J. F. Hejtmancik

Rapamycin slows aging in mice

Rapamycin increases lifespan in mice, but whether this represents merely inhibition of lethal neoplastic diseases, or an overall slowing in multiple aspects of aging is currently unclear. We report here that many forms of age‐dependent change, including alterations in heart, liver, adrenal glands, endometrium, and tendon, as well as age‐dependent decline in spontaneous activity, occur more slowly in rapamycin‐treated mice, suggesting strongly that rapamycin retards multiple aspects of aging in mice, in addition to any beneficial effects it may have on neoplastic disease. We also note, however, that mice treated with rapamycin starting at 9 months of age have significantly higher incidence of testicular degeneration and cataracts; harmful effects of this kind will guide further studies on timing, dosage, and tissue‐specific actions of rapamycin relevant to the development of clinically useful inhibitors of TOR action.

Novel locus for X linked recessive high myopia maps to Xq23–q25 but outside MYP1

Background: High myopia is a common genetic variation in most cases, affecting 1–2% of people, and is the fourth most common disorder causing blindness worldwide. Six autosomal dominant loci and one X-linked recessive locus have been reported, but no genes responsible for high myopia have been identified. Objective: To report a Chinese family in which six males presented with high myopia consistent with an X linked recessive trait. Results: Affected individuals shared three common features: high myopia, reduced visual acuity, and fundal changes of high myopia. Protan and deutan were observed in the family, but they did not co-segregate with the high myopia phenotype. X-chromosome-wide linkage analysis mapped the high myopia locus to a 25 cM (14.9 Mb) region on Xq23–q25 between DXS1210 and DXS8057, with maximum two point lod scores at θ = 0 of 2.75 and 2.29 for DXS1001 and DXS8059, respectively. Conclusions: This new myopia locus is outside the linked region of the first high myopia locus (MYP1). Refinement of the linkage region with additional families and screening candidate genes for mutation may lead to the identification of the defect gene.

Patterns of open-angle glaucoma in the Barbados Family Study

OBJECTIVE To describe the Barbados Family Study of open-angle glaucoma (OAG) and present risk factors for OAG in siblings of study probands. DESIGN Observational study of families of probands with OAG. PARTICIPANTS Two hundred thirty probands and 1056 relatives (from 207 families). METHODS Probands and their family members underwent standardized examinations, including automated perimetry, applanation tonometry, ophthalmologic evaluation, fundus photography, blood pressure, interview, and genotyping. Generalized estimation equation methods were used to evaluate risk factors. MAIN OUTCOME MEASURES Presence of OAG in the relatives, as defined by both visual field and optic disc findings, after ophthalmologic exclusion of other causes. RESULTS The median ages of probands and relatives were 68 and 47 years, respectively. In the 207 families, 29% of the probands had one relative with OAG and 10% had two or more relatives affected. Of the 1056 family members, 10% had OAG, 13% had suspect OAG, and 6% had ocular hypertension. One fifth of the 338 siblings had OAG (n = 67); they tended to be older and more often were male. Multivariate comparisons between siblings with and without OAG found that age, higher intraocular pressure (IOP), myopia, and lower diastolic blood pressure-IOP differences were related to OAG, whereas hypertension and diabetes were not. CONCLUSIONS Based on standardized protocols and examinations, approximately one quarter of the relatives had OAG or suspected OAG, despite their relatively young age. Risk factors for OAG in siblings were similar to risk factors in unrelated individuals. Analyses are ongoing to determine OAG inheritance and to localize potential gene(s) involved.

Autosomal recessive corneal endothelial dystrophy (CHED2) is associated with mutations in SLC4A11

Objective: To map and identify the gene for autosomal recessive congenital hereditary endothelial dystrophy (CHED2, OMIM 217700), a disorder characterised by diffuse bilateral corneal clouding that may lead to visual impairment and requiring corneal transplantation. Methods: Members of 16 families with autosomal recessive CHED were genotyped for 13 microsatellite markers at the CHED2 locus on chromosome 20p13-12. Two-point linkage analysis was carried out using the FASTLINK version of the MLINK program. Mutation screening was carried out by amplification of exons and flanking regions by polymerase chain reaction, followed by direct automated sequencing. Results: Linkage and haplotype analysis placed the disease locus within a 2.2 cM (1.3 Mb) interval flanked by D20S198 and D20S889, including SLC4A11. The maximum limit of detection score of 11.1 was obtained with D20S117 at θ = 0. Sequencing of SLC4A11 showed homozygotic mutations in affected members from 12 of 16 families. Conclusion: These results confirm that mutations in the SLC4A11 gene cause autosomal recessive CHED.

