RT Journal Article SR Electronic T1 Ribosomal protein S6 kinase beta-1 gene variants cause hypertrophic cardiomyopathy JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 984 OP 992 DO 10.1136/jmedgenet-2021-107866 VO 59 IS 10 A1 Jain, Pratul Kumar A1 Jayappa, Shashank A1 Sairam, Thiagarajan A1 Mittal, Anupam A1 Paul, Sayan A1 Rao, Vinay J A1 Chittora, Harshil A1 Kashyap, Deepak K A1 Palakodeti, Dasaradhi A1 Thangaraj, Kumarasamy A1 Shenthar, Jayaprakash A1 Koranchery, Rakesh A1 Rajendran, Ranjith A1 Alireza, Haghighi A1 Mohanan, Kurukkanparampil Sreedharan A1 Rathinavel, Andiappan A1 Dhandapany, Perundurai S YR 2022 UL http://jmg.bmj.com/content/59/10/984.abstract AB Background Hypertrophic cardiomyopathy (HCM) is a genetic heart muscle disease with preserved or increased ejection fraction in the absence of secondary causes. Mutations in the sarcomeric protein-encoding genes predominantly cause HCM. However, relatively little is known about the genetic impact of signalling proteins on HCM.Methods and results Here, using exome and targeted sequencing methods, we analysed two independent cohorts comprising 401 Indian patients with HCM and 3521 Indian controls. We identified novel variants in ribosomal protein S6 kinase beta-1 (RPS6KB1 or S6K1) gene in two unrelated Indian families as a potential candidate gene for HCM. The two unrelated HCM families had the same heterozygous missense S6K1 variant (p.G47W). In a replication association study, we identified two S6K1 heterozygotes variants (p.Q49K and p.Y62H) in the UK Biobank cardiomyopathy cohort (n=190) compared with matched controls (n=16 479). These variants are neither detected in region-specific controls nor in the human population genome data. Additionally, we observed an S6K1 variant (p.P445S) in an Arab patient with HCM. Functional consequences were evaluated using representative S6K1 mutated proteins compared with wild type in cellular models. The mutated proteins activated the S6K1 and hyperphosphorylated the rpS6 and ERK1/2 signalling cascades, suggesting a gain-of-function effect.Conclusions Our study demonstrates for the first time that the variants in the S6K1 gene are associated with HCM, and early detection of the S6K1 variant carriers can help to identify family members at risk and subsequent preventive measures. Further screening in patients with HCM with different ethnic populations will establish the specificity and frequency of S6K1 gene variants.Data are available upon reasonable request. All data relevant to the study are included in the article or uploaded as supplementary information. Not applicable.