Fluid-induced lung injury-role of TRPV4 channels.

Administration of bolus intravenous fluid is associated with respiratory dysfunction and increased mortality, findings with no clear mechanistic explanation. The objective of this study was to examine whether bolus intravenous (i.v.) fluid administration results in acute lung injury in a rat model and further, to examine whether this injury is associated with transient receptor potential vallinoid (TRPV)4 channel function and endothelial inflammatory response. Healthy male Sprague-Dawley rats were administered 60 ml/kg 0.9% saline i.v. over 30 min. Manifestation of acute lung injury was assessed by lung physiology, morphology, and markers of inflammation. The role of TRPV4 channels in fluid-induced lung injury was subsequently examined by the administration of ruthenium red (RR) in this established rat model and again in TRPV4 KO mice. In endothelial cell culture, permeability and P-selectin expression were measured following TRPV4 agonist with and without antagonist; 0.9% saline resulted in an increase in lung water, lavage protein and phospholipase A2, and plasma angiopoietin-2, with worsening in arterial blood oxygen (PaO2), lung elastance, surfactant activity, and lung histological injury score. These effects were ameliorated following i.v. fluid in rats receiving RR. TRPV4 KO mice did not develop lung edema. Expression of P-selectin increased in endothelial cells following administration of a TRPV4 agonist, which was ameliorated by simultaneous addition of RR. Bolus i.v. 0.9% saline resulted in permeability pulmonary edema. Data from ruthenium red, TRPV4 KO mice, and endothelial cell culture suggest activation of TRPV4 and release of angiopoietin 2 and P-selectin as the central mechanism.

Topical Application of Fingolimod Perturbs Cutaneous Inflammation.

The prevalence of allergies, including rhinitis, eczema, and anaphylaxis, is rising dramatically worldwide. This increase is especially problematic in children who bear the greatest burden of this rising trend. Increasing evidence identifies neutrophils as primary perpetrators of the more severe and difficult to manage forms of inflammation. A newly recognized mechanism by which neutrophils are recruited during the early phase of histamine-induced inflammation involves the sphingosine kinase (SK)/sphingosine-1-phosphate axis. This study examines whether topical application of fingolimod, an established SK/sphingosine-1-phosphate antagonist already in clinical use to treat multiple sclerosis, may be repurposed to treat cutaneous inflammation. Using two mouse models of ear skin inflammation (histamine- and IgE-mediated passive cutaneous anaphylaxis) we topically applied fingolimod prophylactically, as well as after establishment of the inflammatory response, and examined ear swelling, SK activity, vascular permeability, leukocyte recruitment, and production of proinflammatory mediators. The present study reveals that when applied topically, fingolimod attenuates both immediate and late-phase responses to histamine with reduced extravasation of fluid, SK-1 activity, proinflammatory cytokine and chemokine production, and neutrophil influx and prevents ear swelling. Intravital microscopy demonstrates that histamine-induced neutrophil rolling and adhesion to the postcapillary venules in the mouse ears is significantly attenuated even after 24 h. More importantly, these effects are achievable even once inflammation is established. Translation into humans was also accomplished with epicutaneous application of fingolimod resolving histamine-induced and allergen-induced inflammatory reactions in forearm skin. Overall, this study demonstrates, to our knowledge for the first time, that fingolimod may be repurposed to treat cutaneous inflammation.

Examining the Role of Sphingosine Kinase-2 in the Regulation of Endothelial Cell Barrier Integrity.

OBJECTIVE: A key mediator of vascular EC barrier integrity, S1P, is derived from phosphorylation of sphingosine by the SK-1 and SK-2. While previous work indicates that SK-1 can regulate EC barrier integrity, whether SK-2 has a similar role remains to be determined. METHODS: A cell impedance assay was used to assess human umbilical vein EC and bone marrow EC barrier integrity in vitro, with application of the SK inhibitors ABC294640, PF543, SKi, and MP-A08. In vivo studies were conducted using intravital microscopy to assess EC barrier integrity in SK-1 (Sphk1(-/-)) and SK-2 (Sphk2(-/-)) knock-out mice. RESULTS: Only ABC294640 and MP-A08, which can both inhibit SK-2, caused a decrease in EC barrier integrity in vitro in both cell types. Intravital microscopy revealed that Sphk1(-/-) mice had reduced EC barrier integrity compared to WT mice, whereas no change was evident in Sphk2(-/-) mice. CONCLUSIONS: Our data suggest that in vitro inhibition of SK-2, can compromise the integrity of the EC monolayer, while SK-1 exerts a more dominant control in vivo. These data may have clinical implications and could aid in the development of new treatments for disorders of vascular barrier function.

