General Information: The SALSA MLPA Probemix P351 PKD1 and P352 PKD1-PKD2 is a
research use only (RUO) assay for the detection of deletions or duplications in
PKD1 and
PKD2, which are associated with Autosomal Dominant Polycystic Kidney Disease (ADPKD).
ADPKD is an autosomal disorder, which is characterized by bilateral renal cysts, liver cysts and intracranial aneurysms. Fifty percent of ADPKD patients develop end stage renal disease at the age of 60, where patients with a
PKD1 mutation show a more progressive renal phenotype compared to patients with
PKD2 mutations (Choi et al. 2014). Although all individuals with ADPKD develop cysts within the kidneys, there is substantial variability in severity of renal disease and other manifestations of the disease, even within the same family.
Approximately 85% of patients with ADPKD have pathogenic variants in
PKD1, whereas approximately 15% have pathogenic variants in
PKD2. DNA analysis of the PKD1 gene is complicated due to the presence of several
PKD1 pseudogenes on 16p13.11 at 16 Mb from the p-telomere. The
PKD1 product, polycystin-1, is a membrane-associated protein, though its exact function is not exactly known. It is thought to play a role in the polycystin complex, by regulating the polycystin-2 calcium channel, which is encoded by
PKD2. Both proteins are also present in primary cilia. Mutations in either
PKD1 or
PKD2 likely disrupt the protein interaction and alter signalling within the cell and in primary cilia, causing cysts. Around 2-4% of
PKD1/
PKD2 mutations are single- and multi-exon deletions and/or duplications (Carrera et al. 2016, Choi et al. 2014, Obeidova et al. 2014).
More information is available at
https://www.ncbi.nlm.nih.gov/books/NBK1246/.
Probemix content: The SALSA MLPA Probemixes P351-C1 PKD1 and P352-D1 PKD1-PKD2 contain 27 and 13 probes for
PKD1, respectively. Together, these probemixes cover 36 of the 46 exons of
PKD1. There are two probes upstream of
PKD1, 3 probes for exon 15 of
PKD1 and 3 probes for the flanking gene
TSC2, located just downstream of
PKD1. In addition, P352-D1 includes 17 probes covering all
PKD2 exons with the exception of exon 13. There are two probes present for exon 1, 2 and 6.
The P351-C1 probemix contains 41 MLPA probes with amplification products between 135 and 459 nt, which includes 11 reference probes detecting 11 different autosomal chromosomal locations. The P352-D1 probemix contains 41 MLPA probes with amplifications products between 136 and 471 nt, of which 11 are reference probes detecting 11 different autosomal chromosomal locations. Complete probe sequences and the identity of the genes detected by the reference probes is available online (
www.mlpa.com).
These probemixes contain 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.mlpa.com.