Browsing by Subject "De novo"

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  • Alhopuro, Pia; Vainionpää, Reetta; Anttonen, Anna-Kaisa; Aittomäki, Kristiina; Nevanlinna, Heli; Pöyhönen, Minna (2020)
    Germline mutations in theBRCA1andBRCA2genes cause hereditary breast and ovarian cancer syndrome (HBOC). Mutations in these genes are usually inherited, and reports ofde novo BRCA1/2mutations are rare. To date, only one patient with low-levelBRCA1mutation mosaicism has been published. We report on a breast cancer patient with constitutional somatic mosaicism of aBRCA2mutation.BRCA2mutation c.9294C>G, p.(Tyr3098Ter) was detected in 20% of reads in DNA extracted from peripheral blood using next-generation sequencing (NGS). TheBRCA2mutation was subsequently observed at similar levels in normal breast tissue, adipose tissue, normal right fallopian tube tissue and ovaries of the patient, suggesting that this mutation occurred early in embryonic development. This is the first case to report constitutional mosaicism for aBRCA2mutation and shows thatBRCA2mosaicism can underlie early-onset breast cancer. NGS forBRCA1/2should be considered for patients whose tumors harbor aBRCA1/2mutation and for individuals suggestive of genetic predisposition but without a family history of HBO.