Biomedical subjects

Susanne Kohl

Publications and source records attributed to Susanne Kohl.

3 recordsLinked to original sources

PubMed2026

Biallelic RDH11 variants cause syndromic retinitis pigmentosa with early-onset cataracts and neurodevelopmental delay: a multicenter case series.

Biallelic variants in the RDH11 gene, a retinol dehydrogenase involved in the visual cycle and systemic retinoid homeostasis, were initially implicated in a rare condition characterized by retinal dystrophy, early-onset cataract, neurodevelopmental anomalies and myopathy, through single-family reports, with this association more recently being confirmed in a larger study. Here, we further establish the pathogenic role of RDH11 by presenting a large multi-center cohort, comprising eight individuals from seven unrelated families. Comprehensive genetic analysis identified homozygous variants in all affected subjects, including two novel variants, strongly supporting loss-of-function as the primary disease mechanism. Detailed clinical phenotyping defined a consistent and severe multisystem disorder. Ophthalmologically, the hallmark features include bilateral congenital or early-childhood cataracts requiring surgical intervention, accompanied by retinitis pigmentosa (RP). In terms of extra-ocular involvement, the cohort exhibited a high prevalence of neurodevelopmental delay, including intellectual disability, autistic spectrum disorder and learning difficulties. These features were frequently accompanied by congenital microcephaly, intrauterine and postnatal growth restriction, facial dysmorphisms, and dental anomalies. By significantly expanding both the mutational and phenotypic spectrum of RDH11-related disease, our findings provide independent replication of this gene-disease association and definitively support RDH11 as a bona fide syndromic RP gene.

Journal Article↗

PubMed2026

Systematic functional evaluation of CNGA1 missense variants associated with retinitis pigmentosa.

BACKGROUND: Missense variants are frequently classified as variants of uncertain significance (VUS) according to the guidelines of the American College of Medical Genetics and Genomics and the Association of Molecular Pathology (ACMG/AMP). Consequently, disease relevance remains elusive, impeding molecular genetic diagnostics, patients` and family genetic counseling, and identification of patients eligible for clinical trials. Functional studies are critical for resolving the clinical significance of VUS. CNGA1 encodes the main subunit of the rod cyclic nucleotide-gated (CNG) channel, a vital component of the phototransduction cascade. Variants in CNGA1 are a rare cause of autosomal recessive retinitis pigmentosa and a phase I/II gene augmentation trial (NCT06291935) is currently ongoing highlighting the necessity to differentiate benign from pathogenic variants. METHODS: CNGA1 missense variants compiled from retinal disease patient cohorts, public databases and literature were functionally investigated using a medium-throughput aequorin-based assay and in vitro minigene splice assays for predicted exonic spliceogenic variants. Functional data were correlated with the in silico prediction of five variant effect predictors (VEPs) and applied to support or revise variants' ACMG/AMP classification. RESULTS: Data mining revealed 86 missense CNGA1 variants - including three novel - most of them lacking functional data; 65.1% of the variants were initially classified as VUS. The aequorin-based assay showed that 72.1% of tested variants significantly impaired CNG channel function and were classified as functionally abnormal, while 23.3% were functionally normal and 5% remained functionally uncertain. Correlation of the functional data with in silico predictions identified AlphaMissense and CPT-1 to be the most suitable tools for assessing CNGA1 missense variants. Using in vitro minigene splice assays, two putative missense variants were shown to induce missplicing. Based on the functional findings, 62.1% of the variants initially classified as VUS were re-categorized as likely pathogenic or likely benign. Furthermore, 93.3% of the variants initially classified as likely pathogenic showed an effect on CNGA1 channel function, confirming their disease relevance and supporting their reclassification as pathogenic. CONCLUSION: This study represents the first comprehensive functional assessment of disease-associated CNGA1 missense variants, thus significantly advancing the understanding of their disease relevance and improving molecular genetic diagnostics in patients.

Humans↗

PubMed2025

Bi-allelic loss-of-function variants in POC5 cause a syndromic retinal, endocrine, and neuromuscular ciliopathy.

PURPOSE: A homozygous loss-of-function (LoF) variant in POC5 was previously described in an individual with retinitis pigmentosa. We identified POC5 variants in 12 probands with a syndromic phenotype. We aim to define the phenotype spectrum and molecular mechanism associated with biallelic POC5 LoF variants. METHODS: We studied a cohort of 12 families with bi-allelic LoF POC5 variants and performed detailed phenotype analysis. POC5 localization studies were performed in 3 proband-derived fibroblast cell lines. RESULTS: Detailed phenotyping of probands with POC5 variants expands the phenotype spectrum beyond ocular manifestations. This syndrome causes not only rod-cone dystrophy but also diabetes mellitus with severe insulin resistance and partial lipodystrophy, kidney disease, and muscle cramps. The POC5 protein plays an essential role during cell cycle and cilium formation. Interestingly, POC5 localization studies in 3 proband-derived fibroblast cell lines show aberrant localization suggesting a ciliary defect. The phenotypes of the 12 families in this study fit well within the ciliopathy phenotype spectrum, except for lipodystrophy, which is not common in ciliopathies. CONCLUSION: We describe a multiorgan syndrome caused by bi-allelic LoF variants in POC5. This underscores the pleiotropic effects of POC5 variants and highlights the significance of adipose tissue and metabolic dysfunction in ciliopathies.

Humans↗