Hereditary thrombosis in a Utah kindred is caused by a dysfunctional antithrombin III gene

Maximum likelihood analysis of linkage between antithrombin III (ATIII) DNA polymorphisms and ATIII deficiency in a large Utah kindred suggests that thrombotic disease in this family is caused by a dysfunctional ATIII gene. ATIII-deficient family members were identified on the basis of: (1) reduced anticoagulant activity and (2) the presence of an electrophoretically abnormal inhibitor molecule in their plasmas. Affected individuals have two copies of the ATIII structural gene, and both alleles appear normal at the resolution of whole genome Southern blotting. However, family studies revealed statistically significant cosegregation of ATIII-deficiency trait and a particular ATIII DNA polymorphism haplotype (lod = 3.35; theta = 0.0); this result is consistent with the presence of a dysfunctional ATIII gene on a chromosome of the +, S haplotype.