Resistencia a la proteína C activada: estudio de laboratorio y prevalencia del defecto en la población chilena / Activated protein C resistance: laboratory study and prevalence of the defect in chilean population

Activated protein C resistance (APCR) or factor V leiden has been recently described as the most prevalent hemostatic abnormality associated with venous thrombosis. In patients with familial thrombophilia, the prevalence of APCR is 19-60 percent and around 20 percent in sporadic venous thrombosis. APCR is usually measured by the degree of prolongation of activated Partial Thromboplastin Time (APTT) on patient's plasma, induced by addition of APC in comparison to normal plasma. At the molecular level the defect is caused by a single-point mutation in the gene for factor V (FV) (G1.691-A), that predict the replacement of Arg506 by Glutamine. This mutation makes activated factor V resistant to inactivation by APC. Since the prevalence of the defect is highly variable among different populations, the objective of this work was to study its frequency in our population and in patients with thrombophilia. We defined the normal range for APTT ratio (APTT+APC/APTT-APC) in a group of 73 healthy volunteers in whom the presence of FV Q506 mutation was searched using Mnll enzyme digestion of PCR amplified genomic fragment containing the nucleotide 1.691. The lower limit of APTT ratio stablished in this group was 2.13. APCR was found in 6 out of 159 control subjects (3.8 percent) and in 14/50 (28 percent) of patients with thrombosis. In 13 cases as a single defect and in 1 associated to type I protein C deficiency. All the APCR patients and control subjects were heterozygotes by gene analysis. The results demonstrate that in our population APCR is also the most common defect associated with thrombosis, in accordance with a high prevalence in the population. The ability to screen for this defect will permit the identification of carriers that would benefit preventive therapy at risk situations

Deficiencia del factor V (parahemofilia) en una familia mexicana: primer informe de México / Coagulation factor V deficiency in a Mexican family

Se describe la primer familia mexicana, mestiza, con deficiencia congénita del factor V de la coagulación (Parahemofilia). Cinco miembros de dos generaciones de esta familia tuvieron la deficiencia, con valores procoagulantes del factor V entre 25 y 56% (Normal 80 a 120%). Además, un miembro de la familia, sin la deficiencia, nació con labio leporino y paladar hendido. La familia descrita es originaria de una zona del Estado de Puebla, donde se han identificado otras deficiencias heredadas de factores de la coagulación y aparentemente no hay antecedentes de consanguinidad

Deficiencia congénita combinada de los factores V y VII de la coagulación en una familia mexicana: deficiencia Toledo-Tehuantepec, un nuevo trastomo / Coagulation factors V and VII combined congenital deficiency in a Mexican family: Toledo-Tehuantepec deficiency, a new pathological entity

Se encontró deficiencia combinada de los factores V y VII de la coagulación de los miembros de una femilia originaria de Espinal, Oxaca, en el Istmo de Tehuantepec. Los padres son consanguíneos, y ambos tienen el apellido Toledo. Hay labio leporino en el padre y un hijo. Ningún familiar tiene hemorragias anormales pero sus estudios de coagulación del tiempo de protrombina y de tromboplastina parcial resultaron prologados. El padre es deficiente en factor V, la madre en factor VII, y sus hijos heredaron ambas deficiencias (V y VII), lo que indica una transmisión autosómica dominante y el patrón del estado heterocigoto. Esta deficiencia no se ha descrito previamente, por lo que cabe reconocerla con el nombre Toledo-Tehuantepec