Definition:A retinal degeneration characterized by the gradual deterioration of the photoreceptors or the retinal pigment epithelium of the retina leading to progressive sight loss.
Definition:A specific developmental disorder that involves significant limitations both in mental functioning and in adaptive behavior such as communicating, taking care of him or herself, and social skills.
Definition:A cerebral creatine deficiency syndrome that is characterized by mental retardation, severe speech delay, behavioral abnormalities and seizures, has_material_basis_in mutation in the SLC6A8 gene on chromosome Xq28.