STX1A and Williams syndrome: Moreover, STX1A (encoding Syntaxin-1A) is one of approximately 28 genes within a commonly deleted region in Williams Syndrome (or Williams-Beuren Syndrome, OMIM 194050), a multi-system developmental syndrome with features such as connective tissue abnormalities, cardiovascular disease, mild intellectual disability, delayed motor development, unique social and personality characteristics, and growth and endocrine abnormalities (99, 100).