Novel MFSD8 mutation causing non-syndromic asymmetric adult-onset macular dystrophy

Background: MFSD8 mutations can cause type 7 neuronal ceroid lipofuscinosis, a systemic disorder that includes vision loss; however, such mutations can also cause isolated retinal dystrophy with vision loss without systemic signs or symptoms as first identified in 2015. This report details a previously unreported combination of compound heterozygous variants in the MFSD8 gene causing a non-syndromic, bilateral central macular dystrophy presenting in adulthood. Materials and Methods: We present a case of MFSD8-associated retinal dystrophy with multimodal imaging and a review of relevant literature. Results: A 57-year-old female presented for subacute, unilateral blurriness in her right eye. Best corrected visual acuity was 20/250 and 20/50 in the right and left eyes, respectively. Fundus examination and multimodal imaging revealed blunted foveal reflexes and optical gap with subfoveal ellipsoid zone loss in both eyes, right greater than left. Full field electroretinography results were within normal limits while the Arden ratio on electro-oculography was abnormal in both eyes, right more so than left. Genetic testing revealed apparently causative compound heterozygous mutations in the MFSD8 gene: c.154G>A, p.(Gly52Arg) and c.1006G>C, p.(Gluc336Gln). Visual acuity over one year of follow-up has remained stable. Conclusions: To authors’ knowledge, this report is first description of this combination of mutations in the MFSD8 gene leading to non-syndromic adult-onset macular dystrophy.