A modification of the APC resistance test and its application to the study of patients on coumarin therapy.
APC resistance appears to be caused, predominantly, by a mutation in coagulation factor V (nucleotide 1691: G to A). This phenomenon is usually studied by performing APTTs in the absence and presence of added APC. We studied a modification of the assay involving dilution of the test plasma in factor V deficient plasma, to render the assay more factor V specific. This modification was applied to 76 patients with venous thrombosis on coumarin treatment and to 45 controls. Two out of 45 controls (4.4%) showed abnormal results with the modified test. They also showed loss of factor V exon 10 Mnl I restriction site, associated to APC resistance. All remaining controls, with normal functional results by the modified assay, showed normal restriction profile. We detected 9 affected patients (11.8%), one of them homozygous or double heterozygous. In conclusion, the modified assay is very sensitive for factor V dependent APC resistance, and can successfully be applied to patients on coumarin therapy.
Jorquera
J I
JI
Research and Development Division, Grifols Institute, Barcelona, Spain.
Aznar
J
J
Fernández
M A
MA
Montoro
J M
JM
Curats
R
R
Casaña
P
P
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use*; D016022:Case-Control Studies; D003374:Coumarins / Q000627:therapeutic use*; D004351:Drug Resistance / Q000235:genetics; D005166:Factor V Deficiency / Q000097:blood* / Q000235:genetics; D006801:Humans; D008875:Middle Aged; D009154:Mutation; D011486:Protein C / Q000819:agonists; D013924:Thrombophlebitis / Q000097:blood / Q000188:drug therapy*
D000925:Anticoagulants; D003374:Coumarins; D011486:Protein C; C030123:coumarin