Ocular expression and distribution of products of the POAG-associated chromosome 9p21 gene region.

It has recently been shown that there are highly significant associations for common single nucleotide polymorphisms (SNPs) near the CDKN2B-AS1 gene region at the 9p21 locus with primary open angle glaucoma (POAG), a leading cause of irreversible blindness. This gene region houses the CDKN2B/p15(INK4B) , CDKN2A/p16(INK4A) and p14ARF (rat equivalent, p19(ARF) ) tumour suppressor genes and is adjacent to the S-methyl-5'-thioadenosine phosphorylase (MTAP) gene. In order to understand the ocular function of these genes and, therefore, how they may be involved in the pathogenesis of POAG, we studied the distribution patterns of each of their products within human and rat ocular tissues. MTAP mRNA was detected in the rat retina and optic nerve and its protein product was localised to the corneal epithelium, trabecular meshwork and retinal glial cells in both human and rat eyes. There was a very low level of p16(INK4A) mRNA present within the rat retina and slightly more in the optic nerve, although no protein product could be detected in either rat or human eyes with any of the antibodies tested. P19(ARF) mRNA was likewise only present at very low levels in rat retina and slightly higher levels in the optic nerve. However, no unambiguous evidence was found to indicate expression of specific P19(ARF)/p14(ARF) proteins in either rat or human eyes, respectively. In contrast, p15(INK4B) mRNA was detected in much higher amounts in both retina and optic nerve compared with the other genes under analysis. Moreover, p15(INK4B) protein was clearly localised to the retinal inner nuclear and ganglion cell layers and the corneal epithelium and trabecular meshwork in rat and human eyes. The presented data provide the basis for future studies that can explore the roles that these gene products may play in the pathogenesis of glaucoma and other models of optic nerve damage.

Genome-wide association analyses identify multiple loci associated with central corneal thickness and keratoconus.

Central corneal thickness (CCT) is associated with eye conditions including keratoconus and glaucoma. We performed a meta-analysis on >20,000 individuals in European and Asian populations that identified 16 new loci associated with CCT at genome-wide significance (P < 5 × 10(-8)). We further showed that 2 CCT-associated loci, FOXO1 and FNDC3B, conferred relatively large risks for keratoconus in 2 cohorts with 874 cases and 6,085 controls (rs2721051 near FOXO1 had odds ratio (OR) = 1.62, 95% confidence interval (CI) = 1.4-1.88, P = 2.7 × 10(-10), and rs4894535 in FNDC3B had OR = 1.47, 95% CI = 1.29-1.68, P = 4.9 × 10(-9)). FNDC3B was also associated with primary open-angle glaucoma (P = 5.6 × 10(-4); tested in 3 cohorts with 2,979 cases and 7,399 controls). Further analyses implicate the collagen and extracellular matrix pathways in the regulation of CCT.

The p53 codon 72 PRO/PRO genotype may be associated with initial central visual field defects in caucasians with primary open angle glaucoma.

