APC and Down syndrome: Non‐medullary TCa may occur in families (familial non‐medullary TCa) or as component tumors of syndromes that include familial adenomatous polyposis (FAP) (APC gene), PTEN hamartoma syndrome (PTEN and others), Carney complex (PRKAR1A gene), Werner syndrome (WRN gene), and DICER1 syndrome (DICER1 gene),1, 2 but the full contribution of genes related to hereditary risk of TCa is not yet established.