A New Phenotypic Expression in a Patient With a Mutation in the CACNA1F Gene.

Mutations in the CACNA1F gene are associated with various X-linked retinal disorders, including congenital stationary night blindness type 2A (CSNB2A), cone-rod dystrophy (CORDX3), and Åland Island eye disease (AIED), due to their role in calcium channel function in retinal photoreceptor synapses. In this report, we present the case of a 33-year-old Hispanic male patient with childhood-onset nyctalopia and progressive visual loss. Fundus examination revealed optic disc pallor and cupping, vascular attenuation, chorioretinal atrophy, and mid-peripheral bony spicules. Full-field electroretinography (ERG) demonstrated severely reduced scotopic and photopic responses, with non-discernible a- and b-waves and significantly diminished 30 Hz flicker amplitudes with delayed peak times. Humphrey visual field testing showed bilateral peripheral field constriction. A clinical diagnosis of retinitis pigmentosa was made. Genetic testing via next-generation sequencing revealed a hemizygous pathogenic mutation in CACNA1F, specifically c.5037_5038del (p.Leu1681Alafs*16), leading to a truncated, non-functional protein. While this variant has been reported in genetic databases, detailed phenotypic descriptions remain scarce. Our findings are most consistent with cone-rod dystrophy, although visual field defects also overlap with features of AIED. This case highlights the phenotypic heterogeneity of CACNA1F-related disorders and suggests rod-cone dystrophy as a potential additional phenotype. Further studies are warranted to clarify the full clinical spectrum and molecular mechanisms associated with CACNA1F mutations.