Molecular Diagnosis of Putative Stargardt Disease by Capture Next Generation Sequencing

<div><p>Stargardt Disease (STGD) is the commonest genetic form of juvenile or early adult onset macular degeneration, which is a genetically heterogeneous disease. Molecular diagnosis of STGD remains a challenge in a significant proportion of cases. To address this, seven patients from five putative STGD families were recruited. We performed capture next generation sequencing (CNGS) of the probands and searched for potentially disease-causing genetic variants in previously identified retinal or macular dystrophy genes. Seven disease-causing mutations in <i>ABCA4</i> and two in <i>PROM1</i> were identified by CNGS, which provides a confident genetic diagnosis in these five families. We also provided a genetic basis to explain the differences among putative STGD due to various mutations in different genes. Meanwhile, we show for the first time that compound heterozygous mutations in <i>PROM1</i> gene could cause cone-rod dystrophy. Our findings support the enormous potential of CNGS in putative STGD molecular diagnosis.</p></div

DNA sequence chromatograms.

<p>DNA sequence chromatograms of the affected members with putative Stargardt disease. The heterozygous peaks of the mutations were pointed out by red arrow. The origin of each mutation was being traced from paternal or maternal allele.</p

Mean coverage of Capture Next Generation Sequencing.

<p>A mean coverage of 200× over the targeted region was achieved; part of the sequencing region was showed.</p

<i>PROM1</i> gene mutations and diseases.

<p>R/D: Recessive and Dominant; STGD, Stargardt Disease; MCDR,Macular Dystrophy; CRD, Cone-Rod Dystrophy;</p><p>RP, Retinitis Pigmentosa; N/A, No Answer;</p><p>*originally as c.1878del G.</p

Color Fundus photographs of the patients.

<p>Color fundus photograph of patient II:1 from family B and patients II:1 from family E. Both of them showed macular atrophy.</p

Clinical summaries of individuals in this study.

<p>M,Male; F,Female; BCVA, Best corrected visual acuity; N/A*, No Answer; +*, Affected.</p

Electroretinogram and OCT testing of the patient from family E.

<p>A. The electroretinogram (ERG) showed cone responses are more severely affected than rod responses (Only B wave has a small peak at 108 ms/56.6uv). This is the key clinical characteristics for diagnosis of CRD. B. OCT (Optical Coherence Tomography) testing of the patient from family E showed that photoreceptor segments and the retinal pigment epithelium were seriously affected.</p