Ocular phenotype of CORD5, an autosomal dominant cone‐rod dystrophy associated with a Q626H mutation in the PITPNM3

Purpose The aim of the study was to describe the phenotype of CORD5, an autosomal dominant retinal dystrophy with a mutation Q626H in the PITPNM3/Nir1 gene encoding the PITPNM3 protein. Methods The study included 33 individuals from two different families, all heterozygous for a Q626H mutation in the PITPNM3/Nir1 gene. Ophthalmological examination including kinetic perimetry, and in selected cases adaptometry, colour vision tests, OCT and electrophysiological studies were performed. In some case the data was obtained from medical records. Results A majority of patients presented symptoms with subnormal visual acuity and light sensitivity from childhood. Signs of macular degeneration were observed early as well. There was a progressive decrease of visual acuity leading to legal blindness in early adulthood in some cases. Electrophysiological testing showed a progressive loss of photoreceptor function restricted to the cones. There seems to be a difference regarding severity of clinical manifestations between the families. Conclusion Our observations and electrophysiological findings indicate a phenotype in CORD5 with loss of photoreceptor function restricted to the cones. An intra‐familial and inter‐familial difference regarding severity of clinical picture was noted.