General information
The SALSA MLPA Probemix P429 SDHA-MAX-TMEM127 is a research use only (RUO) assay for the detection of deletions or duplications in the SDHA, MAX and TMEM127 genes, which are associated with pheochromocytomas (PCCs) and paragangliomas (PGLs).

PCCs and PGLs are highly vascular, catecholamine-secreting tumours derived from chromaffin cells in the adrenal medulla (PCCs) and from extra-adrenal neural crest progenitors (PGLs). Although PCCs and PGLs are predominantly benign, 10-15% can develop metastases (Jimenez et al. 2013). Up to 40% of the PCC and PCL patients carry a germline mutation in one of the at least 12 genes, among them are the SDHA, MAX and TMEM127 genes (Gimenez-Roqueplo et al. 2012; Neumannn et al. 2002). Eight out of the remaining susceptibility genes - VHL, SDHB, SDHC, SDHD, NF1, RET and HRAS - are included in other available SALSA MLPA Probemixes (see Related SALSA MLPA Probemixes on page 9 of the product description).

Mutations in the succinate dehydrogenase complex subunit gene A (SDHA), at 5p13.33, can lead to PCC and PGL with variable penetrance (Burnichon et al. 2010). Moreover, bi-allelic SDHA mutations have been shown to cause an early onset neurodegenerative disorder known as Leigh syndrome (Hovarth et al. 2006).

Germline mutations in myc-associated factor X (MAX), at 14q23.2, have been shown to be responsible for ~1% of PCC/PGL patients (Comino-Mendez et al. 2011; Burnichon et al. 2012). The MAX transcription factor is a member of basic helix-loop-helix leucine zipper (bHLHZ) family of transcription factors. Through the ability of MAX to form homo- or heterodimers with other family members, like MYC and MAD, the MAX gene is suggested to act as a tumour suppressor gene and to play an important role in cell proliferation, differentiation and apoptosis (for review see Dang 2012; Cascon and Robledo 2012). Recently, both germline and somatic intragenic copy number alterations of MAX gene have been described (Korpershoek et al. 2016; Daly et al. 2018).

Truncating or missense germline mutations in transmembrane protein 127 (TMEM127), at 2q11.2, have been identified in PCC patients. Truncating or missense TMEM127 mutations can lead to inactivation of the mTOR1 protein kinase (Qin et al. 2014) that regulates cell growth, cell proliferation, cell motility, cell survival, protein synthesis, autophagy and transcription (Lipton and Sahin 2014). Although pathways via which TMEM127 acts are yet to be further elucidated, research has shown that the TMEM127 protein is a component of the mTORC1 lysosomal nutrient-sensing complex (Deng et al. 2018).

More information is available at https://www.ncbi.nlm.nih.gov/books/NBK1548/

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 P429-C1 SDHA-MAX-TMEM127 contains 45 MLPA probes with amplification products between 124 and 500 nucleotides (nt). This includes 12 probes for the SDHA gene, one probe targeting a region located upstream and two probes targeting a region located downstream of the SDHA gene; eight probes for the MAX gene, two probes targeting a region located upstream and two probes targeting a region located downstream of the MAX gene; four probes for the TMEM127 gene, one probe targeting a region located upstream and one probe targeting a region downstream of the TMEM127 gene. In addition, 12 reference probes are included that target relatively copy number stable regions in various cancer types including PCC and PGL. Complete probe sequences and the identity of the genes detected by the reference probes are available in table 3 and 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.