Identification of pathogenic variant enriched regions across genes and gene families

E-print/Working paper (2019)

Missense variant interpretation is challenging. Essential regions for protein function are conserved among gene family members, and genetic variants within these regions are potentially more likely to ... [more ▼]

Missense variant interpretation is challenging. Essential regions for protein function are conserved among gene family members, and genetic variants within these regions are potentially more likely to confer risk to disease. Here, we generated 2,871 gene family protein sequence alignments involving 9,990 genes and performed missense variant burden analyses to identify novel essential protein regions. We mapped 2,219,811 variants from the general population into these alignments and compared their distribution with 65,034 missense variants from patients. With this gene family approach, we identified 398 regions enriched for patient variants spanning 33,887 amino acids in 1,058 genes. As a comparison, testing the same genes individually we identified less patient variant enriched regions involving only 2,167 amino acids and 180 genes. Next, we selected de novo variants from 6,753 patients with neurodevelopmental disorders and 1,911 unaffected siblings, and observed a 5.56-fold enrichment of patient variants in our identified regions (95% C.I. =2.76-Inf, p-value = 6.66×10−8). Using an independent ClinVar variant set, we found missense variants inside the identified regions are 111-fold more likely to be classified as pathogenic in comparison to benign classification (OR = 111.48, 95% C.I = 68.09-195.58, p-value < 2.2e−16). All patient variant enriched regions identified (PERs) are available online through a user-friendly platform for interactive data mining, visualization and download at http://per.broadinstitute.org. In summary, our gene family burden analysis approach identified novel patient variant enriched regions in protein sequences. This annotation can empower variant interpretation. [less ▲]

Guideline-based and bioinformatic reassessment of lesion-associated gene and variant pathogenicity in focal human epilepsies

in Epilepsia (2018)

Objective: Increasing availability of surgically resected brain tissue from patients with focal epilepsy and Focal Cortical Dysplasia (FCD) or low-grade glio-neuronal tumors has fostered large-scale ... [more ▼]

Objective: Increasing availability of surgically resected brain tissue from patients with focal epilepsy and Focal Cortical Dysplasia (FCD) or low-grade glio-neuronal tumors has fostered large-scale genetic examination. However, assessment of pathogenicity of germline and somatic variants remains difficult. Here, we present a state of the art evaluation of reported genes and variants associated with epileptic brain lesions. Methods: We critically re-evaluated the pathogenicity for all neuropathology-associated variants reported to date in PubMed and ClinVar databases including 101 neuropathology-associated missense variants encompassing 11 disease-related genes. We assessed gene variant tolerance and classified all identified missense variants according to guidelines from the American College of Medical Genetics and Genomics (ACMG). We further extended the bioinformatic variant prediction by introducing a novel gene-specific deleteriousness ranking for prediction scores. Results: Application of ACMG guidelines and in silico gene variant tolerance analysis classified only seven out of 11 genes to be likely disease-associated according to the reported a disease mechanism, while 61 (60.4%) of 101 variants of those genes were classified as of uncertain significance (VUS), 37 (36.6%) as being likely pathogenic (LP) and 3 (3%) as being pathogenic (P). Significance: We concluded that the majority of neuropathology-associated variants reported to date do not have enough evidence to be classified as pathogenic. Interpretation of lesion-associated variants remains challenging and application of current ACMG guidelines is recommended for interpretation and prediction. [less ▲]