Advanced Choroideremia Linked to a Rare Missense Variant in the CHM Gene

Choroideremia is an X-linked inherited chorioretinal dystrophy leading to blindness by late adulthood. Choroideremia is caused by mutations in the CHM gene, which encodes Rab escort protein 1 (REP1), a ubiquitously expressed protein involved in intracellular trafficking and prenylation activity.

We report a 48-year-old male with an 18-year history of progressive night vision impairment. Fundoscopic examination revealed sharply demarcated regions of chorioretinal atrophy, primarily around the optic nerve. Bone spicules were observed throughout the retina, particularly at the margins of the atrophic areas, with preservation of the macula. Electroretinography (ERG) demonstrated a diminished response. Genetic testing confirmed a hemizygous missense variant in the CHM gene (CHM: NM_000390:exon11:c.1413G>C:p.Q471H), establishing the diagnosis.

This case, supported by clinical findings, multimodal retinal imaging, and genetic analysis, confirms that this CHM variant is pathogenic and contributes to choroideremia.