Maria L Stunkel, Scott E Brodie, Artur V Cideciyan, Wanda L Pfeifer, Elizabeth L Kennedy, Edwin M Stone, Samuel G Jacobson, Arlene V Drack

GUCY2D has been associated with autosomal recessive Leber Congenital Amaurosis and autosomal dominant cone-rod dystrophy. This report expands the phenotype of autosomal recessive mutations to congenital night blindness which may slowly progress to retinitis pigmentosa. Retrospective case series. Multicenter study of five patients (3 male, 2 female). All presented with night blindness since childhood. Age at referral was 9-45 years. Length of follow up was 1-7 years. Best corrected visual acuity at presentation ranged from 20/15 to 20/30 and at most recent visit averaged 20/25. No patient had nystagmus or high refractive error. ISCEV standard electroretinography revealed non-detectable dark adapted dim flash responses, reduced amplitude but not electronegative dark adapted bright flash responses with similar waveforms to the reduced amplitude light adapted single flash responses. 30 Hz flicker responses were relatively preserved. Macular optical coherence tomography revealed normal lamination in 3, with abnormalities in 2. Goldmann visual fields were normal at presentation in children but constricted in one adult. One child showed loss of mid-peripheral fields over time. Fundus appearance was normal in childhood; the adult had sparse bone-spicule-like pigmentation. Full field stimulus testing (FST) revealed markedly decreased retinal sensitivity to light. Dark adaptation demonstrated lack of rod-cone break. 2 patients had tritanopia. All 5 had compound heterozygous mutations in GUCY2D. Three of the 5 patients harbor the Arg768Trp mutation reported in GUCY2D-associated Leber Congenital Amaurosis. Autosomal recessive GUCY2D mutations may cause congenital night blindness with normal acuity and refraction, and unique electroretinography. Progression to mild retinitis pigmentosa may occur.