Richard Ad Mills

Genome-wide association study identifies susceptibility loci for open angle glaucoma at TMCO1 and CDKN2B-AS1

We report a genome-wide association study for open-angle glaucoma (OAG) blindness using a discovery cohort of 590 individuals with severe visual field loss (cases) and 3,956 controls. We identified associated loci at TMCO1 (rs4656461[G] odds ratio (OR) = 1.68, P = 6.1 × 10−10) and CDKN2B-AS1 (rs4977756[A] OR = 1.50, P = 4.7 × 10−9). We replicated these associations in an independent cohort of cases with advanced OAG (rs4656461 P = 0.010; rs4977756 P = 0.042) and two additional cohorts of less severe OAG (rs4656461 combined discovery and replication P = 6.00 × 10−14, OR = 1.51, 95% CI 1.35–1.68; rs4977756 combined P = 1.35 × 10−14, OR = 1.39, 95% CI 1.28–1.51). We show retinal expression of genes at both loci in human ocular tissues. We also show that CDKN2A and CDKN2B are upregulated in the retina of a rat model of glaucoma.

Apparent autosomal dominant keratoconus in a large Australian pedigree accounted for by digenic inheritance of two novel loci

Keratoconus is a debilitating ocular disease characterised by progressive asymmetrical thinning of the cornea, the clear covering at the front of the eye. The resulting protrusion of the cornea results in severe refractive error, in the most severe cases requiring corneal grafting. It is a complex disease with a genetic component. Despite several reports of linked loci, major gene identification has been elusive. A genome-wide linkage scan in a large Australian pedigree with apparent autosomal dominant keratoconus was conducted using the Affymetrix 10K SNP chip and two regions of linkage identified. Functional candidate genes from within both linkage peaks were assessed for corneal expression and screened for mutations in affected family members. Equal evidence of linkage was detected to both 1p36.23-36.21 and 8q13.1-q21.11 with LOD scores of 1.9. Analysis of both loci concurrently suggests digenic linkage with two-locus LOD score of 3.4. All affected individuals carry identical haplotypes at both loci. Carriers of either linked haplotype without the other do not have keratoconus. No mutations were identified in the following candidate genes expressed in the cornea: ENO1, CTNNBIP1, PLOD1, UBIAD1, SPSB1 or TCEB1. Although the pedigree appears to demonstrate simple autosomal dominant inheritance, the disorder is actually genetically complex. This pedigree may provide a link between inherited forms of keratoconus and sporadic cases.

Heritability of central corneal thickness in nuclear families.

PURPOSEnMany 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.nnnMETHODSnIndex 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.nnnRESULTSnThirty-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).nnnCONCLUSIONSnThese results indicate that CCT shows strong parent-child heritability, with offspring likely to demonstrate CCT similar to the parental index case.

Mutational Analysis of MIR184 in Sporadic Keratoconus and Myopia

PURPOSEnA mutation miR-184(+57C>T) in the seed region of miR-184 (encoded by MIR184 [MIM*613146]) results in familial severe keratoconus combined with early-onset anterior polar cataract and endothelial dystrophy, iris hypoplasia, congenital cataract, and stromal thinning (EDICT) syndrome (MIM#614303). In order to investigate the phenotypic spectrum resulting from MIR184 mutation, MIR184 was sequenced in a keratoconus cohort of mixed ethnicity and a Chinese axial myopia cohort.nnnMETHODSnSequencing of MIR184 was performed in 780 unrelated keratoconus patients and 96 unrelated Han southern Chinese subjects with axial myopia. Effects of identified mutations on RNA secondary structure were predicted computationally using mFold and RNAFold algorithms. MIR184 amplicons from patients harboring mutations were cloned and transfected into human embryonic kidney 293T (HEK293T) cells, and mature mutant miR-184 expression was analyzed by stem-loop real-time quantitative PCR (RT-qPCR).nnnRESULTSnTwo novel heterozygous substitution mutations in MIR184 were identified in the two patients with isolated keratoconus: miR-184(+8C>A) and miR-184(+3A>G). Computational modeling predicted that these mutations would alter the miR-184 stem-loop stability and secondary structure. Ex vivo miR-184 expression analysis demonstrated that miR-184(+8C>A) almost completely repressed the expression of miR-184 (P = 0.022), and miR-184(+3A>G) reduced the expression of miR-184 by approximately 40% (P = 0.002). There was no significant association of rs41280052, which lies within the stem-loop of miR-184, with keratoconus. No MIR184 mutations were detected in the axial myopia cohort.nnnCONCLUSIONSnTwo novel heterozygous substitution mutations in MIR184 were identified in two patients with isolated keratoconus: miR-184(+8C>A) and miR-184(+3A>G). Mutations in MIR184 are a rare cause of keratoconus and were found in 2 of 780 (0.25%) cases.

