Genetic Analysis in a Swiss Cohort of Bilateral Congenital Cataract

Importance Identification of geographic population-based differences in genotype and phenotype heterogeneity are important for targeted and patient-specific diagnosis and treatment, counseling, and screening strategies. Objective To report disease-causing variants and their detailed phenotype in patients with bilateral congenital cataract from a single center in Switzerland and thereby draw a genetic map and perform a genotype-phenotype comparison of this cohort. Design, Setting, and Participants This clinical and molecular-genetic cohort study took place through the collaboration of the Department of Ophthalmology at the University Hospital Zurich and the Institute of Medical Molecular Genetics, University of Zurich, Schlieren, Switzerland. Thirty-seven patients from 25 families with different types of bilateral congenital cataract were included. All participating family members received a comprehensive eye examination. Whole exome sequencing was performed in the index patients, followed by a filtering process to detect possible disease-associated variants in genes previously described in association with congenital cataract. Probable disease-causing variants were confirmed by Sanger sequencing in available family members. All data were collected from January 2018 to June 2020, and the molecular-genetic analyses were performed from January 2019 to July 2020. Main Outcomes and Measures Identification of the underlying genetic causes of bilateral congenital cataract, including novel disease-causing variants and phenotype correlation. Results Among the 37 patients (18 [49%] male and 19 [51%] female; mean [SD] age, 17.3 [15.9] years) from 25 families, pathogenic variants were detected in 20 families (80% detection rate), which included 13 novel variants in the following genes: BCOR, COL4A1, CRYBA2, CRYBB2, CRYGC, CRYGS, GJA3, MAF, NHS, and WFS1. Putative disease-causing variants were identified in 14 of 20 families (70%) as isolated cases and in 6 of 20 families (30%) with syndromic cases. A recessive variant in the CRYBB2 gene in a consanguineous family with 2 affected siblings showing a nuclear and sutural cataract was reported in contrast to previously published reports. In addition, the effect on splicing in a minigene assay of a novel splice site variant in the NHS gene (c.[719-2A>G]) supported the pathogenicity of this variant. Conclusions and Relevance This study emphasizes the importance of genetic testing of congenital cataracts. Known dominant genes need to be considered for recessive inheritance patterns. Syndromic types of cataract may be underdiagnosed in patients with mild systemic features

Neutrophils in Cystic Fibrosis Display a Distinct Gene Expression Pattern

We compared gene expression in blood neutrophils (polymorphonuclear leukocytes, or PMNs) collected from healthy subjects with those of cystic fibrosis (CF) patients devoid of bacterial colonization. Macroarray analysis of 1050 genes revealed upregulation of 62 genes and downregulation expression of 27 genes in CF blood PMNs. Among upregulated genes were those coding for vitronectin, some chemokines (particularly CCL17 and CCL18), some interleukin (IL) receptors (IL-3, IL-8, IL-10, IL-12), all three colony-stimulating factors (G-, M-, GM-CSF), numerous genes coding for molecules involved in signal transduction, and a few genes under the control of γ-interferon. In contrast, none of the genes coding for adhesion molecules were modulated. The upregulation of six genes in CF PMNs (coding for thrombospondin-1, G-CSF, CXCL10, CCL17, IKKɛ, IL-10Ra) was further confirmed by qPCR. In addition, the increased presence of G-CSF, CCL17, and CXCL10 was confirmed by ELISA in supernatants of neutrophils from CF patients. When comparison was performed between blood and airway PMNs of CF patients, there was a limited difference in terms of gene expression. Only the mRNA expression of amphiregulin and tumor necrosis factor (TNF) receptor p55 were significantly higher in airway PMNs. The presence of amphiregulin was confirmed by ELISA in the sputum of CF patients, suggesting for the first time a role of amphiregulin in cystic fibrosis. Altogether, this study clearly demonstrates that blood PMNs from CF patients display a profound modification of gene expression profile associated with the disease, suggesting a state of activation of these cells