Statistical Dissection of the Genetic Determinants of Phenotypic Heterogeneity in Genes with Multiple Associated Rare Diseases.

Phenotypicheterogeneity is a phenomenon in which distinct phenotypes can develop in individuals bearing pathogenic variants in the same gene. Genetic factors, gene interactions, and environmental factors are usually considered the key mechanisms of this phenomenon. Phenotypic heterogeneity may impact the prognosis of the disease severity and symptoms. In our work, we used publicly available data on the association between genetic variants and Mendelian disease to investigate the genetic factors (such as the intragenic localization and type of a variant) driving the heterogeneity of gene-disease relationships. First, we showed that genes linked to multiple rare diseases (GMDs) are more constrained and tend to encode more transcripts with high levels of expression across tissues. Next, we assessed the role of variant localization and variant types in specifying the exact phenotype for GMD variants. We discovered that none of these factors is sufficient to explain the phenomenon of such heterogeneous gene-disease relationships. In total, we identified only 38 genes with a weak trend towards significant differences in variant localization and 30 genes with nominal significant differences in variant type for the two associated disorders. Remarkably, four of these genes showed significant differences in both tests. At the same time, our analysis suggests that variant localization and type are more important for genes linked to autosomal dominant disease. Taken together, our results emphasize the gene-level factors dissecting distinct Mendelian diseases linked to one common gene based on open-access genetic data and highlight the importance of exploring other factors that contributed to phenotypic heterogeneity.

Human exome sequence data in support of somatic mosaicism in carotid atherosclerosis.

Understanding the mechanisms underlying the connection between somatic mosaicism and cardiovascular disease is likely essential for the future of personalized medicine. This article is aimed at providing data on somatic mosaicism in human carotid atherosclerosis. An advanced carotid atherosclerotic plaque and white blood cells were collected simultaneously from each patient (eight Slavic males, aged 67 ± 3.8 years [mean ± SD]) to assess the spectrum of germline and somatic genetic variants. Exome sequencing of DNA from the samples was performed with the SureSelect Clinical Research Exome Enrichment Kit (Agilent Technologies) and HiSeq 1500 (Illumina). The dataset contains germline and somatic single-nucleotide variants and small indels identified in the advanced carotid atherosclerotic plaque and white blood cells of each patient. This dataset does not include copy number variants owing to a lack of suitable tools for reliable calculation of copy numbers from exome sequencing data on cancer-unrelated samples. The dataset should help to understand somatic mosaicism in cardiovascular diseases and to identify copy number variants by means of more appropriate newer tools in the future.