Mutations in the G protein‐coupled receptor 143 (GPR143) gene were determined by DNA sequencing assays and poly‐ merase chain reaction assays for deletions; all exon coding sequences, exons at the 5'‐ and 3'‐ends, and non‐coding region

Ocular albinism type 1 (OA1) is a genetic disorder characterized by reduced eye pigmentation and nystagmus, which is often accompanied by decreased visual acuity, strabismus and other symptoms, whereas skin and hair color remain normal. The present study aimed to assess the clinical features and perform genotype analysis of a family with OA1, and to determine the disease‐causing mutation. A total of 18 family members (nine affected patients and nine normal subjects) from Hainan, China, were recruited to the present study in December 2017. A detailed clinical ophthalmic examination was performed for all participants, including a visual acuity test, anterior segment slit lamp examination, eye fundus examination and optical coherence tomography. Mutations in the G protein‐coupled receptor 143 (GPR143) gene were determined by DNA sequencing assays and poly‐ merase chain reaction assays for deletions; all exon coding sequences, exons at the 5'‐ and 3'‐ends, and non‐coding region sequences of intron splicing were assessed. Within the family, nine male patients exhibited disease occurrence at the age of 0‐6 months. All patients presented with different degrees of iris depigmentation, horizontal jerk nystagmus, foveal hypoplasia and reduced visual acuity. The fundus of only one patient exhibited choroid coloboma; in the remaining patients, their fundi exhibited different degrees of irregular retinal depigmentation. The mutation c.360+5G>T in the GPR143 gene was identified in this family. In conclusion, the present study identified the splicing mutation c.360+5G>T in the GPR143 gene in a Chinese family with OA1 and successfully identified the site. To the best of our knowledge, there have been no previous reports regarding this mutation in any major genome databases; therefore, this outcome may enrich the mutation spectrum of the GPR143 gene. Introduction Albinism is a rare hereditary disease associated with an absence of pigment in the eyes, skin and hair, due to congenital defects in melanocytes. Oculocutaneous albinism and ocular albinism type 1 (OA1) are the two main subtypes of albinism. The birth prevalence of OA1 is ~1 in 60,000 (1); however, reports on Chinese patients with OA1 are rare and epidemiological data are lacking. Compared with other types of albinism, patients with OA1 appear to be almost exclusively males and present with only ocular abnormalities. OA1 is characterized by varying degrees of iris depigmentation, nystagmus, loss of stereoscopic vision, foveal hypoplasia, fundus hypopigmenta‐ tion and reduced visual acuity (2‐6). Female carriers do not exhibit clinical symptoms but have spotty or patchy pigment loss in the fundus, which is also considered a characteristic of OA1 (7). OA1 has a Mendelian inheritance pattern and the G protein‐coupled receptor 143 gene (GPR143; OMIM: #300808, NCBI gene ID: 4935) has been identified as the disease‐causing gene. The GPR143 gene, which has also been reported to cause congenital nystagmus, possesses nine exons and spans ~40 kb of genomic DNA (8). GPR143 encodes proteins that are impor‐ tant for the development and maturation of melanosomes, and is only localized in the lysosomes and melanosomes of cells (9). A previous study reported that OA1 is a disorder involving protein misfolding as a pathogenic mechanism, rather than the lack of melanin synthesis (10). The typical clinical features of OA1 are iris and fundus depigmentation, nystagmus, foveal hypoplasia, and normally pigmented skin and hair. In addition, OA1 is often associated with reduced visual acuity. Since iris or fundus depigmentation are very slight and insidious among Asian patients with OA1, it can easily be misdi‐ agnosed as other congenital eye diseases, such as congenital idiopathic nystagmus (CIN), although the treatment principle for OA1 and CIN is the same (11‐16). Molecular diagnosis combined with detailed eye examinations, including optical coherence tomography (OCT) and detailed slit lamp examina‐ tion, are effective tools for differential diagnosis (17‐20). In the present study, the clinical manifestations were described and a molecular genetic analysis was performed on a Chinese family with X‐linked OA1. Reports of X‐linked OA1 in Asian populations are relatively rare (7‐16); therefore, the present results may enrich the mutation spectrum of GPR143 in the Asian population. A novel GPR143 mutation in a Chinese family with X‐linked ocular albinism type 1 XUHUI GAO, TIECHENG LIU, XUAN CHENG, AIAI DAI, WEI LIU, RUNPU LI and MAONIAN ZHANG Department of Ophthalmology, Chinese PLA General Hospital, Beijing 100853, P.R. China Received March 27, 2019; Accepted September 19, 2019 DOI: 10.3892/mmr.2019. 10813 Correspondence to: Professor Tiecheng Liu, Department of Ophthalmology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, P.R. China E‐mail: ltc301@sina.com