General information: The SALSA MLPA
Probemix P283 TPMT is a
research use only (RUO) assay for the detection of deletions or duplications in the
TPMT gene, which is associated with thiopurine S-methyltransferase deficiency (TPMT deficiency). This probemix can also be used to detect the presence of the c.460A>G/p.A154T (TPMT*3B allele), c.719A>G/p.Y240C (TPMT*3C allele), or both (TPMT*3A allele), and c.238G>C/p.A80P (TPMT*2 allele) point mutations.
Defects in the thiopurine S-methyltransferase (
TPMT) gene are the cause of TPMT deficiency. TPMT is an enzyme involved in the normal metabolic inactivation of thiopurine drugs. These drugs are generally used as immunosuppressant or cytotoxic drugs and are prescribed for a variety of clinical conditions including leukaemia, autoimmune disease, and organ transplantation. Patients with intermediate or no
TPMT activity are at risk of toxicity after receiving standard doses of thiopurine drugs and it is shown that inter-individual differences in response to these drugs are largely determined by genetic variation at the
TPMT locus.
Probemix content: The SALSA MLPA Probemix P283-B2 TPMT contains 22 MLPA probes with amplification products between 130 and 380 nucleotides (nt). This includes nine probes for the
TPMT gene, one probe for each of the nine exons, with the exception of exon 6, and two probes for exon 2. In addition, this probemix contains probes specific for the A154T and A80P mutations, which will only generate a signal when the mutations are present, and one probe detecting the wildtype sequence of the Y240C mutation, a reduced signal can point towards the presence of this mutation
or a deletion of exon 9. 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.mlpa.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, 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.
SALSA Binning DNA SD087: The SD087 Binning DNA provided with this probemix can be used for binning of two mutation-specific probes (314 nt probe 17379-SP0499-L22511 A154T mutation and 277 nt probe 17378-SP0500-L22512 A80P mutation). SD087 Binning DNA is a mixture of genomic DNA from healthy individuals and synthetic DNA that contains the target sequence detected by the above mentioned probe. Inclusion of one reaction with 5 μl SD087 Binning DNA in initial MLPA experiments is essential as it can be used to aid in data binning of the peak pattern using Coffalyser.Net software. Furthermore, Binning DNA should be included in the experiment whenever changes have been applied to the set-up of the capillary electrophoresis device (e.g. when capillaries have been renewed). Binning DNA should never be used as a reference sample in the MLPA data analysis, neither should it be used in quantification of mutation signals, as for this purpose true mutation positive patient samples or cell lines should be used. It is strongly advised that all samples tested are extracted with the same method and derived from the same source of tissue. For further details, please consult the SD087 Binning DNA product description, available online:
www.mlpa.com.
Sample DNA
Sample DNA developed for this product: