Ngan et al. (2009) examine DNA extracted from blood samples from 20 patients with MNG/PTC, 284 with PTC, and 349 control subjects, for mutations in TITF-1/NKX2.1. Targeted DNA sequencing reveals a germline TITF-1/NKX2.1 A339V mutation in four patients with PTC and a history of MNG. This evidence concerns the gene NKX2-1 and toxic multinodular goitre.