BACKGROUND: Loss of vision in glaucoma is due to apoptotic retinal ganglion cell loss. While p53 modulates apoptosis, gene association studies between p53 variants and glaucoma have been inconsistent. In this study we evaluate the association between a p53 variant functionally known to influence apoptosis (codon 72 Pro/Arg) and the subset of primary open angle glaucoma (POAG) patients with early loss of central visual field. METHODS: Genotypes for the p53 codon 72 polymorphism (Pro/Arg) were obtained for 264 POAG patients and 400 controls from the U.S. and in replication studies for 308 POAG patients and 178 controls from Australia (GIST). The glaucoma patients were divided into two groups according to location of initial visual field defect (either paracentral or peripheral). All cases and controls were Caucasian with European ancestry. RESULTS: The p53-PRO/PRO genotype was more frequent in the U.S. POAG patients with early visual field defects in the paracentral regions compared with those in the peripheral regions or control group (p=2.7 × 10(-5)). We replicated this finding in the GIST cohort (p  =7.3 × 10(-3), and in the pooled sample (p=6.6 × 10(-7)) and in a meta-analysis of both the US and GIST datasets (1.3 × 10(-6), OR 2.17 (1.58-2.98 for the PRO allele). CONCLUSIONS: These results suggest that the p53 codon 72 PRO/PRO genotype is potentially associated with early paracentral visual field defects in primary open-angle glaucoma patients.

Genetic investigation into the endophenotypic status of central corneal thickness and optic disc parameters in relation to open-angle glaucoma.

PURPOSE: To ascertain if single nucleotide polymorphisms (SNPs) involved in the determination of central corneal thickness, optic disc area, and vertical cup-to-disc ratio (VCDR) also are associated with open-angle glaucoma (OAG). DESIGN: Retrospective case-control genetic association study. METHODS: A total of 16 SNPs associated with central corneal thickness, optic disc area, and VCDR were genotyped in 876 OAG cases and 883 normal controls. To determine if the SNPs were also correlated with OAG severity, the cohort was stratified into advanced OAG (n = 326) and nonadvanced OAG (n = 550). Both the cases and controls were of European descent and were recruited from within Australia. RESULTS: Two VCDR SNPs were found to be significantly associated with OAG after correction for multiple testing. The 2 SNPs were rs10483727, found adjacent to the SIX1 gene (P = 6.2 × 10(-06); odds ratio, 1.38; 95% confidence interval, 1.20 to 1.59), and rs1063192, found within the CDKN2B gene (P = 2.2 × 10(-05); odds ratio, 0.74; 95% confidence interval, 0.64 to 0.85). The CDKN2B variant rs1063192 also was found to be associated more strongly with advanced OAG. CONCLUSIONS: The findings from this study indicate that variants influencing VCDR are also risk alleles for OAG in our Australian cohort of European descent. The identification of SIX1 and CDKN2B as susceptibility loci will assist in understanding the pathologic mechanisms involved in the development of OAG.

Association of genetic variants in the TMCO1 gene with clinical parameters related to glaucoma and characterization of the protein in the eye.

PURPOSE: Glaucoma is the leading cause of irreversible blindness worldwide. Primary open angle glaucoma (POAG) is the most common subtype. We recently reported association of genetic variants at chromosomal loci, 1q24 and 9p21, with POAG. In this study, we determined association of the most significantly associated single nucleotide polymorphism (SNP) rs4656461, at 1q24 near the TMCO1 gene, with the clinical parameters related to glaucoma risk and diagnosis, and determined ocular expression and subcellular localization of the human TMCO1 protein to understand the mechanism of its involvement in POAG. METHODS: Association of SNP rs4656461 with five clinical parameters was assessed in 1420 POAG cases using linear regression. The TMCO1 gene was screened for mutations in 95 cases with a strong family history and advanced disease. Ocular expression and subcellular localization of the TMCO1 protein were determined by immunolabeling and as GFP-fusion. RESULTS: The data suggest that individuals homozygous for the rs4656461 risk allele (GG) are 4 to 5 years younger at diagnosis than noncarriers of this allele. Our data demonstrate expression of the TMCO1 protein in most tissues in the human eye, including the trabecular meshwork and retina. However, the subcellular localization differs from that reported in other studies. We demonstrate that the endogenous protein localizes to the cytoplasm and nucleus in vivo and ex vivo. In the nucleus, the protein localizes to the nucleoli. CONCLUSIONS: This study shows a relationship between genetic variation in and around TMCO1 with age at diagnosis of POAG and provides clues to the potential cellular function/s of this gene.

Ethnic and mouse strain differences in central corneal thickness and association with pigmentation phenotype.

