Purpose:
Alterations of the CHM gene, which encodes for Rab escort protein 1 (REP1), are responsible for choroideremia. Here we describe a large family with a novel mutation in CHM.
Methods:
Female carriers as well as affected males in the family were characterized using wide field fundus photography, wide field autofluorescence, fluorescein angiography, and electrophysiology.
Results:
A large family with a novel CHM mutation (T1194G) resulting in a premature stop (Y398X) and loss of the final 1/3 C-terminal portion of the protein was identified. One large pedigree was generated of which six males (ages 27-34) and 4 females (ages 48-89) were evaluated. There was a wide range of variability amongst the female carriers, ranging from mild pigmentary alterations (figure, middle panel) to several females exhibiting severe vision loss. Central macular atrophic changes were seen in these severely affected females (figure, top panel). Young affected males mostly showed characteristic peripheral alterations with islands of relative macular sparing (figure, bottom panel). Autofluorescence demonstrating subfoveal loss or absence of RPE predicted visual loss in both sexes (figure).
Conclusions:
Within a single family, female carriers show a remarkable degree of variability. Wide field autofluorescence imaging yielded useful insights into disease severity.
Keywords: retinal degenerations: hereditary • choroid • retinal pigment epithelium