THE ACTIVATED PROTEIN-C RESISTANCE PHENOTYPE OF THE ANTIPHOSPHOLIPID SYNDROME MAY FOLLOW A RELAPSING COURSE

Activated protein C resistance, the most frequent thrombophilic condit ion may be inherited or acquired: the antiphospholipid syndrome, eithe r primary or secondary is one of the causes of the acquired form. The case of a patient with a primary form of antiphospholipid syndrome in whom the activated protein C resistance phenotype was assessed in four instances during a 3-year period is presented. In two instances the a bnormal phenotype of the activated protein C resistance was present, w hereas in the other two it was absent. The factor V gene (G-->A, 1691) leading to the (R 506 Q) factor V mutation, typical of most inherited forms of the activated protein C resistance, was not found. The relap sing behavior of this phenomenon has not been previously shown. The ch anging pattern of this abnormality could explain discordant previous r eports about the prevalence of the activated protein C resistance phen otype in patients with primary or secondary forms of the antiphospholi pid syndrome.