This November’s published articles citing Golden Helix software serve as a testament to our broad application and utility in NGS data analysis. We are always proud of our customers and the contributions they make to scientific discovery. Their continued work and research are motivators for us to continue delivering the best products we can. This month we are featuring two publications that mention VarSeq and another featuring GenomeBrowse. As always, we encourage you to go and read the complete publication!

Mono- and biallelic germline variants of DNA glycosylase genes in colon adenomatous polyposis families from two continents

Recently, biallelic germline variants of the DNA glycosylase genes MUTYH and NTHL1 were linked to polyposis susceptibility. Significant fractions remain without a molecular explanation, warranting searches for underlying causes. We used exome sequencing to investigate clinically well-defined adenomatous polyposis cases and families from Finland (N=34), Chile (N=21), and Argentina (N=12), all with known susceptibility genes excluded. Nine index cases (13%) revealed germline variants with proven or possible pathogenicity in the DNA glycosylase genes, involving NEIL1 (mono- or biallelic) in 3 cases, MUTYH (monoallelic) in 3 cases, NTHL1 (biallelic) in 1 case, and OGG1 (monoallelic) in 2 cases. NTHL1 was affected with the well-established, pathogenic c.268C>T, p.(Gln90Ter) variant. A recurrent heterozygous NEIL1 c.506G>A, p.(Gly169Asp) variant was observed in two families. In a Finnish family, the variant occurred in trans with a truncating NEIL1 variant (c.821delT). In an Argentine family, the variant co-occurred with a genomic deletion of exons 2 – 11 of PMS2. Mutational signatures in tumor tissues complied with biological functions reported for NEIL1. Our results suggest that germline variants in DNA glycosylase genes may occur in a non-negligible proportion of unexplained colon polyposis cases and may predispose to tumor development.

Olkinuora AP, Mayordomo AC, Kauppinen AK, Cerliani MB, Coraglio M, Collia ÁK, Gutiérrez A, Alvarez K, Cassana A, Lopéz-Köstner F, Jauk F, García-Rivello H, Ristimäki A, Koskenvuo L, Lepistö A, Nieminen TT, Vaccaro CA, Pavicic WH and Peltomäki P (2022) Mono- and biallelic germline variants of DNA glycosylase genes in colon adenomatous polyposis families from two continents. Front. Oncol. 12:870863. https://doi.org/10.3389/fonc.2022.870863

A Novel GCK Large Genomic Rearrangement in a Patient with MODY-2 Detected by Clinical Exome Sequencing

Maturity-onset diabetes of the young (MODY) is a rare form of non-autoimmune diabetes with an autosomal dominant inheritance. To date, 14 genes have been reported as genetic basis of MODY. GCK gene, encoding the glucokinase enzyme, was the first MODY gene to be identified. GCK heterozygous inactivating variants cause the GCK-MODY or MODY2 subtype. However, partial or whole gene deletions have been rarely identified, showing it to be a rare cause of GCK-MODY. We reported the molecular evaluation of a Ukrainian patient with clinical diagnosis of MODY2. We performed the Next generation sequencing of the clinical exome using the Clinical Exome Solution^® kit (SOPHiA Genetics), followed by the design of a 14 genes virtual panel related to the suggestive diagnosis of MODY. Bioinformatics analysis was performed using the SOPHiA DDM platform (SOPHiA Genetics). The SALSA MLPA kit for MODY (MRC-Holland) was used for relative quantification of GCK exons. From the molecular evaluation, no pathogenic sequence variants were detected in the investigated genes. Copy Number Variation analysis was able to identify a large deletion involving the last three exons of the GCK gene. This result was confirmed by MLPA. To the best of our knowledge, the identified rearrangement has never been reported in the literature.

Concolino, P.; Tartaglione, L.; De Paolis, E.; Carrozza, C.; Urbani, A.; Minucci, A.; Pitocco, D.; Santonocito, C. A Novel GCK Large Genomic Rearrangement in a Patient with MODY-2 Detected by Clinical Exome Sequencing. Genes 2022, 13, 2104. https://doi.org/10.3390/genes13112104

Congenital Nail Disorders among Children with Suspected Ectodermal Dysplasias

We report on a cohort of 204 children referred between January 2017 and January 2022 to the German Center for Ectodermal Dysplasias, Erlangen. The most frequent reasons for referral were tooth malformations and lack of multiple teeth leading to the suspicion of an ectodermal dysplasia. Many patients also suffered from being unable to perspire. Nail abnormalities, in contrast, represented a much rarer finding, albeit the impact on some individuals was large. As ectodermal dysplasias are congenital genetic conditions affecting the development and/or homeostasis of two or more ectodermal derivatives, including hair, teeth, nails, and certain glands, we analyzed congenital nail disorders detected in these patients. Dystrophic or otherwise abnormal nails were evident in 17 of 18 subjects with pathogenic WNT10A or GJB6 variants but in none of 161 children with EDA variants underlying X-linked hypohidrotic ectodermal dysplasia. However, 2 of 17 children who carry mutations in EDAR or EDARADD, two other genes involved in the ectodysplasin A signaling pathway, showed nail abnormalities, such as brittle or hypoplastic nails. TP63 variants were regularly associated with nail disorders. In one girl, anonychia congenita caused by a compound heterozygous variant of the R-spondin-4 gene (RSPO4) was diagnosed. Thus, nail dysplasia is rarer among patients with ectodermal dysplasia than commonly thought.

Maier-Wohlfart, S.; Aicher, C.; Willershausen, I.; Peschel, N.; Meißner, U.; Gölz, L.; Schneider, H. Congenital Nail Disorders among Children with Suspected Ectodermal Dysplasias. Genes 2022, 13, 2119. https://doi.org/10.3390/genes13112119