ARMS TEST FOR DIAGNOSIS OF FACTOR V-LEIDEN MUTATION, A COMMON-CAUSE OF INHERITED THROMBOTIC TENDENCY

We developed a simple and rapid amplification-refractory mutation syst em (ARMS) assay for the factor V mutation [R506Q] (factor V-Leiden), w hich results in the autosomal dominant thrombotic tendency, resistance to activated protein C (rAPC). PCR primers within Exon 10 of the fact or V gene were designed. A common upstream primer was paired with eith er a mutant or wild-type-specific downstream primer. The 3'-most nucle otide of the specific primers recognized either the mutant or normal a llele, and the 3' penultimate nucleotide was mismatched to enhance spe cificity of the reaction. The assay was validated using authentic fact or V-Leiden DNA samples. Seven of 103 hematologically normal children (6.8%) were found to be heterozygotes. Among 27 patients studied by th e rAPC assay, ARMS assay and rAPC results were concordant in 26. Among these were a 1-year-old child with a calcified clot in the inferior v ena cava. Both the patient and his father were heterozygous for the mu tation and both had abnormal rAPC assays. rAPC and factor V-Leiden ass ays were discordant in a young girl with a history of stroke. Biochemi cal rAPC assay was abnormal, while ARMS assay revealed amplification o nly with wild-type primers, suggesting a non-[R506Q] mechanism for rAP C. This assay will be a valuable tool for studying subjects with throm boses and their family members. (C) 1996 Wiley-Liss, Inc.