Linked Life Data

15652243

Source:http://linkedlifedata.com/resource/pubmed/id/15652243

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2005-1-17
pubmed:abstractText
Human thiopurine S-methyltransferase (TPMT) catalyses the S-methylation of thiopurine drugs. TPMT is genetically polymorphic and is associated with large interindividual variations in thiopurine drug toxicity and therapeutic efficacy. During routine genotyping of patients with Crohn's disease, one novel missense mutation, 365A>C (TPMT*19, Lys(122)Thr), and a recently described missense mutation, 488G>A (TPMT*16, Arg(163)His), were identified in a Caucasian and a Moroccan patient, respectively. Using a heterologous yeast expression system, kinetic parameters (K(m) and V(max)) of the two variants with respect to 6-thioguanine S-methylation were determined and compared with those obtained with the wild-type enzyme. The Lys(122)Thr exchange did not significantly decrease the intrinsic clearance value (V(max)/K(m)) of the variant enzyme. In contrast, the Arg(163)His substitution significantly decreased the intrinsic clearance value by three-fold. The Arg(163) is located in a highly conserved region of the human TPMT protein and, as such, the Arg(163)His substitution is expected to result in a marked reduction of enzyme activity, as confirmed by the in vitro data. Phenotyping by measurement of red blood cell TPMT activity indicated that the patient heterozygous for the Lys(122)Thr mutation had normal TPMT activity, whereas the patient heterozygous for the Arg(163)His mutation was an intermediate methylator, which demonstrated a positive correlation between TPMT phenotyping and the in vitro data. The identification of a novel non-functional allele of the TPMT gene improves our knowledge of the genetic basis of interindividual variability in TPMT activity. These data further enhance the efficiency of genotyping methods to predict patients at risk of an inadequate response to thiopurine therapy.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0006-2952
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
69
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
525-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Identification and functional analysis of two rare allelic variants of the thiopurine S-methyltransferase gene, TPMT*16 and TPMT*19.
pubmed:affiliation
Equipe d'accueil EA2679, Faculté de Médecine, Pôle Recherche, Lille, France.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't