Pythium insidiosum keratitis in an Australian child

A 3‐year‐old girl from the Northern Territory developed suppurative keratitis after swimming in pools. A mycelial organism suspected to be Pythium insidiosum was cultured. Treatment with polyhexamethylene biguanide and voriconazole for 5u2003days was unsuccessful, and a corneal graft was performed. The infection was cleared and when last seen 14u2003months after surgery the patient had a stable graft and useful vision. The identification of the organism was confirmed by rRNA gene sequencing. P. insidiosum is an oomycete, an organism more closely related to kelp than to fungi. Masses of hyphae were seen in sections and, for the first time, the ultrastructure of P. insidiosum in human tissue is described. The staining characteristics of cultured hyphae were assessed; lactofuchsin and acridine orange were found to be the most useful methods. Although the diagnosis of P. insidiosum keratitis is not difficult, and the organism is susceptible in vitro to a number of antimicrobial agents, early corneal transplantation remains the treatment of choice.

Elevation of serum asymmetrical and symmetrical dimethylarginine in patients with advanced glaucoma.

PURPOSEnAsymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) are the dimethylated isomeric derivatives of the amino acid L-arginine. ADMA is an endogenous inhibitor of nitric oxide synthase (NOS), while SDMA is a competitive inhibitor of cellular uptake of L-arginine, the substrate for NOS. As such, these metabolites are associated with endothelial dysfunction. As the nitric oxide pathway and endothelial dysfunction have been implicated in glaucoma, the aim of this study was to investigate serum ADMA, SDMA, and L-arginine levels in individuals with advanced glaucoma compared with normal controls. In addition, we have investigated genetic variation in the DDAH1 and DDAH2 genes, encoding the enzymes responsible for degradation of ADMA, for association with ADMA level in glaucoma patients and controls.nnnMETHODSnTwo hundred eleven patients with advanced glaucoma and 295 normal controls were recruited. Liquid chromatography-tandem mass spectrometry was used to measure the serum ADMA, SDMA, and L-arginine levels of participants. Single nucleotide polymorphisms in the DDAH1 and DDAH2 genes reportedly associated with ADMA level were genotyped in all individuals.nnnRESULTSnA significant increase in both serum ADMA and SDMA concentration was detected in advanced glaucoma cases compared with controls (P ≤ 0.0001). No significant change was detected in serum L-arginine concentration. No association of polymorphisms in DDAH1 and DDAH2 with either ADMA level or glaucoma was detected.nnnCONCLUSIONSnThe serum levels of two dimethylarginines, ADMA and SDMA, are associated with advanced glaucoma. These data further implicate the nitric-oxide pathway in glaucoma pathogenesis.

Erosive mucosal lichen planus and secondary epiphora responding to systemic cyclosporin A treatment.

Erosive mucosal lichen planus (LP) is a well‐established variant of LP characterized by the formation of ulcerative lesions predominantly involving the oral and genital mucosae. Less commonly, this condition may involve oesophageal and/or ocular mucosal surfaces, and case reports within the ophthalmology literature have recently confirmed the potential for this condition to affect the nasolacrimal ducts. We report the case of a woman with severe cicatrizing mucosal LP and ocular symptoms secondary to presumed nasolacrimal duct involvement. We also report the potential for this newly appreciated manifestation of LP to respond to systemic cyclosporin A.

Misdiagnosis of orthokeratology‐related Acanthamoeba keratitis as herpes simplex virus keratitis

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Sensitivity of confocal laser tomography versus optical coherence tomography in detecting advanced glaucoma

Purpose:u2002 To determine the sensitivity of manufacturer supported normative algorithms in Heidelberg retinal tomography (HRT) and Stratus optical coherence tomography (OCT) in detecting advanced primary open angle glaucoma.

Severe intraocular pressure response to periocular or intravitreal steroid treatment in Australia and New Zealand: data from the Australian and New Zealand Ophthalmic Surveillance Unit

Increase in intraocular pressure is a recognized complication of corticosteroid treatment via intravitreal or periocular injections for treatment of a range of conditions including macular oedema and retinal neovascularization.