What is Norrie disease?
Norrie disease is a rare genetic condition that causes blindness and other symptoms, usually in boys. Most boys who have Norrie disease are born blind. The majority of affected boys will also develop hearing loss during childhood. About one third to one half (30-50%) of boys with Norrie disease will also have developmental delay, intellectual disability, behavioral problems, or psychotic-like features.
Norrie disease is caused by mutations in the gene NDP. Typically, boys have one X chromosome and one Y chromosome, while girls have two X chromosomes. Boys therefore normally have one copy of NDP, while girls have two copies. A boy with Norrie disease has a mutation in his only copy of NDP. Girls who have a mutation in one copy of NDP are called carriers, and they usually do not have any symptoms of Norrie disease.
SOURCE: Emory University - Department of Human Genetics in collaboration with ThinkGenetic • https://www.thinkgenetic.com/diseases/norrie-disease/overview/1756 • DATE UPDATED: 2016-05-30
Sims KB. NDP-Related Retinopathies. 1999 Jul 30 [Updated 2014 Sep 18]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2016. Available from: http://www.ncbi.nlm.nih.gov/books/NBK1331/[/link]
Norrie Disease Association: http://www.norriedisease.org/norrie-disease-information[/link]