Intraretinal cystoid spaces in a patient with retinitis pigmentosa due to mutation in the MAK gene.

Cystoid macular edema (CME) and non-leaking intraretinal cystoid spaces (ICS) have different pathophysiologic mechanisms.

We report a patient with retinitis pigmentosa (RP) with ICS due to a mutation in the male germ cell-associated kinase (MAK) gene.

A 41-year-old Ashkenazi Jewish male was referred for abnormal visual field revealed by regular optometric examination. His visual acuity was 20/20 in each eye. Dilated examination revealed typical finding of RP. Optical coherence tomography showed cystoid changes in each fovea. Photoreceptors were also degenerated. Intravenous fluorescein angiography showed no leakage. Genetic testing identified a homozygous mutation in the MAK gene: a 353-bp Alu insertion (K429insAlu).

Mak regulates microtubule stability via phosphorylating RP1. Abnormal Mak may impact retinal photoreceptor ciliary length and subcompartmentalization. Mak is required for the survival of photoreceptors in mice. ICS has been reported in other ciliopathies. We report the first case of ICS due to mutation in MAK.