A novel mutation in GJA8 associated with autosomal dominant congenital cataract in a family of Indian origin

Purpose To identify the underlying genetic defect in a four-generation family of Chinese origin with autosomal dominant congenital cataract-microcornea syndrome (CCMC). Methods All individuals in the study underwent a full clinical examination and the details of history were collected . Genomic DNA extracted from peripheral blood was amplified by polymerase chain reaction (PCR) method and the exons of all candidate genes were sequenced. Results Direct sequencing of the encoding regions of the candidate genes revealed a heterozygous mutation c.592C→T in exon 2 of the gap junction protein, alpha 8 (GJA8) gene. This mutation was responsible for the familial disorder through the substitution of a highly conserved arginine to tryptophan at codon 198 (p.R198W). This change co-segregated with all affected members of the family, but was not detected either in the non-carrier relatives or in the 100 normal controls. Conclusions This report is the first to relate p.R198W mutation in GJA8 with CCMC. The result expands the mutation spectrum of GJA8 in associated with congenital cataract and microcornea, and implies that this gene has direct involvement with the development of the lens as well as the other anterior segment of the eye

A novel fan-shaped cataract-microcornea syndrome caused by a mutation of CRYAA in an Indian family

PURPOSE: The molecular characterization of an Indian family having 10 members in four generations affected with a unique fan-shaped cataract-microcornea syndrome. METHODS: Detailed family history and clinical data were recorded. A genome-wide screening by two-point linkage analysis using more than 400 microsatellite markers in combination with multipoint lod score and haplotype analysis was carried out. Mutation screening was performed in the candidate gene by bi-directional sequencing of amplified products. RESULTS: The cataract-microcornea locus in this family was mapped to a 23.5 cM region on chromosome 21q22.3. Direct sequencing of the candidate gene CRYAA revealed a heterozygous C>T transition resulting in the substitution of the highly conserved arginine at position 116 by cysteine (R116C). CONCLUSIONS: This study provides the report of mapping a locus for syndromal cataract (cataract-microcornea syndrome) on 21q22.3. The mutation observed in CRYAA in the present family highlights the phenotypic heterogeneity of the disorder in relation to the genotype, as an identical mutation has previously been reported in an American family with a different type of cataract. The "fan-shaped cataract" observed in the present family has not been reported before

Sutural cataract associated with a mutation in the ferritin light chain gene (FTL) in a family of Indian origin

PURPOSE: The molecular characterization of 27 members of an Indian family, with 13 members in four generations, affected with Y-sutural congenital cataract. METHODS: Detailed family history and clinical data were collected. A genome-wide scan by two-point linkage analysis using more than 400 microsatellite markers in combination with multipoint lod score and haplotype analysis was performed. Mutation screening was carried out in the candidate gene by bi-directional sequencing of amplified products. RESULTS: A maximum two-point lod score of 6.37 at theta=0.00 was obtained with marker D19S879. Haplotype analysis placed the cataract locus to a 5.0 cM region between D19S902 and D19S867, in close proximity to the L-ferritin light chain gene (FTL) on chromosome 19q13.3. Hematological tests in two affected individuals showed very high levels of serum ferritin without iron overload leading to the diagnosis of hyperferritinemia-cataract syndrome. Mutation screening in FTL identified a G>A change at position 32 (c.-168G>A) in a highly conserved 3 nucleotide motif that forms a loop structure in the iron responsive element (IRE) in the 5'-untranslated region (5'-UTR). This nucleotide alteration was neither seen in any unaffected member of the family nor found in 50 unrelated control subjects. CONCLUSIONS: The present study is the first report of a Y-sutural congenital cataract mapping to 19q13.3. The mutation observed in FTL in this family highlights the phenotypic heterogeneity of the disorder in relation to the genotype as the identical mutation (32 G>A) has previously been reported in two Italian families with entirely different phenotypes. It is also the first report of hereditary hyperferritinemia-cataract syndrome in a family of Indian origin

Quality of life and clinical characteristics of self-improving congenital ichthyosis within the disease spectrum of autosomal recessive congenital ichthyosis

Background Autosomal-recessive congenital ichthyosis (ARCI) is a heterogeneous group of ichthyoses presenting at birth. Self-improving congenital ichthyosis (SICI) is a subtype of ARCI and is diagnosed when skin condition improves remarkably (within years) after birth. So far, there are sparse data on SICI and quality of life (QoL) in this ARCI subtype. This study aims to further delineate the clinical spectrum of SICI as a rather unique subtype of ARCI. Objectives This prospective study included 78 patients (median age: 15 years) with ARCI who were subdivided in SICI (n = 18) and non-SICI patients (nSICI, n = 60) by their ARCI phenotype. Methods Quality of life (QoL) was assessed using the (Children's) Dermatology Life Quality Index. Statistical analysis was performed with chi-squared and t-Tests. Results The genetically confirmed SICI patients presented causative mutations in the following genes: ALOXE3 (8/16; 50.0%), ALOX12B (6/16; 37.5%), PNPLA1 (1/16; 6.3%) and CYP4F22 (1/16; 6.3%). Hypo-/anhidrosis and insufficient vitamin D levels (<30 ng/mL) were often seen in SICI patients. Brachydactyly (a shortening of the 4th and 5th fingers) was statistically more frequent in SICI (P = 0.023) than in nSICI patients. A kink of the ear's helix was seen in half of the SICI patients and tends to occur more frequently in patients with ALOX12B mutations (P = 0.005). QoL was less impaired in patients under the age of 16, regardless of ARCI type. Conclusions SICI is an underestimated, milder clinical variant of ARCI including distinct features such as brachydactyly and kinking of the ears. Clinical experts should be aware of these features when seeing neonates with a collodion membrane. SICI patients should be regularly checked for clinical parameters such as hypo-/anhidrosis or vitamin D levels and monitored for changes in quality of life

hiPSC-Derived Epidermal Keratinocytes from Ichthyosis Patients Show Altered Expression of Cornification Markers

