A case of the mother’s Lynch syndrome diagnosed by genetic counseling with the onset of the daughter’s breast cancer

Abstract

　We experienced a case in which a mother was diagnosed with Lynch syndrome after genetic counseling following the diagnosis of breast cancer.　A 48-year-old woman visited our department for a left breast mass and was diagnosed with left breast cancer by close examination. She was then hospitalized for surgical purposes. A more detailed family history interview by a certified genetic counselor revealed a family history of colorectal cancer among many members in her maternal lineage that could not be obtained by the interview at the first visit. Because of suspected Lynch syndrome, the patient's mother underwent genetic testing after genetic counseling. As a result of the examination, a pathological mutation of MSH2 was found, which led to the diagnosis of Lynch syndrome. No pathogenic mutation in MSH2 was found in the patient. It was suggested that detailed family history interviews could lead to the diagnosis of hereditary diseases in families.