Purpose  To investigate the choroideremia (CHM) gene in two families with choroideremia, and to characterize the related clinical features.
Methods  Two families underwent complete ophthalmic examinations and three males were diagnosised as choroideremia. Genomic DNA was extracted from leukocytes of peripheral blood collected from the two families and 100 unrelated control subjects from the same population. Exons 1–15 of the CHM gene were amplified by polymerase chain reaction (PCR) and directly sequenced. We performed ophthalmic examinations including best-corrected visual acuity, slit-lamp examination, fundus examination, visual field, optical coherence tomography(OCT), electroretinogram(ERG), Pentacam and Goldmann perimetry.
Results  The affected men were hemizygous and had night-blindness, chorioretinal atrophy spreading from the posterior pole to the mid-periphery, and bareness of the sclera. A novel c.1488delinsATAAC mutation was detected in the CHM gene in the Family 1. Another mutation c. 1703 C> G (S558X) within exon 14 of the CHM gene was identified in Family 2, which caused changing the serine 558 codon (TCA) to a stop codon (TGA).
Conclusion  The present study has identified a novel mutation in CHM associated with choroideremia. Our finding expands the genotypic spectrum of CHM mutations associated with choroideremia and confirms the role of Rab escort protein-1 in the pathogenesis of choroideremia.