In this NIH Intramural Research Program (IRP), researchers are examining potential genetic contributions to a wide variety of disorders, including autism, attention deficit hyperactivity disorder (ADHD), eye disorders (i.e., glaucoma, myopia), and rare neurological syndromes. In their genetic study of autism, researchers have found evidence for a genetic linkage of autistic individuals with hypocholesterolemia, which is defined by the presence of abnormally low (hypo-) levels of cholesterol in the blood (-emia). Confirmation in additional data is underway, and additional family data are being collected. Whole-exome sequencing of autistic patients with extreme cholesterol values and a sibling with either autism or autism spectrum disorder (ASD) is being performed to search for rare variants of large effect in this subset of patients with familial autism/ASD. This study will also be extended to include autistic patients with extreme hypocholesterolemia but who do not have siblings affected with ASD.