This case study centers on “Tom,” a 43-year-old male patient, and his recent genetic sequencing results and diagnosis of multiple endocrine neoplasia type 2 (MEN2A). Tom has a heterozygous mutation within the RET gene, a proto-oncogene, which contributes to this autosomal dominant disease exhibiting a spectrum of phenotypes, including thyroid cancer. These results raise issues not only with his own treatment but with the potential testing of his two children and unborn child. This directed case, suitable for undergraduate genetics or upper-level cell biology students, integrates multiple inheritance-based concepts. Through Tom’s situation, students examine the effects of his mutation at the cellular level as they navigate national bioinformatics repositories to understand the biological basis of the disease. Specifically, students apply and interpret patterns of inheritance while exploring how mutations disrupt cell cycling contributing to the clinical symptoms and oncogenesis.  With foundational knowledge of the disease, students consider Tom’s family history and reconcile genetic testing recommendations with ethical and parental considerations for the testing of adults, children, and pregnant women.