Retinitis pigmentosa (RP), a clinically and genetically heterogeneous retinal disease, entails abnormalities of the rod and cone photoreceptors or the retinal pigment epithelium, leading to progressive visual loss. 1 Since RP predominantly affects the rods, the visual impairment is usually manifested as night blindness and progressive loss of the visual field. The cones are usually affected at a later stage, allowing preservation of the patient’s daytime vision for several years or even decades. 1 More than 50 different genes or loci are involved in cases of non-syndromic RP. 2 One of these, CNGB1, a gene encoding the beta-subunit of the cGMP-gated channel of the rods, is involved in an autosomal recessive form of nonsyndromic RP (RP45, MIM 613767). Here, we present the first case of RP45 caused by an unequivocal homozygous nonsense variant of CNGB1 identified by run of homozygosity (ROH) analysis. In addition, we review the pathogenic variants of CNGB1 as reported to date (Table 1). 3–13 The pedigree of the family of French origin is shown in Figure 1. The family history revealed the consanguineous marriage of the parents (f= 1/32) but there was no history of RP.

The affected individual was a 51-year-old female who had complained of disturbances in night vision since early childhood. RP, diagnosed at age 23, had led to severe constriction of the visual field by age 45. She had no other medical history and, in particular, no olfactory impairment. She had undergone cataract surgery at age 50 with significant visual improvement. The best corrected visual acuity, assessed using the ETDRS chart, was 20/25 in both eyes, with optical correction of plano (− 50) 30 in the right eye and+ 0.25 (− 1.50) 175 in the left eye. Fundus examination revealed a waxy pallor of the optic discs, slightly narrowed retinal vessels, and pigmentary changes in the fundus periphery, which relatively spared the macular region (Figure 2A). Fundus autofluorescence showed a high density perimacular ring characteristic of RP (Figure 2B). The macular function was preserved as confirmed by spectral domain optical coherence tomography, which showed normal macular structure (Figure 2C). The visual