New mutations identified in the ocular albinism type 1 gene

Deep intronic GPR143 mutation in a Japanese family with ocular albinism

Deep intronic mutations are often ignored as possible causes of human disease. Using whole-exome sequencing, we analysed genomic DNAs of a Japanese family with two male siblings affected by ocular albinism and congenital nystagmus. Although mutations or copy number alterations of coding regions were not identified in candidate genes, the novel intronic mutation c.659-131 T > G within GPR143 intron 5 was identified as hemizygous in affected siblings and as heterozygous in the unaffected mother. This mutation was predicted to create a cryptic splice donor site within intron 5 and activate a cryptic acceptor site at 41nt upstream, causing the insertion into the coding sequence of an out-of-frame 41-bp pseudoexon with a premature stop codon in the aberrant transcript, which was confirmed by minigene experiments. This result expands the mutational spectrum of GPR143 and suggests the utility of next-generation sequencing integrated with in silico and experimental analyses for improving the molecular diagnosis of this disease.

An integrated approach to uncover drivers of cancer

Systematic characterization of cancer genomes has revealed a staggering number of diverse aberrations that differ among individuals, such that the functional importance and physiological impact of most tumor genetic alterations remain poorly defined. We developed a computational framework that integrates chromosomal copy number and gene expression data for detecting aberrations that promote cancer progression. We demonstrate the utility of this framework using a melanoma data set. Our analysis correctly identified known drivers of melanoma and predicted multiple tumor dependencies. Two dependencies, TBC1D16 and RAB27A, confirmed empirically, suggest that abnormal regulation of protein trafficking contributes to proliferation in melanoma. Together, these results demonstrate the ability of integrative Bayesian approaches to identify candidate drivers with biological, and possibly therapeutic, importance in cancer.

Identification of a novel mutation in a Chinese family with X-linked ocular albinism

PURPOSE

The purpose of the study was to evaluate the GPR143 gene (G-protein coupled receptor 143) in a Chinese three-generation family with OA1, including four carriers and a proband with clinical features of X-linked ocular albinism.

METHODS

The proband underwent a detailed ophthalmologic evaluation. Blood samples of family members were obtained and genomic DNA isolated. Mutational analysis by SSCP and direct sequencing of the GPR143 gene was used to screen all nine exons including the intron/exon junctions. The novel mutation c.943G>T (p.G315X) found in the study was confirmed by DHPLC to exclude the possibility of polymorphism.

RESULTS

Ophthalmic features of the proband were characteristic of X-linked ocular albinism. The authors identified a novel nonsense mutation p.G315X on exon 8 that was not found in 100 non-albinism subjects by DHPLC. This novel mutation in the GPR143 gene is predicted to subject to nonsense mediated decay.

CONCLUSIONS

The novel mutation p.G315X in the OA1 gene was identified in a Chinese family with ocular albinism, which is predicted to generate a premature stop codon. These findings extend the mutational spectrum of GPR143 gene and will be useful for gene diagnosis and genetic counseling in Chinese OA1 patients.