ClinVar Genomic variation as it relates to human health

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.

Lys19758Arg in exon 266 of TTN: This variant is not expected to have clinical si gnificance because it has been identified in 0.4% (12/3048) of African American chromosomes from a broad population by the NHLBI Exome Sequencing Project (http: //evs.gs.washington.edu/EVS). Lys19758Arg in exon 266 of TTN (allele frequenc y = 0.4%, 12/3048) **

Variant summary: TTN c.59273A>G (p.Lys19758Arg) results in a conservative amino acid change located in the A-band region of the encoded protein sequence. Four of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.00049 in 279656 control chromosomes, predominantly at a frequency of 0.0053 within the African or African-American subpopulation in the gnomAD database, including 2 homozygotes. The observed variant frequency within African or African-American control individuals in the gnomAD database is approximately 13.5-fold of the estimated maximal expected allele frequency for a pathogenic variant in TTN causing Dilated Cardiomyopathy phenotype (0.00039), strongly suggesting that the variant is a benign polymorphism found primarily in populations of African or African-American origin. c.59273A>G has been reported in the literature in an African American individual affected with Dilated Cardiomyopathy (Pugh_2014). This report does not provide unequivocal conclusions about association of the variant with Dilated Cardiomyopathy. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Four clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as benign (n=2) / likely benign (n=2). Based on the evidence outlined above, the variant was classified as benign.

TTN: BP4, BS2