{Reference Type}: Case Reports
{Title}: Case report: novel PCDH15 variant causes usher syndrome type 1F with congenital hearing loss and syndromic retinitis pigmentosa.
{Author}: Chen N;Lee H;Kim AH;Liu PK;Kang EY;Tseng YJ;Seo GH;Khang R;Liu L;Chen KJ;Wu WC;Hsiao MC;Wang NK;
{Journal}: BMC Ophthalmol
{Volume}: 22
{Issue}: 1
{Year}: Nov 2022 16
{Factor}: 2.086
{DOI}: 10.1186/s12886-022-02659-6
{Abstract}: <B>BACKGROUND: </B>Usher syndrome (USH) is an autosomal recessive disorder primarily responsible for deaf-blindness. Patients with subtype Usher syndrome type 1 (USH1) typically experience congenital sensorineural hearing loss, abnormal vestibular function, and retinitis pigmentosa (RP). Here we present a case of Usher syndrome type 1F (USH1F) with a novel homozygous variant in the calcium-dependent cell-cell adhesion protocadherin-15 (PCDH15) gene.<BR><B>METHODS: </B>Ophthalmic examinations were evaluated over a course of 10 years and the disease-causing variant was identified by whole exome sequencing (WES). Initial and follow-up examination of color fundus photos after 10 years revealed an increase in bone spicule pigment deposits in both eyes. A parafoveal hyper-AF ring in both eyes was shown in fundus autofluorescence (FAF) with a progressive diameter-wise constriction observed over 8 years. Outer nuclear layer (ONL) loss was observed in parafoveal and perifoveal regions of both eyes on spectral domain-optical coherence tomography (SD-OCT). Full-field electroretinography (ffERG) showed extinguished global retinal function. WES identified a novel two-base-pair deletion, c.60_61del (p.Phe21Ter), in the PCDH15 gene, confirming the diagnosis of USH1F.<BR><B>CONCLUSIONS: </B>We report a novel homozygous PCDH15 pathogenic variant expected to lead to nonsense-mediated decay (NMD) of PCDH15 mRNA. The patient exhibits a loss of function with USH1F, experiencing congenital hearing loss and syndromic RP.