Abstract
BackgroundPathogenic variants of G-protein coupled receptor 143 (GPR143) gene often leads to ocular albinism type I (OA1) characterized by nystagmus, iris and fundus hypopigmentation, and foveal hypoplasia. In this study, we identified a novel hemizygous nonsense mutation in GPR143 that caused an atypical manifestation of OA1.Case presentationWe reported a large Chinese family in which all affected individuals are afflicted with poor visual acuity and foveal hypoplasia without signs of nystagmus. Fundus examination of patients showed an absent foveal reflex and mild hypopigmentation. The fourth grade of foveal hypoplasia and the reduced area of blocked fluorescence at foveal region was detected in OCT. OCTA imaging showed the absence of foveal avascular zone. In addition, the amplitude of multifocal ERG was reduced in the central ring. Gene sequencing results revealed a novel hemizygous mutation (c.939G > A) in GPR143 gene, which triggered p.W313X. However, no iris depigmentation and nystagmus were observed among both patients and carriers.ConclusionsIn this study, we reported a novel nonsense mutation of GPR143 in a large family with poor visual acuity and isolated foveal hypoplasia without nystagmus, which further expanded the genetic mutation spectrum of GPR143.
Highlights
Pathogenic variants of G-protein coupled receptor 143 (GPR143) gene often leads to ocular albinism type I (OA1) characterized by nystagmus, iris and fundus hypopigmentation, and foveal hypoplasia
In this study, we reported a novel nonsense mutation of GPR143 in a large family with poor visual acuity and isolated foveal hypoplasia without nystagmus, which further expanded the genetic mutation spectrum of GPR143
We reported and characterized a large Chinese family, in which all the affected individuals are afflicted with poor visual acuity and foveal hypoplasia as the predominant manifestations, while no sign of nystagmus was detected
Summary
GPR143, known as the ocular albinism type 1 (OA1) gene, encodes a 7TM G-protein coupled protein and is exclusively expressed by pigment cells. The mutation of GPR143 leaded to OA1, an X-linked type of albinism, which results in nystagmus, impaired visual acuity and foveal hypoplasia [1]. The form of albinism in OA1 patients affects the eye, especially iris and fundus, but the pigmentation of hair and skin is usually normal. We reported and characterized a large Chinese family, in which all the affected individuals are afflicted with poor visual acuity and foveal hypoplasia as the predominant manifestations, while no sign of nystagmus was detected. Our results presented this previously unidentified mutation of GPR143 that caused the isolated foveal hypoplasia without nystagmus. Fundus autofluorescence imaging (AFI) revealed the reduced area of blocked fluorescence at foveal region, indicating the macular pigment was severely affected (Fig. 1B). ID# Patient/Carrier Gender Age Mutation Foveal hypoplasia Fundus hypopigmentation Nystagmus Iris hypopigmentation
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