Discovery of selfish mutations expanding in the male germline with duplex sequencing
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ESHG 2019 Conference
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Introduction: De novo mutations (DNM) are an important player in heritable diseases and evolution, yet little is known about the different mutagenic processes in our germline. Of interest are a few highly recurrent DNM associated with congenital disorders and/or rasopathies, that have been described as selfish mutations expanding in the male germline. We have adapted an ultra-sensitive sequencing (USS) technology based on duplex-barcoding to distinguish both DNA strands, thus increasing the sensitivity to one mutation in 107 sequenced bases. This technology was applied to study the expansion of selfish mutations in the FGFR3 gene in the male germline.
Materials and Methods: A ~3000bp coding region of the FGFR3 gene including the transmembrane and the tyrosine kinase domains was sequenced with USS in two DNA sperm pools from an old and young donor group.
Results: DNM with frequencies of 10-3 ? 10-5 were identified in 41 exonic positions, several of which have been described in congenital disorders and/or cancer. The achondroplasia associated mutation c.1138G>A was detected at similar frequencies as the reported occurrence. Also, various substitutions are viable and have been reported in population data (gnomAD), albeit at lower frequencies. Mutations found in both pools show higher frequencies in older donors.
Conclusions: Our USS method has proven to be successful in detecting low frequency DNM. Also, it is an important strategy to identify driver mutations in the male germline expanding with paternal age with potentially important health consequences.
Project funded by the Linz Institute of Technology (LIT213201001) and FWF (FWF308667000).