Identification of novel missense mutations in the Norrie disease gene associated with one X‐linked and four sporadic cases of Familial Exudative Vitreoretinopathy

X‐linked Familial Exudative Vitreoretinopathy (XLFEVR) is a hereditary eye disorder that affects both the retina and the vitreous body. It is characterized by an abnormal vascularization of the peripheral retina. It has been previously shown by linkage and candidate gene analysis that XLFEVR and Norrie disease are allelic. In this report we describe four novel mutations (R41K, H42R, K58N, and Y120C) in the Norrie disease gene associated with one X‐linked and four sporadic cases of FEVR. One mutation (H42R) was found to be segregating with the disease in three generations (X‐linked family), and the others are sporadic. These sequence alterations changed the encoded amino acids in the Norrie disease protein and were not found in 17 unaffected family members or in 36 randomly selected normal individuals. This study provides additional evidence that mutations in the same gene can result in FEVR and Norrie disease. It also demonstrates that it may be beneficial for clinical diagnosis to screen for mutations in the Norrie disease gene in sporadic FEVR cases. Hum Mutat 9:396–401, 1997.

Anticipation in myotonic dystrophy: I. Statistical verification based on clinical and haplotype findings

To determine whether anticipation in myotonic dystrophy (DM) is a true biologic phenomenon or an artifact of ascertainment bias, we studied 201 members of nine DM kindreds, including 67 individuals with the clinical diagnosis of DM. Of 49 parent-child pairs in which both the parents and the children were clinically affected, the onset of DM occurred in an earlier decade of life in the child than the parent in 44 pairs and in the same decade in five pairs (p < 0.001). To eliminate direct ascertainment bias, we excluded nine pairs involving the index patients. Indirect ascertainment bias due to incomplete penetrance was unlikely, since 55% of the children of DM parents had DM. Howeveip, by haplotype analysis of restriction fragment length polymorphisms, we diagnosed DM in one of the 42 asymptomatic children of affected parents and excluded DM in twenty-eight. We estimated that patients with early-onset DM would have produced an additional 25 DM children if they had normal fertility and nuptiality. Assuming that the expected age-of-onset distribution occurs without anticipation in these 25, only seven would have had the onset of DM earlier than their parents. With the corrected result, the child would have been affected earlier than the parent in 53 pairs, and the parent would have been affected at the same age as or earlier than the child in 13 pairs (p ≤ 0.001). Thus, the observed anticipation is unlikely to be totally attributable to ascertainment bias, suggesting the potential importance of biologic mechanisms.

EPHA2 Polymorphisms and Age-Related Cataract in India

Objective We investigated whether previously reported single nucleotide polymorphisms (SNPs) of EPHA2 in European studies are associated with cataract in India. Methods We carried out a population-based genetic association study. We enumerated randomly sampled villages in two areas of north and south India to identify people aged 40 and over. Participants attended a clinical examination including lens photography and provided a blood sample for genotyping. Lens images were graded by the Lens Opacification Classification System (LOCS III). Cataract was defined as a LOCS III grade of nuclear ≥4, cortical ≥3, posterior sub-capsular (PSC) ≥2, or dense opacities or aphakia/pseudophakia in either eye. We genotyped SNPs rs3754334, rs7543472 and rs11260867 on genomic DNA extracted from peripheral blood leukocytes using TaqMan assays in an ABI 7900 real-time PCR. We used logistic regression with robust standard errors to examine the association between cataract and the EPHA2 SNPs, adjusting for age, sex and location. Results 7418 participants had data on at least one of the SNPs investigated. Genotype frequencies of controls were in Hardy-Weinberg Equilibrium (p>0.05). There was no association of rs3754334 with cataract or type of cataract. Minor allele homozygous genotypes of rs7543472 and rs11260867 compared to the major homozygote genotype were associated with cortical cataract, Odds ratio (OR) = 1.8, 95% Confidence Interval (CI) (1.1, 3.1) p = 0.03 and 2.9 (1.2, 7.1) p = 0.01 respectively, and with PSC cataract, OR = 1.5 (1.1, 2.2) p = 0.02 and 1.8 (0.9, 3.6) p = 0.07 respectively. There was no consistent association of SNPs with nuclear cataract or a combined variable of any type of cataract including operated cataract. Conclusions Our results in the Indian population agree with previous studies of the association of EPHA2 variants with cortical cataracts. We report new findings for the association with PSC which is particularly prevalent in Indians.

exomeSuite: Whole exome sequence variant filtering tool for rapid identification of putative disease causing SNVs/indels

