extracellular matrix. LRR domains are involved in the protein–protein interaction in small leucine rich repeat proteoglycan family members. Also, LRR domains have a critical role in nyctalopin function. Congenital stationary night blindness in humans appears when a mutation in the LRR domains of nyctalopin occurs. Mutations The complete form of congenital stationary night blindness is due to the absence of nyctalopin. This absence is due to a mutation involving an 85 base pair deletion. In humans, more than 30 mutations are found in the NYX gene and most of them have an impact either on the tertiary structure of the LRR domains of nyctalopin or to truncate the protein. References Further reading External links GeneReviews/NCBI/NIH/UW entry on X-Linked Congenital Stationary Night Blindness Proteoglycans