This spontaneous G-to-A point transition at the last position in exon 8 affects splice donor G-GT by changing it to A-GT. This results in the use of a cryptic splice donor A-GT 28 bp downstream. The resulting 3' extension of exon 8 by 28 bp results in a frameshift. Immunohistochemistry does not detect this protein in the dendritic tips of depolarizing bipolar cells in the retina indicating that this is a null allele. (J:229885)