This 42YO female with type 2 diabetes was referred for asymptomatic diabetic macular edema (DME). There was no family history of ocular disease. Vision was 20/40 OD and 20/20 OS.
Optos color RGB imaging shows diffuse coarse subretinal hyperpigmentations throughout each posterior pole. Fundus autofluorescence (FAF) shows variable hyper- and hypo-FAF from these pigmentary changes, with fluorescein angiographic window defects. Genetic testing revealed a heterozygous pathogenic CHM mutation.
Learning Points:
Choroideremia is an X-linked recessive chorioretinal dystrophy caused by a mutation in the CHM gene located on the long arm of the X chromosome. Sons of female carriers have a 50% chance of developing choroideremia, and daughters have a 50% chance of becoming carriers. Some female carriers can develop asymptomatic pigmentary changes, as in our patient, or frank choroideremia due to irregular inactivation of the X chromosome (see Jauregui et al, AJO 2019;207:77-86).
