Germline ATM Variation in a Young Patient Diagnosed with Breast Cancer Presenting with Vaginal Neuroendocrine Carcinoma

ATM plays a crucial role in repairing DNA damage and maintaining genomic stability.Mutations in ATM are associated with increased breast cancer risk and the development of various neuroendocrine carcinomas, including small-cell lung carcinoma and neuroendocrine tumors of the gastrointestinal tract.Here, we present a case with a heterozygous ATM variant [NM_000051.4.7174C>T(p.Arg2392Trp)], which is classified as a variant of uncertain significance (VUS) in the ClinVar database.This patient, who was initially treated for breast cancer, was later diagnosed with a rare vaginal neuroendocrine carcinoma at month 31 post-breast cancer diagnosis.In contrast to most cases, the patient tested negative for human papillomavirus (HPV)-DNA.Based on the rare presentation of neuroendocrine carcinoma and the negative HPV-DNA status, we proposed that VUS of ATM may be associated with cancer development and has pathogenic roles.