THROMBOSIS IN OTHERWISE WELL CHILDREN WITH THE FACTOR-V LEIDEN MUTATION

Objective: To determine whether resistance to activated protein C caus ed by the factor V Leiden mutation (Arg(506) to Gin) is associated wit h thrombosis occurring during childhood. Study design: Children with t hrombosis were screened for activated protein C resistance, Children f ound resistant to activated protein C had DNA analysis for the factor V Leiden mutation. family members of the children with activated prote in C resistance were similarly studied. Results: Three of fourteen chi ldren examined had abnormal normalized activated protein C sensitivity ratios. One child had protein S deficiency. The children had hyperlip idemia. Molecular confirmation of the factor V Leiden mutation was obt ained for all three children. Family members of each of the three chil dren were affected. Conclusions. Children have thromboses in associati on with the factor V Leiden mutation, as do adults. This mutation may be identified as an isolated risk factor or in association with other risk factors for thrombosis.