The cornea is a transparent structure that permits the refraction of light into the eye. Evidence from a range of studies indicates that central corneal thickness (CCT) is strongly genetically determined. Support for a genetic component comes from data showing significant variation in CCT between different human ethnic groups. Interestingly, these studies also appear to show that skin pigmentation may influence CCT. To validate these observations, we undertook the first analysis of CCT in an oculocutaneous albinism (OCA) and Ugandan cohort, populations with distinct skin pigmentation phenotypes. There was a significant difference in the mean CCT of the OCA, Ugandan and Australian-Caucasian cohorts (Ugandan: 517.3±37 µm; Caucasian: 539.7±32.8 µm, OCA: 563.3±37.2 µm; p<0.001). A meta-analysis of 53 studies investigating the CCT of different ethnic groups was then performed and demonstrated that darker skin pigmentation is associated with a thinner CCT (p<0.001). To further verify these observations, we measured CCT in 13 different inbred mouse strains and found a significant difference between the albino and pigmented strains (p = 0.008). Specific mutations within the melanin synthesis pathway were then investigated in mice for an association with CCT. Significant differences between mutant and wild type strains were seen with the nonagouti (p<0.001), myosin VA (p<0.001), tyrosinase (p = 0.025) and tyrosinase related protein (p = 0.001) genes. These findings provide support for our hypothesis that pigmentation is associated with CCT and identifies pigment-related genes as candidates for developmental determination of a non-pigmented structure.

Common genetic variants near the Brittle Cornea Syndrome locus ZNF469 influence the blinding disease risk factor central corneal thickness.

Central corneal thickness (CCT), one of the most highly heritable human traits (h(2) typically>0.9), is important for the diagnosis of glaucoma and a potential risk factor for glaucoma susceptibility. We conducted genome-wide association studies in five cohorts from Australia and the United Kingdom (total N = 5058). Three cohorts were based on individually genotyped twin collections, with the remaining two cohorts genotyped on pooled samples from singletons with extreme trait values. The pooled sample findings were validated by individual genotyping the pooled samples together with additional samples also within extreme quantiles. We describe methods for efficient combined analysis of the results from these different study designs. We have identified and replicated quantitative trait loci on chromosomes 13 and 16 for association with CCT. The locus on chromosome 13 (nearest gene FOXO1) had an overall meta-analysis p-value for all the individually genotyped samples of 4.6x10(-10). The locus on chromosome 16 was associated with CCT with p = 8.95x10(-11). The nearest gene to the associated chromosome 16 SNPs was ZNF469, a locus recently implicated in Brittle Cornea Syndrome (BCS), a very rare disorder characterized by abnormal thin corneas. Our findings suggest that in addition to rare variants in ZNF469 underlying CCT variation in BCS patients, more common variants near this gene may contribute to CCT variation in the general population.

Candidate gene study to investigate the genetic determinants of normal variation in central corneal thickness.

PURPOSE: The genetic component underlying variation in central corneal thickness (CCT) in the normal population remains largely unknown. As CCT is an identified risk factor for open-angle glaucoma, understanding the genes involved in CCT determination could improve our understanding of the mechanisms involved in this association. METHODS: To identify novel CCT genes, we selected eight different candidates based on a range of criteria. These included; aquaporin 1 (AQ1), aquaporin 5 (AQ5), decorin (DCN), fibrillin-1 (FBN1), keratocan (KERA), lumican (LUM), osteoglycin (OGN), and paired box 6 (PAX6). Tagging single nucleotide polymorphisms (SNPs) selected from the HapMap database were genotyped to cover the majority of genetic variation within each gene. Each SNP was screened in a large, population-based cohort from Australia and both single SNP and haplotype analyses were undertaken. RESULTS: Two SNPs were found to be nominally associated with CCT, rs17352842 from FBN1 (p=0.02) and rs3026398 from PAX6 (p=0.02), although neither of these p values survived correction for multiple testing. Haplotype analysis revealed one haplotype within FBN1 (corrected p=0.048) and two haplotypes within PAX6 (strongest corrected p=0.006) associated with CCT. No other SNPs or haplotypes from the remaining genes showed any significant correlation with CCT. CONCLUSIONS: Results from this study suggest that FBN1 and PAX6 are potentially involved in determining CCT. This is the first published study to investigate these genes for association with normal CCT variation.

