Retinal dystrophy associated with a Kizuna (KIZ) mutation and a predominantly macular phenotype

Introduction: Mutations in Kizuna (KIZ), a gene involved in ciliary function, have been previously associated with rod-cone dystrophy with relative macular sparing and a number of other systemic abnormalities.Purpose: We present a patient with a phenotype dominated by retinal dystrophy and macular cysts as a result of a homozygous nonsense mutation in KIZ.Methods: A 32-year-old female of Ashkenazi Jewish ancestry presented with progressive central vision loss and peripheral visual field loss following decades of night-blindness. She was noted to have a bull's-eye pattern of macular hyper-autofluorescence, intraretinal cystoid macular changes and outer retinal atrophy in both eyes. Visual fields were constricted to <10 degrees centrally with inferior preserved islands of vision. Genetic testing revealed a homozygous KIZ c.226 C > T (p.Arg76*) nonsense mutation. The patient was treated with topical dorzolamide and showed significant improvement in the degree of macular cysts.Conclusion: Mutations in KIZ can present with a predominantly macular phenotype and develop cystoid macular changes responsive to carbonic anhydrase inhibitor treatment. Because of the importance of KIZ in cilia function, it is critical to look for associated systemic manifestations to ensure best patient care.