General information
The SALSA MLPA Probemix P179 Limb malformations-1 is a research use only (RUO) assay for the detection of deletions or duplications in the GLI3, HOXD13, and ROR2 genes, which are associated with limb malformations, including Greig cephalopolysyndactyly syndrome, Pallister-Hall syndrome and Robinow syndrome.

The GLI3 gene encodes a protein that belongs to the C2H2-type zinc finger proteins. Defects in the GLI3 gene cause a wide variety of phenotypes, including Greig cephalopolysyndactyly syndrome (GCPS) and Pallister-Hall syndrome.

The HOXD13 gene encodes a transcription factor and is involved in distal limb patterning. Four types of HOXD13 mutations are associated with distinct phenotypes. Expansions in the amino-terminal polyalanine tract cause synpolydactyly (SPD), specific missense mutations cause brachydactyly type E, intragenic deletions or other missense mutations cause SPD with an additional foot phenotype, while a splice site mutation has been reported to cause only foot malformation.

The ROR2 gene encodes a transmembrane receptor tyrosine kinase, which is particularly important for the chondrocyte lineage. Mutations in ROR2 have been shown to result in brachydactyly type B, and in autosomal recessive Robinow syndrome.

Probemix content
The SALSA MLPA Probemix P179-B1 Limb malformations-1 contains 43 MLPA probes with amplification products between 130 and 463 nucleotides (nt). This includes 21 probes for the GLI3 gene, at least one probe for each exon, two probes for the HOXD13 gene, and ten probes for the ROR2 gene, one probe for each exon and two probes for exon 1. In addition, ten reference probes are included that detect autosomal chromosomal locations. 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.