Two-hit mutation causes Wilms tumor in an individual with FBXW7-related neurodevelopmental syndrome.

FBXW7 (F-box and WD-repeat domain-containing 7) is a tumor suppressor gene, and its germline variants have been causally linked to Wilms tumors. Furthermore, germline variants of FBXW7 have also been implicated in a neurodevelopmental syndrome. However, little is known regarding the occurrence of Wilms tumor in patients with FBXW7-related neurodevelopmental syndrome. We identified a novel constitutional pathogenic variant of FBXW7 in a patient with intellectual disability, who also developed Wilms tumor. The variant was derived from his apparently normal mother, and was also detected in his sister who exhibited developmental delay. Furthermore, we detected a somatic nonsense variant on the paternal allele of FBXW7 in the tumor DNA. These results suggest that the development of Wilms tumor along with FBXW7-related neurodevelopmental syndrome follows the two-hit model, which needs to be validated to establish appropriate follow-up management and tumor surveillance.