General information
The SALSA MLPA
Probemix P220 Obesity is a
research use only (RUO) assay for the detection of deletions or duplications in the
LEPR,
POMC,
SIM1,
LEP,
MC4R,
MC2R and
MC3R genes and the 16p11.2 region, which are associated with obesity.
Obesity is known to have a genetic basis and is often accompanied by hyperglycemia, hypertension and hyperlipidemia. Leptin deficiency, leptin receptor deficiency, and proopiomelanocortin deficiency, all involved in obesity, can be inherited in an autosomal recessive fashion. Leptin (encoded by
LEP) is an adipocyte-specific hormone which plays a major role in the regulation of body weight. Leptin acts through the leptin receptor (
LEPR), a single-transmembrane-domain receptor of the cytokine receptor family, which is found in many tissues in several alternatively spliced forms. The proopiomelanocortin (
POMC) gene encodes a polypeptide hormone precursor that undergoes extensive, tissue-specific, post-translational processing via cleavage by subtilisin-like enzymes known as prohormone convertases.
The
LEPR gene (23 exons) spans ~215 kb of genomic DNA and is located on 1p31.3, ~66 Mb from the p-telomere. The
POMC gene (4 exons) spans ~8.0 kb of genomic DNA and is located on chromosome 2p23.3, ~25 Mb from the p-telomere. The
LEP gene (3 exons) spans ~16 kb of genomic DNA and is located on chromosome 7q32.1, ~128 Mb from the p-telomere.
Obesity can also be caused by mutations in single-minded homolog 1 (
SIM1; Holder et al. 2000), the melanocortin-4 receptor gene (
MC4R; Emmerson et al. 2007),
MC3R (Tao and Segaloff 2004) and
MC2R. MC4R deficiency is the most common form of monogenic obesity (Faroogi et al. 2003).
The
SIM1 gene (11 exons) spans ~80 kb of genomic DNA and is located on chromosome 6q16.3, ~101 Mb from the p-telomere. The
MC4R gene (1 exon) spans ~1.7 kb of genomic DNA and is located on chromosome 18q21.32, ~56 Mb from the p-telomere. The
MC2R gene (2 exons) spans ~33 kb of genomic DNA and is located on chromosome 18p11.21, ~14 Mb from the p-telomere. The
MC3R gene (1 exon) spans ~1.1 kb of genomic DNA and is located on chromosome 20q13.2, ~54 Mb from the p-telomere.
Deletions of chromosome 16p11.2 are also found to be associated with obesity (Bochukova et al. 2010). The 16p11.2 region harbours
SH2B1, involved in leptin and insulin signalling. Aside from
SH2B1, the whole 16p11.2 region (including
SEZ6L2) is associated with obesity.
The
SH2B1 gene (10 exons) spans ~10 kb of genomic DNA and is located on chromosome 16p11.2, ~29 Mb from the p-telomere. The
SEZ6L2 gene (18 exons) spans ~28 kb of genomic DNA and is located on chromosome 16p11.2, ~30 Mb from the p-telomere.
More information is available at
https://www.ncbi.nlm.nih.gov/books/NBK11167/ (16p11.2 recurrent deletion).
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 P220-B3 Obesity contains 47 MLPA probes with amplification products between 130 and 495 nucleotides (nt). This includes 11 probes for
LEPR, four probes for
POMC, eight probes for
SIM1, four probes for genes flanking
SIM1, three probes for
LEP, four probes for the 16p11.2 region, two probes for
MC4R, one probe for
MC2R, and two probes for
MC3R. In addition, eight 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.