General information
The SALSA MLPA
Probemix P262 GHI is a
research use only (RUO) assay for the detection of deletions or duplications in the
GHR,
JAK2,
IGF1, and
STAT5B genes, which are associated with growth hormone insensitivity (GHI).
GHI is characterized by severe short stature, normal to elevated serum levels of growth hormone (GH) and resistance to exogenous GH therapy. The aetiology of GHI is classically associated with mutations in the GH receptor (
GHR) gene or with mutations affecting the signalling cascade of the
GHR (OMIM 245590). Intracellular signalling molecules activated by GH belong to the Janus kinase-signal transducer and activator of transcription 5B (
JAK2-
STAT5B) pathway. Amongst others, this pathway activates the insulin-like growth factor (
IGF1), which is implicated in the regulation of protein turnover and exerts potent mitogenic and differentiating effects on most cell types.
There are two genomic isoforms of the
GHR gene in humans: a full-length isoform (GHRfl) and an isoform lacking exon 3 (GHRd3). The distribution of these genotypes differs among populations, with the frequency for GHRfl/GHRfl ranging from 35-53%, for GHRfl/GHRd3 between 33-58%, and for GHRd3/GHRd3 ranging from 7-26%. Growth hormone is used to increase height in short children who are not deficient in growth hormone receptor, but its efficacy varies widely between individuals. Dos Santos et al. (2004, Nat Genet.) found that the GHRd3 isoform was associated with 1.7 to 2 times more growth acceleration induced by growth hormone than the full-length isoform.
This SALSA MLPA probemix is not CE/FDA registered for use in diagnostic procedures. Purchase of this product includes a limited license for research purposes.
Probemix content
The SALSA MLPA Probemix P262-B2 GHI contains 50 MLPA probes with amplification products between 130 and 494 nucleotides (nt). This includes 11 probes for the
GHR gene, one probe for each exon and two probes for exon 10, 15 probes for the
JAK2 gene for 15 different exons, four probes for the
IGF1 gene, and 11 for the
STAT5B gene. In addition, nine 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.