General information
The SALSA MLPA Probemix P488 RS1 is a research use only (RUO) assay for the detection of deletions or duplications in the RS1 gene, which is associated with X-linked juvenile retinoschisis.

X-linked juvenile retinoschisis is a retinal dystrophy that leads to schisis (splitting) of the neural retina leading to reduced visual acuity in affected men. The split in the retina occurs predominantly within the inner retinal layers and is very different from retinal detachment, which is a split between the neural retina and the retinal pigment epithelium. This condition is caused by defects in the RS1 gene that lead to a dysfunctional retinoschisin protein which causes impaired adhesion of retinal cells. The prevalence of X-linked juvenile retinoschisis is estimated between 1 in 15,000 and 1 in 30,000 (Sikkink et al. 2007).

The RS1 gene (6 exons) spans ~32.4 kb of genomic DNA and is located on Xp22.13, 18.6 Mb from the p-telomere. The CDKL5 gene partially overlaps with RS1, having exons flanking RS1 and exons within introns of RS1 (see Figure 1 in the product description). This SALSA MLPA Probemix contains probes for both RS1 and CDKL5.

Probemix content
The SALSA MLPA Probemix P488-B1 RS1 contains 19 MLPA probes with amplification products between 157 and 298 nucleotides (nt). This includes six probes for the RS1 gene (one probe for each exon of the gene), and four probes for the CDKL5 gene. In addition, nine reference probes are included that detect other locations on the X-chromosome. The probes targeting CDKL5 could be informative on the size of the deletion or duplication. Complete probe sequences and the identity of the genes detected by the reference probes are available online (www.mrcholland.com).

This probemix contains nine quality control fragments generating amplification products between 64 and 105 nt: four DNA Quantity fragments (Q-fragments), two DNA Denaturation fragments (D-fragments), one Benchmark fragment, and one chromosome X and one chromosome Y-specific fragment. More information on how to interpret observations on these control fragments can be found in the MLPA General Protocol and online at www.mrcholland.com.