It has long been observed that there are families in which thyroid cancer occurs, but no clear causative genes have been found. Some reports showed that shelterin proteins (involved in telomeric regulation) could be related with susceptibility to thyroid cancer. We have found a genetic variant in the TINF2 gene, co-segregating in five affected members of one family. Our results and some previous data reinforce TINF2 gene as a susceptibility cause of familial thyroid and/or melanoma cancers. Furthermore, we point out the importance of location of the variant into the gene to be classified as causative of cancer or not. (By Dr. Josep Oriola, https://jmg.bmj.com/content/early/2024/08/05/jmg-2024-110185 )