Novel quantitative trait loci for central corneal thickness identified by candidate gene analysis of osteogenesis imperfecta genes.

Osteogenesis imperfecta (OI) is a rare connective tissue disorder caused by mutations in the type I collagen genes, COL1A1 and COL1A2, and is characterised by low bone mass and bone fragility. In this study, we explored the relationship between type 1 collagen genes and the quantitative trait central corneal thickness (CCT). CCT was measured in a cohort of 28 Australian type I OI patients and mean CCT was found to be significantly lower compared to a normal population (P < 0.001). We then investigated CCT and corneal collagen fibril diameter and density in a mouse model of OI with a col1a2 mutation. Mean CCT was significantly lower in mutant mice (P = 0.002), as was corneal collagen fibril diameter (P = 0.034), whilst collagen fibril density was significantly greater in mutants (P = 0.034). Finally, we conducted a genetic study to determine whether common single nucleotide polymorphisms (SNPs) in COL1A1 and COL1A2 are associated with CCT variation in the normal human population. Polymorphism rs2696297 (P = 0.003) in COL1A1 and a three SNP haplotype in COL1A2 (P = 0.007) were all significantly associated with normal CCT variation. These data implicate type 1 collagen in the determination of CCT in both OI patients and normal individuals. This provides the first evidence of quantitative trait loci that influence CCT in a normal population and has potential implications for investigating genes involved in glaucoma pathogenesis, a common eye disease in which the severity and progression is influenced by CCT.

Heritability of central corneal thickness in nuclear families.

PURPOSE: Many ocular parameters show strong heritable tendencies. The significance of central corneal thickness (CCT) in the context of glaucoma has been the subject of much debate recently, but its heritability has not been extensively explored. This study was designed to investigate the parent-child heritability of CCT among groups who have CCT considered to be at the extreme ends of the normal range. METHODS: Index cases were recruited through a tertiary referral center if their CCT was greater than 578 microm (thick) or less than 510 microm (thin), representing +/-1 SD from a previously published meta-analysis mean of 544 microm (34 microm SD). Subsequently, CCT was measured in all available family members of the index cases. Family units were then analyzed to establish the degree of heritability of CCT from parent to child. RESULTS: Thirty-three index cases were included in the analysis (10 >1 SD and 23 <1 SD from the meta-analysis CCT mean). The mean CCT of the children of index cases with a CCT more than 1 SD from the mean (n = 15) and less than 1 SD from the mean (n = 40) was 568 microm (32 microm SD) and 521 microm (22 microm SD), respectively (t = 6.14; P < 0.0001). The parent-child heritability estimate for CCT was h(2) = 0.68 (95% CI, 0.64-0.73). CONCLUSIONS: These results indicate that CCT shows strong parent-child heritability, with offspring likely to demonstrate CCT similar to the parental index case.

Functional and structural implications of the complement factor H Y402H polymorphism associated with age-related macular degeneration.

PURPOSE: A Tyr-to-His (Y402H) sequence variant in the factor H (FH) and factor H-like protein (FHL-1) gene is strongly associated with an increased susceptibility for age-related macular degeneration (AMD). The purpose of this study was to understand how the Y402H variant in FH/FHL-1 contributes to the pathogenesis of AMD and, in particular, whether interactions mediated by FH/FHL-1, including binding to C-reactive protein (CRP), group A streptococcal M protein (GAS M6), heparin, and retinal pigment epithelial cells (RPE), are affected. METHODS: FH was purified from sera of patients homozygous for FH(Y402) or (H402), and recombinant FH fragments representing FHL-1 were generated. Proteins were analyzed for binding to CRP, GAS M6, heparin, and RPE cells. RESULTS: Binding of the FH and FH1 to seven polymorphic variants to CRP and M protein was reduced. The variant did not influence the interaction of FH with heparin but did reduce binding of FHL-1. Binding of the FH and FHL-1 polymorphic variant to RPE cells was not affected. CONCLUSIONS: The FH Y402H polymorphism associated with AMD causes a reduction in binding of FH and FHL-1 to CRP and M protein. Both variants show comparable binding to RPE cells, indicating that AMD is unlikely to manifest as a result of impaired host cell-surface recognition. The decreased interaction between FH and CRP, which is essential for the anti-inflammatory function of CRP, provides a possible pathophysiological explanation for the association of the Y402H variant with AMD.