Inherited ichthyoses represent a large heterogeneous group of skin disorders characterised by impaired epidermal barrier function and disturbed cornification. Current knowledge about disease mechanisms has been uncovered mainly through the use of mouse models or human skin organotypic models. However, most mouse lines suffer from severe epidermal barrier defects causing neonatal death and human keratinocytes have very limited proliferation ability in vitro. Therefore, the development of disease models based on patient derived human induced pluripotent stem cells (hiPSCs) is highly relevant. For this purpose, we have generated hiPSCs from patients with congenital ichthyosis, either non-syndromic autosomal recessive congenital ichthyosis (ARCI) or the ichthyosis syndrome trichothiodystrophy (TTD). hiPSCs were successfully differentiated into basal keratinocyte-like cells (hiPSC-bKs), with high expression of epidermal keratins. In the presence of higher calcium concentrations, terminal differentiation of hiPSC-bKs was induced and markers KRT1 and IVL expressed. TTD1 hiPSC-bKs showed reduced expression of FLG, SPRR2B and lipoxygenase genes. ARCI hiPSC-bKs showed more severe defects, with downregulation of several cornification genes. The application of hiPSC technology to TTD1 and ARCI demonstrates the successful generation of in vitro models mimicking the disease phenotypes, proving a valuable system both for further molecular investigations and drug development for ichthyosis patients

A Genome-wide Association Study of Dupuytren Disease Reveals 17 Additional Variants Implicated in Fibrosis

Individuals with Dupuytren disease (DD) are commonly seen by physicians and surgeons across multiple specialties. It is an increasingly common and disabling fibroproliferative disorder of the palmar fascia, which leads to flexion contractures of the digits, and is associated with other tissue-specific fibroses. DD affects between 5% and 25% of people of European descent and is the most common inherited disease of connective tissue. We undertook the largest GWAS to date in individuals with a surgically validated diagnosis of DD from the UK, with replication in British, Dutch, and German individuals. We validated association at all nine previously described signals and discovered 17 additional variants with p ≤ 5 × 10-8. As a proof of principle, we demonstrated correlation of the high-risk genotype at the statistically most strongly associated variant with decreased secretion of the soluble WNT-antagonist SFRP4, in surgical specimen-derived DD myofibroblasts. These results highlight important pathways involved in the pathogenesis of fibrosis, including WNT signaling, extracellular matrix modulation, and inflammation. In addition, many associated loci contain genes that were hitherto unrecognized as playing a role in fibrosis, opening up new avenues of research that may lead to novel treatments for DD and fibrosis more generally. DD represents an ideal human model disease for fibrosis research

Effective Immunological Guidance of Genetic Analyses Including Exome Sequencing in Patients Evaluated for Hemophagocytic Lymphohistiocytosis

We report our experience in using flow cytometry-based immunological screening prospectively as a decision tool for the use of genetic studies in the diagnostic approach to patients with hemophagocytic lymphohistiocytosis (HLH). We restricted genetic analysis largely to patients with abnormal immunological screening, but included whole exome sequencing (WES) for those with normal findings upon Sanger sequencing. Among 290 children with suspected HLH analyzed between 2010 and 2014 (including 17 affected, but asymptomatic siblings), 87/162 patients with "full" HLH and 79/111 patients with "incomplete/atypical" HLH had normal immunological screening results. In 10 patients, degranulation could not be tested. Among the 166 patients with normal screening, genetic analysis was not performed in 107 (all with uneventful follow-up), while 154 single gene tests by Sanger sequencing in the remaining 59 patients only identified a single atypical CHS patient. Flow cytometry correctly predicted all 29 patients with FHL-2, XLP1 or 2. Among 85 patients with defective NK degranulation (including 13 asymptomatic siblings), 70 were Sanger sequenced resulting in a genetic diagnosis in 55 (79%). Eight patients underwent WES, revealing mutations in two known and one unknown cytotoxicity genes and one metabolic disease. FHL3 was the most frequent genetic diagnosis. Immunological screening provided an excellent decision tool for the need and depth of genetic analysis of HLH patients and provided functionally relevant information for rapid patient classification, contributing to a significant reduction in the time from diagnosis to transplantation in recent years

The genetic basis of Dupuytren's disease

Dupuytren’s disease is a multifactorial disorder. Twin studies and familial studies have demonstrated a strong genetic component for Dupuytren’s disease. An autosomal dominant mode of inheritance with reduced penetrance has been suggested; however, a gene involved in Dupuytren’s disease using a family-based gene mapping approach has not been identified so far. Therefore we have embarked on a genome-wide association study to identify susceptibility genes for Dupuytren’s disease. Here we give a brief introduction into molecular studies of multifactorial disorders and describe basic approaches used in these studies. Based on recent findings concerning the genetics of Dupuytren’s disease, we explain the rationale for our approach and the conclusions that could be expected from the work. Additionally, this chapter may serve as a brief introduction into the genetic studies in Dupuytren’s disease