PMC5158031_01
Validation and co-segregation of GNAT1 variant in family F780.. The pedigree and the respective electropherograms of each tested family member are depicted. Family F780 is composed of two unaffected parents (father: I.1, CIC01294; mother: I.2, CIC06690), one affected son (II.1; CIC01293) and one unaffected son (II.2). The nonsense variant c.963C>A p.(Cys321*) [M] in GNAT1 (NM_144499.2; MIM *139330) was found homozygous in the affected boy (II.1, CIC01293), heterozygous in the unaffected mother (I.2, CIC06690) and absent in the unaffected father (I.1, CIC01294). Females and males are depicted by circles and squares, respectively. Filled and unfilled symbols indicate affected and unaffected status, respectively. The arrow indicates the nucleotide position 963 heterozygously and homozygously changed in the mother and index patient, respectively, and unchanged in the father.
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The proband CIC01293 (Fig 2) was a 32 year-old male subject at the time of examination.
Clinical observations.. (A) Color vision test with the Farnworth desaturated 15HUE shows a tritan axis defect. (B) Kinetic visual field tests demonstrate visual field constriction in both eyes. (C) Color fundus photographs reveal optic nerve pallor, narrowed retinal vessels, pigment clumping in retinal periphery some of which resembling more to coarse nummular pigments rather than classical bone spicules, as well as perifoveal atrophic changes. (D) Short-wavelength fundus autofluorescence shows hypo-autofluorescence in the periphery as well as in the perifoveal area. In (A, C, D), Ocula dextra (right eye; OD) is presented in the left part and ocular sinistra (left eye; OS) in the right part. (E) SD-OCT reveals thinning of the outer retinal layers. The two first SD-OCT correspond to OD results, the two next to OS results.
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Color vision with desaturated Farnworth 15Hue revealed a tritan axis defect in both eyes (Fig 3A). Kinetic visual field tests showed bilateral abnormalities with a relative preservation of the central 30  with the III4e stimulus (Fig 3B). Fundus examination revealed optic nerve pallor, narrowed retinal vessels, pigment clumping in retinal periphery some of which resembling more to coarse numular pigment rather than classical bone spicules, as well as perifoveal atrophic changes (Fig 3C). In keeping with fundus changes short-wavelength fundus autofluorescence imaging revealed hypo-autofluorescent lesions in the periphery as well as in the perifoveal area (Fig 3D). Spectral Domain Optical Coherence Tomography (SD-OCT) revealed thinning of the outer retinal layers (Fig 3E).