DISCOVERY OF selfish MUTATIONS WITH ULTRA-SENSITIVE SEQUENCING
Sprache des Vortragstitels:
Annual Meeting of the German Society of Human Genetics
Sprache des Tagungstitel:
New mutations in the germline are directly transmitted to our children and have therefore profound consequences in future generations. Surprisingly, despite the importance of de novo mutations (DNM) in heritable disease and our evolution, we know very little about the different mutagenic processes in our germline. Of particular interest are a handful of highly recurrent DNM associated with congenital disorders and/or rasopathies, that have been described as driver mutations expanding in the male germline. The mutation itself causes a change in the tyrosine kinase receptor/Ras/MAPK pathway, which in turn confers the spermatogonial stem cell a proliferative advantage. Selfish or driver mutations are quite common in cancer, but we still know very little about the selfish expansion in the male germline. The reason might be that mutations in the human germline are very rare, and it is rather difficulty to directly measure such rare events. Most of our knowledge on germline mutagenesis comes from indirect sequence comparisons or whole genome sequencing of pedigree families, but it renders little information about individual mutagenic events. For this reason, we have adapted an ultrasensitive, next generation sequencing (USS) technology for the measurement of rare mutations to study the expansion of selfish genes in the male germline. As a proof-of-principle, we have sequenced at an extremely high coverage exon 10 and 15 of the FGFR3 gene in young and old sperm donors. We found an increased mutation frequency for the loci associated with achondroplasia and thanatophoric dysplasia II in sperm of older donors. Our results also show that we can distinguish ultra-rare mutations occurring at a frequency of one in hundred thousand wild type; thus, making this method ideal to discover potential driver DNM that might be expanding with paternal age.