Ancestral LOXL1 variants are associated with pseudoexfoliation in Caucasian Australians but with markedly lower penetrance than in Nordic people.

Pseudoexfoliation syndrome is a generalized disorder of the extracellular matrix, characterized by the pathological accumulation of abnormal fibrillar material in the anterior segment of the eye predisposing to glaucomatous optic neuropathy. We investigated the role of lysyl oxidase-like 1(LOXL1) sequence variation in a Caucasian Australian population-based cohort of 2508 individuals, 86 (3.4%) of whom were diagnosed with pseudoexfoliation syndrome. Two non-synonymous variants in exon 1 of LOXL1 (Arg141Leu;Gly153Asp) were found to be strongly associated with pseudoexfoliation. Two copies of the high risk haplotype at these single-nucleotide polymorphisms conferred a risk of 7.20 (95%CI: 3.04-20.75) compared with no copies of the high risk haplotype. Each of the disease-associated alleles is by far commoner in the normal population, and examination of cross-species homology reveals that the two disease-associated coding variants belong to the ancestral version of the gene. LOXL1 was found to be expressed by reverse transcription-polymerase chain reaction in all ocular tissues examined except retina. The presence of LOXL1 protein in ocular tissues of interest was demonstrated by western blotting. Specific bands of approximately 130 and 80 kDa, representing polymerized protein forms, were detected in the cornea, iris, ciliary body, lens capsule and optic nerve. The 42 kDa mature form of LOXL1 was detected in the iris and ciliary body. Our Caucasian population has a 9-fold lower lifetime incidence of pseudoexfoliation syndrome compared with Nordic populations despite having similar allelic architecture at the LOXL1 locus. This strongly suggests that as yet unidentified genetic or environmental factors independent of LOXL1 strongly influence the phenotypic expression of the syndrome.

Abnormal iris processes may be a marker of glaucoma gene carrier status in some cases of primary infantile glaucoma.

PURPOSE: To report the presence of dense and abnormal iris processes in the unaffected parents and sibling of a non consanguineous family where 3 children out of 4 suffer from primary infantile glaucoma (PIG). METHODS: A descriptive case report. All family members were clinically characterized. Candidate gene screening and chromosome analysis were also performed. RESULTS: The 3 children with PIG displayed a spectrum of anterior chamber angle anomalies with the absence of posterior embryotoxon and iridotrabeculodysgenesis abnormalities. Unaffected family members had dense and abnormal iris processes but no features of glaucoma. Candidate gene screening and chromosome analysis were normal. CONCLUSION: Iris processes indicate angle maldevelopment and may signify carrier status of an autosomal recessive glaucoma gene. Identification of iris processes in relatives of PIG children is a useful clinical sign that may be of benefit for genetic counseling and risk stratification purposes.

A novel deletion in the FTL gene causes hereditary hyperferritinemia cataract syndrome (HHCS) by alteration of the transcription start site.

Hereditary hyperferritinemia cataract syndrome (HHCS) is characterized by distinctive cataracts and high serum ferritin in the absence of iron overload. It is caused by mutations in the iron response element (IRE) of the Ferritin Light Chain (FTL) gene. Here we investigate the genetics of HHCS in a three generation Australian kindred with typical HHCS ocular lens morphology and high ferritin levels. Initial sequencing of the IRE failed to detect any mutations. Sequencing of the entire gene including the promoter region revealed a novel 25 bp deletion upstream of the IRE abolishing the transcription start site. In lymphoblastoid cells, the deletion allele was transcribed from an alternate start site within the lower stem of the IRE and mutation carriers had high cellular L-ferritin levels. This novel deletion in the promoter encompassing the transcription start site of the FTL gene is responsible for HHCS in this kindred. The initial primers for amplifying the IRE similar to those used by other researchers failed to detect this mutation. Therefore the genomic region assessed in HHCS cases for diagnosis should be expanded to include mutations of this type.

