ClinVar Genomic variation as it relates to human health

This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease.

Variant summary: RYR2 c.10231-5C>T alters a non-conserved nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. 4/4 computational tools predict no significant impact on normal splicing, however, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 0.00054 in 226606 control chromosomes in the gnomAD database, including 1 homozygote. The observed variant frequency is approximately 16 fold of the estimated maximal expected allele frequency for a pathogenic variant in RYR2 causing Catecholaminergic Polymorphic Ventricular Tachycardia (3.4e-05), strongly suggesting that the variant is benign. To our knowledge, no occurrence of c.10231-5C>T in individuals affected with Catecholaminergic Polymorphic Ventricular Tachycardia and no experimental evidence demonstrating its impact on protein function have been reported. Five ClinVar submitters have assessed the variant since 2014: one classified the variant as VUS, three as likely benign, and one as benign. Based on the evidence outlined above, the variant was classified as benign.

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity.

RYR2: BP4, BS1

c.10231-5C>T in intron 70 of RYR2: This variant is not expected to have clinica l significance because a C>T change at this position does not diverge from the s plice consensus sequence and is therefore unlikely to impact splicing. It has be en identified in 0.2% (7/3350) of Latino chromosomes and 0.1% (41/29276) of Euro pean chromosomes by the Exome Aggregation Consortium (ExAC, http://exac.broadins titute.org; dbSNP rs186326951).

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease.

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease.