title: Factor V antigen levels in APC resistance, in factor V deficiency and in combined APC resistance and factor V deficiency (pseudohomozygosis for APC resistance).
abstract: Factor V antigen levels were measured in 40 patients with factor V deficiency (11 homozygous and 29 heterozygous), in 38 patients with factor V Leiden mutation (16 homozygous and 22 heterozygous) and in three patients with combined heterozygous factor V deficiency and heterozygous factor V Leiden mutation (so-called pseudohomozygosis for APC resistance). Twenty normal subjects of both sexes served as controls. Factor V antigen levels compared well with factor V activity in normal subjects and in all groups of patients. They were normal both in homozygous and heterozygous APC resistance patients. Factor V antigen determination may be useful for the diagnosis of pseudohomozygosis for APC resistance. These patients have a phenotypic picture similar to homozygous APC resistance, but show a factor V antigen level about half the normal value since they are compound heterozygotes for factor V deficiency and APC resistance. In contrast, homozygous patients for APC resistance show normal factor V activity and antigen levels.
authors.affiliation: University of Padua Medical School, Institute of Medical Semeiotics, Padua, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Girolami
authors.forename: P
authors.initials: P
authors.lastname: Simioni
authors.forename: U
authors.initials: U
authors.lastname: Venturelli
authors.forename: B
authors.initials: B
authors.lastname: Girolami
authors.forename: E
authors.initials: E
authors.lastname: Zanon
mesh_terms: D004351:Drug Resistance; D004797:Enzyme-Linked Immunosorbent Assay; D005165:Factor V / Q000235:genetics / Q000378:metabolism*; D005166:Factor V Deficiency / Q000235:genetics / Q000378:metabolism*; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D010641:Phenotype; D011486:Protein C / Q000494:pharmacology*
chemical_list: D011486:Protein C; C095381:factor V Leiden; D005165:Factor V