Exome and whole-genome analyses powered by next-generation sequencing (NGS) have become invaluable tools in identifying causal mutations responsible for Mendelian disorders. Given that individual exomes contain several thousand single nucleotide variants and insertions/deletions, it remains a challenge to analyze large numbers of variants from multiple exomes to identify causal alleles associated with inherited conditions. To this end, we have developed user-friendly software that analyzes variant calls from multiple individuals to facilitate identification of causal mutations. The software, termed exomeSuite, filters for putative causative variants of monogenic diseases inherited in one of three forms: dominant, recessive caused by a homozygous variant, or recessive caused by two compound heterozygous variants. In addition, exomeSuite can perform homozygosity mapping and analyze the variant data of multiple unrelated individuals. Here we demonstrate that filtering of variants with exomeSuite reduces datasets to a fraction of a percent of their original size. To the best of our knowledge this is the first freely available software developed to analyze variant data from multiple individuals that rapidly assimilates and filters large data sets based on pattern of inheritance.

Evaluation of Genetic Polymorphisms in Clusterin and Tumor Necrosis Factor-Alpha Genes in South Indian Individuals with Pseudoexfoliation Syndrome

Abstract Purpose: The aim of this study was to explore the potential association of genetic variants across clusterin (CLU) and tumor necrosis factor-alpha (TNF-α) genes in South Indian individuals with pseudoexfoliation syndrome (PEXS) and pseudoexfoliation glaucoma (PEXG). Materials and Methods: A total of 523 individuals including 299 unrelated cases (150 PEXS and 149 PEXG) and 224 age- and ethnically-matched healthy controls were recruited for genetic analysis. Six single-nucleotide polymorphisms (SNPs) including, five CLU SNPs (rs11136000, rs2279590, rs9331888, rs9331931, rs3087554) and one promoter SNP (rs1800629) of TNF-α were genotyped in all study subjects. Genotyping of CLU SNPs were performed using the TaqMan allelic discrimination assay while TNF-α SNP was genotyped using polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) analysis. Association analysis was performed by determining the distributions of genotype and allele frequencies, Hardy–Weinberg equilibrium, and chi-square p values and odds ratios as implemented in the Golden Helix SNP & Variation Suite (SVS). Results: Five CLU SNPs did not show any significant differences in allele frequencies between patients and control subjects (rs3087554, p = 0.919, OR = 1.01, 95% CI: 0.77–1.33; rs2279590, p = 0.432, OR = 1.12, 95% CI: 0.84–1.51; rs9331931, p = 0.310, OR = 1.24, 95% CI: 0.81–1.89; rs11136000, p = 0.072, OR = 1.31, 95% CI: 0.97–1.76; rs9331888, p = 0.911, OR = 1.01, 95% CI: 0.78–1.31). The investigation of TNF-α SNP established a significant association with PEXS and PEXG (p = 0.042, OR = 0.61, 95% CI: 0.38–0.99). However, this association did not remain significant after Bonferroni correction. Conclusions: Our data suggest that genetic variants in CLU and TNF-α genes do not play a major role in the development of PEXS and PEXG in the South Indian population.

Prevalence and association of refractive anisometropia with near work habits among young schoolchildren: The evidence from a population-based study

Background Lifestyle behaviour may play a role in refractive error among children, but the association between near work habits and refractive anisometropia remains unclear. Methods We estimated the prevalence of refractive anisometropia and examined its association with near work activities among 23,114 children in the Myopia Investigation Study in Taipei who were grade 2 elementary school students at baseline in 2013 and 2014. Baseline data on demographics, medical history, parental history and near work habits were collected by parent-administered questionnaire survey. Refractive status was determined by cycloplegic autorefraction. Refractive anisometropia was defined as the spherical equivalent difference ≥ 1.0 diopter between eyes. Results The prevalence of refractive anisometropia was 5.3% (95% confidence interval [CI], 5.0% to 5.6%). The prevalence and severity of refractive anisometropia increased with both myopic and hyperopic refractive error. Multivariate logistic regression analysis revealed that refractive anisometropia was significantly associated with myopia (odds ratio [OR], 2.98; 95% CI, 2.53–3.51), hyperopia (OR, 2.37; 95% CI, 1.98–2.83), degree of astigmatism (OR, 1.005; 95% CI, 1.005–1.006), amblyopia (OR, 2.54; 95% CI, 2.06–3.12), male gender (OR, 0.88; 95% CI, 0.78–0.99) and senior high school level of maternal education (OR, 0.69; 95% CI, 0.52–0.92). Though anisometropic children were more likely to spend more time on near work (crude OR, 1.15; 95% CI, 1.02–1.29) and to have less eye-to-object distance in doing near work (crude OR, 1.15; 95% CI, 1.01–1.30), these associations became insignificant after additional adjustment for ocular, demographic and parental factors. Conclusions The present study provides large-scale, population-based evidence showing no independent association between refractive anisometropia and near work habits, though myopia is associated with refractive anisometropia.