[An infrequent cause of pulmonary thromboembolism].

We present a case of pulmonary thromboembolism in a young patient triggered by a long haul travel, in which a homocygotic mutation in the gene of the metilentetrahidrofolate reductase was demonstrated. This mutation can cause hyperhomocysteinemia that is a recognized risk factor for venous thromboembolism (VTE). In the management of these patients, the levels of homocysteine should be lowered, as well as use of thromboprophylaxis before transitory risk situations. It is important to know when the screening should be performed, because they are behind an important number of cases of VTE.