Myocilin Gly252Arg mutation and glaucoma of intermediate severity in Caucasian individuals.

OBJECTIVE: To determine the phenotype of an Australian pedigree with the myocilin (MYOC) Gly252Arg mutation, comparing it with other pedigrees carrying the same mutation. METHODS: All recruited subjects underwent a comprehensive clinical examination, including optic disc assessment, applanation tonometry, and visual field measurement. Mutation analysis was performed through direct sequencing. Haplotype analysis was performed using microsatellite markers around the MYOC gene. RESULTS: Eight Gly252Arg mutation carriers with glaucoma were identified from the same pedigree. Carriers' mean +/- SD age at diagnosis was 46.3 +/- 11.4 years (range, 31-60 years). Highest recorded intraocular pressure ranged from 27 to 42 mm Hg (mean +/- SD, 32.4 +/- 5.6 mm Hg). Cup-disc ratios in the worst eye ranged from 0.6 to 0.9. Six of the 8 individuals had undergone filtration surgery. A common founding haplotype between MY5 and D1S218 was found for Caucasian individuals tested with this mutation. One subject was compound heterozygotic for the MYOC Gly252Arg mutation and a novel MYOC Gly244Val variant. CONCLUSIONS: Although a common founder for Gly252Arg across Caucasian subjects was found, the phenotype from this Australian MYOC mutation-carrying pedigree is less severe than previously described. The severity of glaucoma caused by the Gly252Arg mutation may be similar to the Thr377Met MYOC mutation, yet is more severe than the most common Gln368Stop mutation. CLINICAL RELEVANCE: Since its implication in glaucoma, much work has been performed investigating the clinical features of MYOC-related glaucoma. Given the strong genotype-phenotype correlations with MYOC disease-causing variants, health care professionals armed with such molecular information are able to accurately counsel patients on their likely disease course. Our work suggests that the disease associated with MYOC Gly252Arg is less severe than previously described in other pedigrees with this specific mutation.

A Glaucoma Case-control Study of the WDR36 Gene D658G sequence variant.

PURPOSE: To investigate in Australian patients with glaucoma and normal controls the prevalence and associated phenotype of the WDR36 D658G mutation, which has previously been suggested to be a disease-causing mutation in pedigrees with primary open-angle glaucoma (POAG). DESIGN: Case-control study. METHODS: Two hundred forty-nine individuals with POAG and 217 age-matched control subjects were recruited through the Glaucoma Inheritance Study in Tasmania, Australia. Genomic DNA was amplified by polymerase chain reaction by intronic primers. The presence of the D658G variant was detected by BglI restriction enzyme digestion. RESULTS: The D658G variant was identified in four POAG cases (1.6%) and four control subjects (1.8%) (chi(2) = 0.04, P = .84). No control subject with the variant had a family history of glaucoma. CONCLUSIONS: The WDR36 D658G is a neutral variant in the Australian population. Further populations should be carefully assessed for this variant before concluding that WDR36 is a glaucoma gene.

A myocilin Gln368STOP homozygote does not exhibit a more severe glaucoma phenotype than heterozygous cases.

PURPOSE: To describe the phenotype of an individual homozygous for the common Gln368STOP myocilin mutation and to discuss the other family members. DESIGN: Cascade screening was performed for Australian families that had been identified as having the myocilin Gln368STOP mutation. METHODS: Recruited subjects underwent comprehensive clinical examination and mutation analysis for the Gln368STOP myocilin mutation by direct sequencing. RESULTS: One 49-year-old woman was found to be homozygous for the mutation. Her maximal recorded intraocular pressure was 17 mm Hg. Bilateral optic disk examination revealed small, healthy optic discs. Automated perimetry testing was normal. CONCLUSIONS: Neither the individual homozygous for the Gln368STOP myocilin mutation nor her younger heterozygous siblings displayed any signs suggestive of glaucoma. One of the two heterozygous parents did manifest glaucoma. Although there is the possibility of the homozygous individual developing glaucoma in the future, she does not manifest a phenotype that is more severe than usual.