Heterocygous APC-resistance in a young infant with a thrombus in the pulmonary artery

A clinically healthy 6 week old infant underwent cardiological examination because of a slight heart murmur. On echocardiography, we detected a round thrombus of 4 millimeters diameter originating in the ductus arteriosus Bot alli and extending into the pulmonary artery. Molecular testing (PCR amplif ication method) revealed a heterozygous mutation responsible for factor V L eiden. No additional risk factors could be detected neither in the case his tory nor in the laboratory findings. The clinical course until the age of 1 7 months remained normal. She was not treated, but a prophylactical anticoa gulation is recommended for the case of risk situations (surgery, menstruat ion, pregnancy). Discussion: Until now carriers of the factor V Leiden were divided into sym ptomatic patients and healthy carriers. Our case shows, that heterozygous A PC-resistance may cause asymptomatic thrombosis in seemingly healthy neonat es.