Selfish mutations dysregulating RAS-MAPK signaling are pervasive in aged human testes.
Maher, Geoffrey J
Ralph, Hannah K
Paul, Dirk S
Stricker, Stefan H
Cold Spring Harbor Laboratory
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Maher, G. J., Ralph, H. K., Ding, Z., Koelling, N., Mlcochova, H., Giannoulatou, E., Dhami, P., et al. (2018). Selfish mutations dysregulating RAS-MAPK signaling are pervasive in aged human testes.. Genome Res, 28 (12), 1779-1790. https://doi.org/10.1101/gr.239186.118
Mosaic mutations present in the germline have important implications for reproductive risk and disease transmission. We previously demonstrated a phenomenon occurring in the male germline, whereby specific mutations arising spontaneously in stem cells (spermatogonia) lead to clonal expansion, resulting in elevated mutation levels in sperm over time. This process, termed "selfish spermatogonial selection," explains the high spontaneous birth prevalence and strong paternal age-effect of disorders such as achondroplasia and Apert, Noonan and Costello syndromes, with direct experimental evidence currently available for specific positions of six genes (FGFR2, FGFR3, RET, PTPN11, HRAS, and KRAS). We present a discovery screen to identify novel mutations and genes showing evidence of positive selection in the male germline, by performing massively parallel simplex PCR using RainDance technology to interrogate mutational hotspots in 67 genes (51.5 kb in total) in 276 biopsies of testes from five men (median age, 83 yr). Following ultradeep sequencing (about 16,000×), development of a low-frequency variant prioritization strategy, and targeted validation, we identified 61 distinct variants present at frequencies as low as 0.06%, including 54 variants not previously directly associated with selfish selection. The majority (80%) of variants identified have previously been implicated in developmental disorders and/or oncogenesis and include mutations in six newly associated genes (BRAF, CBL, MAP2K1, MAP2K2, RAF1, and SOS1), all of which encode components of the RAS-MAPK pathway and activate signaling. Our findings extend the link between mutations dysregulating the RAS-MAPK pathway and selfish selection, and show that the aging male germline is a repository for such deleterious mutations.
Testis, Humans, ras Proteins, Mitogen-Activated Protein Kinases, Signal Transduction, Mutation, Aged, Aged, 80 and over, Middle Aged, Male, Genetic Variation
We thank the UCL Cancer Institute Genomics and Genome Engineering Core Facility (supported by the Cancer Research UK – UCL Centre), for providing access to the RainDance Thunderstorm platform, which was purchased on a Wellcome multi-user grant (99148). This work was primarily supported by grants from the Wellcome (grant 091182 to A.G., G.McV. and A.O.M.W.; grant 102731 to A.O.M.W. and studentship 105361 to H.K.R.), the Simons Foundation (332759 to A.G.) and the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre Programme (to A.G.). S.B., P.D. and S.H.S. were supported by a Wellcome programme grant and D.S.P. was supported by EU-FP7. We acknowledge funding from the Medical Research Council (MRC) through the WIMM Strategic Alliance (G0902418 and MC_UU_12025) and the support of the High-Throughput Genomics core facility by the Wellcome grant 090532.
Medical Research Council (MR/L003120/1)
European Commission (282510)
British Heart Foundation (None)
External DOI: https://doi.org/10.1101/gr.239186.118
This record's URL: https://www.repository.cam.ac.uk/handle/1810/286700
Attribution 4.0 International
Licence URL: https://creativecommons.org/licenses/by/4.0/