Screening for <i>SLC7A14</i> gene mutations in patients with autosomal recessive or sporadic retinitis pigmentosa

<p><i>Purpose</i>: In this study, we aimed to detect mutations in the <i>SLC7A14</i> cationic transporter gene, which has recently been reported as a causative gene for retinitis pigmentosa (RP), in Japanese patients with autosomal recessive (AR) or sporadic RP.</p> <p><i>Materials and Methods</i>: We included 146 unrelated Japanese patients with AR or sporadic RP who lacked mutations in genes known to be associated with RP despite next-generation sequencing-based screening. We sequenced the seven <i>SLC7A14</i> coding exons along with their flanking intronic DNA using the Sanger method. The detected polymorphisms were assessed for their pathogenicity with <i>in silico</i> prediction tools. For those who had heterozygous, nonsynonymous variants, we performed multiplex ligation-dependent probe amplification (MLPA) to search for additional deletion/duplication.</p> <p><i>Results</i>: We detected four distinct <i>SLC7A14</i> polymorphisms excluding synonymous polymorphisms. Two of these polymorphisms were assessed as detrimental by <i>in silico</i> prediction tools. However, all of the mutations were heterozygous. Neither homozygous polymorphisms nor compound heterozygous polymorphisms, which are considered detrimental variants, were detected. Neither deletion nor duplication was found with MLPA in patients with heterozygous variants.</p> <p><i>Conclusions</i>: The four <i>SLC7A14</i> mutations detected herein were unlikely to be pathogenic in this Japanese cohort. The frequency and pathogenicity of <i>SLC7A14</i> mutations may vary depending on ethnicity, and these mutations may be rare in Japanese patients.</p

Image of correspondence between fundus shape, curvature, and color.

<p><b>A,</b> An imaginary Bruch’s membrane line to exemplify the correspondence. The curvature of one point was measured using 3 sequential A-scans (500-µm apart) so that it represented local shape in the range of 1,000-µm (Local curvature). Five points are exemplified in this figure. <b>B,</b> Corresponding curvature [1/µm] and color image for each 5 point. Positive, negative, or zero value of the curvature κ represents upward concave, downward convex, or flat, respectively. The color of curvature map showed a gradient from green (RGB(0, 192, 32)) to yellow (RGB(255, 255, 0)) as a local curvature value changes from 0.0005 to 0.0, and a gradient from red (RGB(255, 0, 0)) to yellow (RGB(255, 255, 0)) as a local curvature value changes from −0.0005 to 0.0.</p

Mean variance of curvature for eyes with each complication.

<p>P-values* are shown.</p><p>*Tukey-Kramer’s multiple comparison.</p><p>CNV: choroidal neovascularization, RD: retinal detachment, CRA: chorioretinal atrophy.</p><p>Mean variance of curvature for eyes with each complication.</p

Characteristics of the included eyes according to the presence of staphylomas.

<p>*unpaired <i>t</i>-test.</p>†<p>Fisher’s exact test.</p><p>Characteristics of the included eyes according to the presence of staphylomas.</p

Representative color maps of highly myopic eyes.

<p><b>A,</b> Right eye from a 58-year-old woman with axial length of 29.01 mm. The staphyloma edge is depicted in green-yellow. <b>B,</b> Right eye of a 72-year-old woman with axial length of 28.37 mm. Upper and lower edges of the staphyloma can be visualized clearly. <b>C,</b> Right eye of a 38-year-old woman, with axial length of 26.38 mm. The yellow-dominant color map represents a relatively flat fundus. <b>D,</b> Right eye from a 65-year-old woman with axial length of 34.64 mm. The mosaic color pattern indicates an undulated fundus.</p

Scatter plot assigning mean curvature to the horizontal axis and variance of curvature to the vertical axis.

