Congenital stationary night blindness associated with mutations in GRM6 encoding glutamate receptor MGluR6

Congenital stationary night blindness (CSNB) is a non-progressive retinal disorder characterised by defective night vision from birth1 that is clinically and genetically heterogeneous. It is most commonly inherited as an X linked disorder, but autosomal dominant (OMIM #163500) and recessive (OMIM#258100) forms have been described. A recent report describes mutations of the GRM6 gene in three patients with autosomal recessive CSNB.2 GRM6 encodes the glutamate receptor MGluR6, which is expressed by the rod and cone ON bipolar cells.3 Pharmacological block of this receptor in primates4,5 leads to a similar CSNB phenotype as that described in subjects with GRM6 mutations.2 We have previously identified mutations in CACNA1F and NYX genes in males with X linked CSNB,6,7 and have encountered several female patients with a similar phenotype. We screened these affected females for mutations in RHO which can cause autosomal dominant …