patients and to refine the critical interval for GLC1M. METHODS: Genomic DNA was obtained from 27 family members. All coding exons and splicing sites of NRG2 were screened for sequence alterations by polymerase chain reaction (PCR) and DNA sequencing. A cohort of 92 unrelated JOAG patients and 92 control subjects were genotyped for the three single nucleotide polymorphisms (SNPs) of NRG2 by PCR and DNA sequencing. Haplotype and segregation analyses were performed in the family. Fisher's exact test was used to compare the frequencies of the NRG2 polymorphisms between affected and unaffected subjects in the family and between unrelated JOAG patients and control subjects. RESULTS: Three SNPs were identified: c.98G>A (S33N), IVS3+13A>G (rs889022), and c.1976A>G (G659G). None of them segregated with the JOAG phenotype in this family. No association was found between NRG2 and JOAG in the case-control study (p>0.12). However, further inspection of the haplotypes in the family localized the NRG2 gene telomeric to the disease locus. The critical interval of GLC1M was therefore refined to a region of 28 Mb between D5S2051 and NRG2. CONCLUSIONS: The linkage interval for GLC1M was refined to a smaller region. The NRG2 gene was excluded as the causative gene for JOAG.