Genetics of anophthalmia and microphthalmia. Part 1, Non-syndromic anophthalmia/microphthalmia

Eye formation is the result of coordinated induction and differentiation processes during embryogenesis. Disruption of any one of these events has the potential to cause ocular growth and structural defects, such as anophthalmia and microphthalmia (A/M). A/M can be isolated or occur with systemic anomalies, when they may form part of a recognizable syndrome. Their etiology includes genetic and environmental factors; several hundred genes involved in ocular development have been identified in humans or animal models. In humans, around 30 genes have been repeatedly implicated in A/M families, although many other genes have been described in single cases or families, and some genetic syndromes include eye anomalies occasionally as part of a wider phenotype. As a result of this broad genetic heterogeneity, with one or two notable exceptions, each gene explains only a small percentage of cases. Given the overlapping phenotypes, these genes can be most efficiently tested on panels or by whole exome/genome sequencing for the purposes of molecular diagnosis. However, despite whole exome/genome testing more than half of patients currently remain without a molecular diagnosis. The proportion of undiagnosed cases is even higher in those individuals with unilateral or milder phenotypes. Furthermore, even when a strong gene candidate is available for a patient, issues of incomplete penetrance and germinal mosaicism make diagnosis and genetic counselling challenging. In this review, we present the main genes implicated in nonsyndromic human A/M phenotypes and, for practical purposes, classify them according to the most frequent or predominant phenotype each is associated with. Our intention is that this will allow clinicians to rank and prioritize their molecular analyses and interpretations according to the phenotypes of their patients

Pediatric cataract, myopic astigmatism, familial exudative vitreoretinopathy and primary open-angle glaucoma co-segregating in a family

Purpose: To describe an Australian pedigree of European descent with a variable autosomal dominant phenotype of: pediatric cortical cataract (CC), asymmetric myopia with astigmatism, familial exudative vitreoretinopathy (FEVR), and primary open-angle glaucoma (POAG). Methods: Probands with CC, FEVR, and POAG were enrolled in three independent genetic eye studies in Tasmania. Genealogy confirmed these individuals were closely related and subsequent examination revealed 11 other family members with some or all of the associated disorders. Results: Twelve individuals had CC thought to be of childhood onset, with one child demonstrating progressive lenticular opacification. One individual had severe retinal detachment while five others had dragged retinal vessels. Seven individuals had POAG. Seven individuals had myopia in at least one eye ≤-3 Diopters. DNA testing excluded mutations in myocilin, trabecular meshwork inducible glucocorticoid response (MYOC) and tetraspanin 12 (TSPAN12). Haplotype analysis excluded frizzled family receptor 4 (FZD4) and low density lipoprotein receptor-related protein 5 (LRP5), but only partly excluded EVR3. Multipoint linkage analysis revealed multiple chromosomal single-nucleotide polymorphisms (SNPs) of interest, but no statistically significant focal localization. Conclusions: This unusual clustering of ophthalmic diseases suggests a possible single genetic cause for an apparently new cataract syndrome. This family’s clinical ocular features may reflect the interplay between retinal disease with lenticular changes and axial length in the development of myopia and glaucoma

FOXE3 mutations: genotype-phenotype correlations

Microphthalmia and anophthalmia (MA) are severe developmental eye anomalies, many of which are likely to have an underlying genetic cause. More than 30 genes have been described, each of which is responsible for a small percentage of these anomalies. Amongst these, is the FOXE3 gene, which was initially described in individuals with dominantly inherited anterior segment dysgenesis and, subsequently, associated with recessively inherited primary aphakia, sclerocornea and microphthalmia. In this work, we describe 8 individuals presenting with a MA phenotype. Among them, 7 are carrying biallelic recessive FOXE3 mutations and 2 of these have novel mutations: p.(Ala78Thr) and p.(Arg104Cys). The last of our patients is carrying in the heterozygous state the recessive p.(Arg90Leu) mutation in the FOXE3 gene. To further understand FOXE3 involvement in this wide spectrum of ocular anomalies with two different patterns of inheritance, we reviewed all individuals with ocular abnormalities described in the literature for which a FOXE3 mutation was identified. This review demonstrates that correlations exist between the mutation type, mode of inheritance and the phenotype severity. Furthermore, understanding the genetic basis of these conditions will contribute to overall understanding of eye development, improve the quality of care, genetic counseling and, in future, gene based therapies

Confirmation of TENM3 Involvement in Autosomal Recessive Colobomatous Microphthalmia

