Genetic linkage study of high-grade myopia in a Hutterite population from South Dakota
ABSTRACT Myopia is a common, complex disorder, and severe forms have implications for blindness due to increased risk of premature cataracts, glaucoma, retinal detachment, and macular degeneration. Autosomal dominant (AD) non-syndromic high-grade myopia has been mapped to chromosomes 18p11.31, 12q21-23, 17q21-23, 7q36, 2q37.1, 7p15.3, 15q12-13, 3q26, 4q12, 8p23, 4q22-q27, 1p36, and Xq23-q25. Here, we demonstrate evidence of linkage for AD non-syndromic high-grade myopia in a large Hutterite family to a locus on chromosome 10q21.1.
After clinical evaluation, genomic DNA was genotyped from 29 members of a Hutterite family from South Dakota (7 affected). The average refractive error of affected individuals was -7.04 diopters. Microsatellite markers were used to exclude linkage to the known AD nonsyndromic high-grade myopia loci as well as to syndromic high-grade myopia loci. A genome screen was then performed using 382 markers with an average inter-marker distance of 10 cM followed by fine-point mapping in all regions of the genome that gave positive LOD scores. SimWalk2 software was used for multipoint linkage based on AD and autosomal recessive (AR) models with a penetrance of 90% and a disease allele frequency of 0.001.
A maximum multipoint LOD score of 3.22 was achieved under an AD model at microsatellite marker D10S1643. Fine point mapping and haplotype analysis defined a critical region of 2.67 cM on chromosome 10q21.1. Haplotype analysis demonstrated two distinct haplotypes segregating with high-grade myopia, indicative of two distinct mutations occurring in the same gene.
We have identified a presumptive myopia locus for high-grade myopia based on linkage and haplotype analysis.
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ABSTRACT: Purpose: To evaluate variants in six genes in 298 unrelated patients with early-onset high myopia (eoHM). Methods: Genomic DNA from 298 patients with eoHM was analyzed by whole exome sequencing. Variants in LRPAP1, CTSH, LEPREL1, ZNF644, SLC39A5, and SCO2 genes were selected and analyzed with bioinformatics. Potential candidate variants were confirmed by Sanger sequencing and then validated in available family members and 192 normal controls. Results: A total of nine variants predicted to affect the functional residues were detected. The LRPAP1 gene showed a homozygous frameshift mutation (c.197delC, p.S67Qfs*8) in a consanguineous family. The ZNF644 gene showed five heterozygous missense mutations (c.1106A>T, p.K369M; c.1648G>A, p.A550T; c.2014A>G, p.S672G; c.2048G>C, p.R683T, and c.2551G>C, p.D851H) in five families, but the c.1106A>T, (p.K369M) and c.1648G>A, (p.A550T) in ZNF644 did not co-segregated with high myopia in the families. The SLC39A5 gene showed a heterozygous missense variant (c.1238G>C, p.G413A) in a sporadic individual. The SCO2 gene showed two heterozygous missense variants (c.334C>T, p.R112W and c.358C>T, p.R120W) in two families. None of the variants was detected in 192 normal controls and all were predicted to be damaging by both Polyphen-2 and SIFT, except for the reported p.S672G mutation in ZNF644, which was predicted to be benign by Polyphen-2. No homozygous or compound heterozygous variants were found in CTSH and LEPREL1. Conclusion: Our results provide additional evidence to support the idea that mutation in LRPAP1 is associated with high myopia. Further studies are expected to evaluate the pathogenicity of the variants in CTSH, LEPREL1, ZNF644, SLC39A5, and SCO2. Copyright © 2014 by Association for Research in Vision and Ophthalmology.Investigative Ophthalmology & Visual Science 12/2014; 56(1). DOI:10.1167/iovs.14-14850 · 3.66 Impact Factor
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ABSTRACT: Two recent large-scale genome-wide association studies identified significant associations between myopia and SNPs near the PRSS56, BMP3, KCNQ5, LAMA2, TOX, TJP2, RDH5, ZIC2, RASGRF1, GJD2, RBFOX1, and SHISA6 genes. Our study is to examine whether rare variants in these genes contribute to high myopia. Whole exome sequencing was performed on samples of 298 probands with early-onset high myopia (spherical refraction in each meridian ≤-6.00 D in both eyes; age of onset <7 years) and 195 controls (different forms of retinal degeneration including Leber congenital amaurosis, cone-rod dystrophy, and familial exudative vitroretinopathy). Potential variations in these genes were selected for further validation and comparison to the controls. Moreover, Sanger sequencing was used to evaluate the coding regions and the upstream 800 base pairs of GJD2 in 395 additional subjects with late-onset moderate to high myopia (loMHM) (spherical refraction in each meridian ≤-4.00 D; age of onset ≥7 years) and 403 normal controls (-0.50D-+1.00D). Exome sequencing of the 298 probands with eoHM identified 25 rare variants that were predicted to affect coding residues. The segregation analysis and the distribution of rare variants between patients and controls did not provide evidence to support their involvement in myopia. Sanger sequencing of GJD2 in an additional 395 subjects with loMHM and 403 normal controls did not identify myopia-associated variants. We did not find evidence to support the association of myopia with rare variants in these genes, probably due to our limited sample size. Additional studies are expected to validate these results. Copyright © 2015 by Association for Research in Vision and Ophthalmology.Investigative Ophthalmology & Visual Science 01/2015; 56(2). DOI:10.1167/iovs.14-14880 · 3.66 Impact Factor
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ABSTRACT: Mutations in the NYX gene are known to cause complete congenital stationary night blindness (CSNB1), which is always accompanied by high myopia. In this study, we aimed to investigate the association between NYX mutations and high myopia with or without CSNB1. Four Chinese families having high myopia with or without CSNB1 and 96 normal controls were recruited. We searched for mutations in the NYX gene using Sanger sequencing. Further analyses of the detected variations in the available family members were performed, and the frequencies of the detected variations in 96 normal controls were determined to verify our deduction. The effect of each variation on the nyctalopin protein was predicted using online tools. Four potential pathogenic variations in the NYX gene were found in four families with high myopia with or without CSNB1. Three of the four variants were novel (c.626G>C; c.121delG; c.335T>C). The previously identified variant, c.529_530delGCinsAT, was found in an isolated highly myopic patient and an affected brother, but the other affected brother did not carry the same variation. Further linkage analyses of this family showed a coinheritance of markers at MYP1. These four mutations were not identified in the 96 normal controls. Our study expands the mutation spectrum of NYX for cases of high myopia with CSNB1; however, more evidence is needed to elucidate the pathogenic effects of NYX on isolated high myopia.Molecular vision 01/2015; 21:213-23. · 2.25 Impact Factor