PTEN and Cowden syndrome 1: The phosphatase and tensin homolog hamartoma tumor syndrome (PHTS) refers to a spectrum of disorders caused by variants of the phosphatase and tensin homolog (PTEN) gene, including Cowden syndrome (CS), Bannayan–Riley–Ruvalcaba syndrome, adult Lhermitte–Duclos disease, and autism spectrum disorders associated with macrocephaly.