Anophthalmia and microphthalmia are the most severe malformations of the eye, referring to a congenital absence, and a reduced size of the eyeball respectively. More than 20 genes have been shown to be mutated in patients with syndromic and non-syndromic forms of anophthalmia–microphthalmia. In a recent study combining autozygome and exome analysis, a homozygous loss of function mutation in TENM3 (previously named ODZ3) was reported in two siblings with isolated bilateral colobomatous microphthalmia from a consanguineous Saudi family. Herein, we report a third patient (not related to the previously reported family) with bilateral colobomatous microphthalmia and developmental delay in whom genetic studies identified a homozygous TENM3 splicing mutation c.2968-2A>T (p.Val990Cysfs*13). This report supports the association of TENM3 mutations with colobomatous microphthalmia and expands the phenotypic spectrum associated with mutations in this gene

Exploring venlafaxine pharmacokinetic variability with a phenotyping approach, a multicentric french-swiss study (MARVEL study).

It is well known that the standard doses of a given drug may not have equivalent effects in all patients. To date, the management of depression remains mainly empirical and often poorly evaluated. The development of a personalized medicine in psychiatry may reduce treatment failure, intolerance or resistance, and hence the burden and costs of mood depressive disorders. The Geneva Cocktail Phenotypic approach presents several advantages including the "in vivo" measure of different cytochromes and transporter P-gp activities, their simultaneous determination in a single test, avoiding the influence of variability over time on phenotyping results, the administration of low dose substrates, a limited sampling strategy with an analytical method developed on DBS analysis. The goal of this project is to explore the relationship between the activity of drug-metabolizing enzymes (DME), assessed by a phenotypic approach, and the concentrations of Venlafaxine (VLX) + O-demethyl-venlafaxine (ODV), the efficacy and tolerance of VLX. This study is a multicentre prospective non-randomized open trial. Eligible patients present a major depressive episode, MADRS over or equal to 20, treatment with VLX regardless of the dose during at least 4 weeks. The Phenotype Visit includes VLX and ODV concentration measurement. Following the oral absorption of low doses of omeprazole, midazolam, dextromethorphan, and fexofenadine, drug metabolizing enzymes activity is assessed by specific metabolite/probe concentration ratios from a sample taken 2 h after cocktail administration for CYP2C19, CYP3A4, CYP2D6; and by the determination of the limited area under the curve from the capillary blood samples taken 2-3 and 6 h after cocktail administration for CYP2C19 and P-gp. Two follow-up visits will take place between 25 and 40 days and 50-70 days after inclusion. They include assessment of efficacy, tolerance and observance. Eleven french centres are involved in recruitment, expected to be completed within approximately 2 years with 205 patients. Metabolic ratios are determined in Geneva, Switzerland. By showing an association between drug metabolism and VLX concentrations, efficacy and tolerance, there is a hope that testing drug metabolism pathways with a phenotypical approach would help physicians in selecting and dosing antidepressants. The MARVEL study will provide an important contribution to increasing the knowledge of VLX variability and in optimizing the use of methods of personalized therapy in psychiatric settings. ClinicalTrials.gov NCT02590185 (10/27/2015). This study is currently recruiting participants

Relative frequencies of inherited retinal dystrophies and optic neuropathies in Southern France: assessment of 21-year data management

PURPOSE: Inherited retinal dystrophies (IRDs) and inherited optic neuropathies (IONs) are rare diseases defined by specific clinical and molecular features. The relative prevalence of these conditions was determined in Southern France. METHODS: Patients recruited from a specialized outpatient clinic over a 21-year period underwent extensive clinical investigations and 107 genes were screened by polymerase chain reaction/sequencing. RESULTS: There were 1957 IRD cases (1481 families) distributed in 70% of pigmentary retinopathy cases (56% non-syndromic, 14% syndromic), 20% maculopathies and 7% stationary conditions. Patients with retinitis pigmentosa were the most frequent (47%) followed by Usher syndrome (10.8%). Among non-syndromic pigmentary retinopathy patients, 84% had rod-cone dystrophy, 8% cone-rod dystrophy and 5% Leber congenital amaurosis. Macular dystrophies were encountered in 398 cases (30% had Stargardt disease and 11% had Best disease). There were 184 ION cases (127 families) distributed in 51% with dominant optic neuropathies, 33% with recessive/sporadic forms and 16% with Leber hereditary optic neuropathy. Positive molecular results were obtained in 417/609 families with IRDs (68.5%) and in 27/58 with IONs (46.5%). The sequencing of 5 genes (ABCA4, USH2A, MYO7A, RPGR and PRPH2) provided a positive molecular result in 48% of 417 families with IRDs. Except for autosomal retinitis pigmentosa, in which less than half the families had positive molecular results, about 75% of families with other forms of retinal conditions had a positive molecular diagnosis. CONCLUSIONS: Although gene discovery considerably improved molecular diagnosis in many subgroups of IRDs and IONs, retinitis pigmentosa, accounting for almost half of IRDs, remains only partly molecularly defined

