Consistent with the deleteriousness of diminished or absence of AFF3 expression, these fourteen individuals (10 males and 4 females) shared common phenotypes such as global DD/ID (11 out of 11), abnormal corpus callosum (4/6), speech impairment (10/11), muscle disorders/hypotonia (7/9), facial dysmorphisms (6/7), mild cranial dysmorphisms (3/8), and skeletal defects (4/7). The gene discussed is AFF3; the disease is muscular disease.