Identification of a secondary mutation in a pediatric patient with relapsed acute myeloid leukemia leads to the diagnosis and treatment of asymptomatic metastatic medullary thyroid cancer in a parent: a case for sequencing the germline.

The incorporation of tumor-normal genomic testing into oncology can identify somatic mutations that inform therapeutic measures but also germline variants associated with unsuspected cancer predisposition. We describe a case in which a variant was identified in a 3-yr-old male with relapsed leukemia. Sanger sequencing revealed the patient's father and three siblings carried the same variant, associated with multiple endocrine neoplasia 2A (MEN2A).