Arch Neurol

BACKGROUND: Friedreich ataxia (FA) is the most frequent type of autosomal recessive cerebellar ataxia, occurring at a mean age of 16 years. Nearly 98% of patients with FA present with homozygous GAA expansions in the FXN gene. The remaining patients are compound heterozygous for an expansion and a point mutation. Patients who are compound heterozygous for an exonic deletion and an expansion are exquisitely rare. OBJECTIVES: To describe 6 patients affected with FA due to an exonic deletion mutation (FAexdel) and to compare these 6 patients with FAexdel with 46 patients consecutively diagnosed with typical FA due to homozygous GAA expansion and whose small expansions were within the same range as that of the expansions of the patients with FAexdel. DESIGN: Description of a series. SETTING: Academic research. PATIENTS: Six patients with FAexdel and 46 patients with typical FA. INTERVENTION: FXN gene analysis, including assessments of GAA expansion and exon sequencing and determination of exonic copy numbers using multiplex ligation-dependent probe amplification. RESULTS: We identified 6 patients with FA who presented with the combination of 1 GAA expansion and 1 FXN exonic deletion. The mean (SD) age at onset of the disease was earlier for patients with FAexdel (7 [4] years [range, 3-12 years]) than for patients with typical FA (15 [5] years [range, 6-30 years]) (P = .001), and the median time to confinement to wheelchair was shorter for patients with FAexdel (20 years) than for patients with typical FA (28 years) (P = .002). There was no difference between the mean (SD) size of the expansion for the patients with FAexdel (780 [256] GAA triplet repeat sequences [range, 340-1070 GAA triplet repeat sequences]) and the mean (SD) size of the short expansion for the patients with typical FA (634 [163] GAA triplet repeat sequences [range, 367-1000 GAA triplet repeat sequences]) (P = .10). The mean disease duration before becoming wheelchair bound was shorter for patients with FAexdel (9 years) than for patients with typical FA (13 years), and the incidence of cardiomyopathy was higher for patients with FAexdel (84%) than for patients with typical FA (68%). However, these differences were not significant, probably owing to the small size of the FAexdel group. The other extraneurological signs, such as scoliosis or diabetes mellitus, were particularly frequently observed in the FAexdel group. One patient presented at 9 years of age with severe angina and marked cardiomyopathy that confined her to a wheelchair. Three patients had disabling autonomic disturbances. It appears that exonic deletion significantly contributes to the clinical picture of patients with FA. CONCLUSIONS: Friedreich ataxia due to an exonic deletion mutation corresponds to an early onset and severe variant of FA. FXN should be investigated for exonic deletion in patients with early-onset FA in which only 1 GAA expansion without a point mutation is found. Patients with FAexdel have to be carefully observed using cardiological, orthopaedic, endocrinological, gastroenterological, and ophthalmological data. Friedreich ataxia due to an exonic deletion mutation should be suspected in young patients presenting with severe scoliosis

A randomized, double-blind, placebo-controlled trial evaluating cysteamine in Huntington's disease

BACKGROUND: Cysteamine has been demonstrated as potentially effective in numerous animal models of Huntington\u27s disease. METHODS: Ninety-six patients with early-stage Huntington\u27s disease were randomized to 1200 mg delayed-release cysteamine bitartrate or placebo daily for 18 months. The primary end point was the change from baseline in the UHDRS Total Motor Score. A linear mixed-effects model for repeated measures was used to assess treatment effect, expressed as the least-squares mean difference of cysteamine minus placebo, with negative values indicating less deterioration relative to placebo. RESULTS: At 18 months, the treatment effect was not statistically significant - least-squares mean difference, -1.5 ± 1.71 (P = 0.385) - although this did represent less mean deterioration from baseline for the treated group relative to placebo. Treatment with cysteamine was safe and well tolerated. CONCLUSIONS: Efficacy of cysteamine was not demonstrated in this study population of patients with Huntington\u27s disease. Post hoc analyses indicate the need for definitive future studies. © 2017 International Parkinson and Movement Disorder Society