Homozygous antithrombin deficiency type II (99 Leu to Phe mutation) and childhood thromboembolism

We report 5 children from 3 families with homozygous antithrombin deficienc y type II affecting the heparin binding site (99 Leu to Phe mutation). Four children had severe spontaneous thromboembolic events (deep leg or caval v ein thrombosis, ischaemic stroke) at one week, 3 months, 13 and 14 years of ace. The fifth patient, a 17 year-old boy was asymptomatic. Early manifest ation of homozygous deficiency calls for prompt and accurate diagnosis. In doubtful cases genetic analysis is required, Long-term oral anticoagulation should be considered in affected individuals.