title: Congenital hereditary downbeat nystagmus.
abstract: This report describes an 8-year-old boy with congenital hereditary downbeat nystagmus, the youngest person with downbeat nystagmus in the literature to date and the first to have an apparently congenital form. He had tended to keep his chin down since birth and had had difficulty reading since starting to attend school. His 28-year-old mother manifested a subclinical combined rotatory-downbeat nystagmus only in oblique downward gaze. Neither the child nor the mother demonstrated evidence of spinocerebellar degeneration. Homologous base-up prisms incorporated into glasses eliminated his chin-down head posture, improved his vision in primary position and "cured" his so-called learning disability.
mesh_terms: D000328:Adult; D002648:Child; D002675:Child, Preschool; D004410:Dyslexia / Q000209:etiology; D004584:Electronystagmography; D005139:Eyeglasses / Q000592:standards; D005260:Female; D006257:Head; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009759:Nystagmus, Pathologic / Q000151:congenital* / Q000235:genetics / Q000628:therapy; D011187:Posture