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.²GRM6 encodes the glutamate receptor MGluR6, which is expressed by the rod and cone ON bipolar cells.³ Pharmacological block of this receptor in primates^4,5 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 …