<p><b>A,</b> All 182 highly myopic eyes are plotted. <b>B,</b> 33 eyes with myopic choroidal neovascularization (mCNV) are highlighted. Most values localize to the lower segment of the splitting line at 0.00015 for mean curvature and 1×10⁻⁸ for variance of curvature. <b>C,</b> 17 eyes with severe chorioretinal atrophy (CRA) are highlighted. Most of these values localize to the higher segment of the splitting line. <b>D,</b> 33 eyes with retinoschisis (open circles) and 11 eyes with foveal retinal detachments (filled circles) are plotted. <b>E,</b> Eyes with and without staphylomas. The groups are easily separated into 2 groups by broken lines that indicate 0.000078 in mean curvature and 0.26×10⁻⁸ in curvature variance. One eye without a staphyloma had focal choroidal excavation (square).</p

Mean absolute curvature of eyes with each complication.

<p>P-values* are shown.</p><p>*Tukey-Kramer’s multiple comparison.</p><p>CNV: choroidal neovascularization, RD: retinal detachment, CRA: chorioretinal atrophy.</p><p>Mean absolute curvature of eyes with each complication.</p

Construction of the curvature map for a normal eye.

<p><b>A,</b> Bruch’s membrane was plotted in each of 12 radial OCT scans with the fovea at the center. Local curvature was measured from 3 sequential points (sampled at 500-µm intervals). The sine of curvature was defined as positive when the membrane was convex upward. <b>B,</b> The value of curvature was mapped using yellow (RGB(255, 255, 0)) to represent zero curvature (flat), green (gradient from RGB(255, 255, 0) to RGB(0, 192, 32) according to curvature [1/µm]) for positive curvature (convex-upward), and red (gradient from RGB(255, 255, 0) to RGB(255, 0, 0) according to curvature [1/µm]) for negative curvature (convex-downward). <b>C,</b> Color fundus photograph on which the topographic maps will be overlaid. <b>D,</b> Scanning Laser Ophthalmoscope (SLO) images are overlaid on the fundus photographs. <b>E,</b> Topographic maps are overlaid on the SLO images. <b>F and G,</b> SLO image transparency was increased for an accurate superimposition.</p

Comparison of Optic Disc Morphology of Optic Nerve Atrophy between Compressive Optic Neuropathy and Glaucomatous Optic Neuropathy

<div><p>Objectives</p><p>To compare the optic nerve head (ONH) structure between compressive optic neuropathy (CON) and glaucomatous optic neuropathy (GON), and to determine whether selected ONH quantitative parameters effectively discriminate between GON and CON, especially CON cases presenting with a glaucoma-like disc.</p><p>Methods</p><p>We prospectively assessed 34 patients with CON, 34 age-matched patients with moderate or severe GON, and 34 age-matched healthy control subjects. The quantitative parameters of ONH structure were compared using the Heidelberg Retina Tomograph 2 (HRT2) and Spectralis optical coherence tomography with an enhanced depth imaging method.</p><p>Results</p><p>The mean and maximum cup depths of CON were significantly smaller than those with GON (<i>P</i><0.001 and <i>P</i><0.001, respectively). The distance between Bruch's membrane opening and anterior surface of the lamina cribrosa (BMO-anterior LC) of CON was also significantly smaller than that of glaucoma but was similar to that of the healthy group (<i>P</i><0.001 and <i>P</i> = 0.47, respectively). Based on Moorfields regression analysis of the glaucoma classification of HRT2, 15 eyes with CON were classified with a glaucoma-like disc. The cup/disc area ratio did not differ between cases of CON with a glaucoma-like disc and cases of GON (<i>P</i> = 0.16), but the BMO-anterior LC and mean and maximum cup depths of CON cases with a glaucoma-like disc were smaller than those in GON (<i>P</i> = 0.005, <i>P</i> = 0.003, and <i>P</i> = 0.001, respectively).</p><p>Conclusions</p><p>Measurements of the cup depths and the LC depth had good ability to differentiate between CON with a glaucoma-like disc and glaucoma. There was no laminar remodeling detected by laminar surface position in the patients with CON compared to those with GON.</p></div

Comparison of OCT and HRT parameters between eyes with CON with a glaucoma-like disc and eyes with glaucoma.

<p>CON =  compressive optic neuropathy; OCT =  optical coherence tomography; HRT =  Heidelberg Retina Tomograph; BMO-anterior LC =  distance between Bruch's membrane opening and anterior surface of lamina cribrosa.</p><p>Comparison of OCT and HRT parameters between eyes with CON with a glaucoma-like disc and eyes with glaucoma.</p