GPR98 mutations cause Usher syndrome type 2 in males.

Mutations in the large GPR98 gene underlie Usher syndrome type 2C (USH2C), and all patients described to date have been female. It was speculated that GPR98 mutations cause a more severe, and eventually lethal, phenotype in males. We describe for the first time two male patients with USH2 with novel GPR98 mutations. Clinical characterization of a male patient and his affected sister revealed a typical USH2 phenotype in both. GPR98 may have been excluded from systematic investigation in previous studies, and the proportion of patients with USH2C probably underestimated. GPR98 should be considered in patients with USH2 of both sexes.

Characterisation of severe rod-cone dystrophy in a consanguineous family with a splice site mutation in the MERTK gene.

AIM: To characterise the ocular phenotype of a family segregating the splice site mutation c.2189+1G>T in the tyrosine kinase receptor gene MERTK. METHODS: Five affected children of a consanguineous Moroccan family were investigated by ophthalmic examinations, including fundus photography, autofluorescence (FAF) imaging, optical coherence tomography (OCT), psychophysical and electrophysiological methods. RESULTS: Affected children were between 5 and 19 years of age, allowing an estimation of disease progression. Electroretinography demonstrated loss of scotopic and photopic function in the first decade of life. Younger siblings showed drusen-like deposits with focal relatively increased FAF in the macular area. With increasing age, a yellowish lesion with relatively increased FAF and subsequent macular atrophy developed. Visual acuity deteriorated with age and ranged between 20/50 in the best eye of the youngest affected and 20/400 in the worst eye of the oldest affected sibling. Spectral-domain OCT revealed debris-like material in the subneurosensory space. CONCLUSION: The splice site mutation c.2189+1G>T in MERTK causes rod-cone dystrophy with a distinct macular phenotype. The debris in the subneurosensory space resembles that in the Royal College of Surgeons (RCS) rat being the mertk animal model. Patients might therefore benefit from advances in gene therapy that were previously achieved in the RCS rat.