Unilateral Cataract and Retinitis Pigmentosa in a Patient With Polyneuropathy, Hearing Loss, Ataxia, Retinitis Pigmentosa, and Cataract (PHARC) Syndrome: A Case Report

Patients with mutations in the alpha/beta -hydrolase (ABHD) 12 gene develop ocular complications including cataracts and retinitis pigmentosa (RP), as part of the polyneuropathy, hearing loss, ataxia, RP, and cataract (PHARC) syndrome. A chart review on a patient with a heterozygous mutation on the ABHD12 gene underwent a comprehensive ophthalmic evaluation. Visual acuity was 0 and 1.3 (logMAR) on the right eye (OD) and left eye (OS), respectively. There was pseudophakia in the OS. Fundus examination in OD was normal and pale optic nerve, attenuated vessels, cystoid macular edema, and mid -peripheral bony spicules were found in OS. Visual field test showed a ring scotoma in the OS. Macular optical coherence tomography (OCT) and fundus autofluorescence were compatible with cystoid macular edema of the OS. The electroretinogram (ERG) of left eye was flat. Patient's systemic findings included: polyneuropathy and hearing loss. Unilateral presentation of cataract and RP in a patient with a heterozygous pathogenic mutation on the ABHD12 gene is rare. This could be due to mosaicism. Retinal follow-up is warranted in this patient since manifestations may occur later in the contralateral eye. A heterozygous pathogenic mutation on the ABHD12 gene may lead to partial ocular and systemic manifestations of the PHARC syndrome.