Cowden syndrome is classically associated with mutations in the phosphatase and tensin homolog (PTEN) gene on chromosome 10q22–23, although variants in several other genes have been described in patients without PTEN mutations (SDHB-D, SEC23B, KLLN, PARP4, AKT1, PIK3CA, USF3, TTN, MUTYH, RET, TSC2, BRCA1, BRCA2, ERCC2, HRAS, and RASAL1) [19,30,31,32]. The gene discussed is RASAL1; the disease is Cowden disease.