Retinal and head MRI imaging of patients carrying the p.Ser16Pro variant in PRPS1 . A-E. Retinal imaging of both eyes (BE) of the proband IV:3 at age 35. (A-B) Fundus photographies show pale and atrophic papilla, narrowed vessels, diffuse hypopigmentation, bone spicules, and retinal pigment epithelium (RPE) atrophy in the mid-periphery of BE, and a well-defined atrophic macular lesion in the right eye (RE). (C) Autofluorescence reveals hypofluorescence areas corresponding with pigmented spicules and atrophic lesions. (D) Optical coherence tomography (OCT) confirms the generalized atrophy in all retinal layers in both perifoveal and foveal regions in RE. Well-conserved retinal architecture was found in the left eye (LE) and the atrophy is restricted to RPE and external layers. (E) Head MRI scan of the proband IV:3 demonstrates a moderate cerebellar atrophy (white arrows). F-J. Retinal imaging of BE of IV:2 at age 37. (F-G) Fundus photographies show a slight pallor in the papilla, slight arteriolar attenuation mainly around the optic nerve, a normal macula and an incipient RPE atrophy. (H) Normal autofluorescence. (I) OCTs display atrophy of photoreceptors layer in the perifoveal region and normal foveal thickness. (J) Head MRI scan of individual IV:2 does not evidence any sign of cerebellar atrophy. K-O. Retinal imaging of BE of III:2 at age 70. (K-L) Fundus photographies evidence pale and atrophic papilla, substantially narrowed vessels, sparse pigmentation, patches of chorioretinal atrophy in the mid-periphery of BE, and a well-defined atrophic macular lesion in RE and RPE alteration in LE. (M) Autofluorescence imaging shows alternating areas of hypo and hyperfluorescence. (N) OCT shows subfoveal atrophy lesion with loss of retinal architecture, an epiretinal membrane in RE and defects in external layer in LE. (O) Head MRI scan of individual III:2 exhibits a mild cerebellar atrophy (white arrow).