Norrin, also known as Norrie disease protein or X-linked exudative vitreoretinopathy 2 protein (EVR2) is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
that in humans is encoded by the ''NDP''
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
.
Mutations in the NDP gene are associated with the
Norrie disease
Norrie disease is a rare disease and genetic disorder that primarily affects the eyes and almost always leads to blindness. It is caused by mutations in the ''Norrin cystine knot growth factor (NDP)'' gene, which is located on the X chromosome. In ...
.
Function
Signaling induced by the protein Norrin regulates
vascular
The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away f ...
development of vertebrate retina and controls important blood vessels in the ear.
Norrin binds with high affinity to Frizzled 4, and Frizzled 4 knockout mice exhibit abnormal vascular development of the retina.
Clinical significance
NDP is the genetic locus identified as harboring mutations that result in Norrie disease. Norrie disease is a rare genetic disorder characterized by bilateral congenital blindness that is caused by a vascularized mass behind each lens due to a maldeveloped retina (pseudoglioma).
References
External links
GeneReviews/NIH/NCBI/UW entry on NDP-Related Retinopathies
Further reading
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Human proteins
{{gene-X-stub