Partial and severe factor XI deficiency in South Australia and the usefulness of factor XI mutation analysis for diagnosis.

Aims: To correlate the presence or absence of a factor XI gene mutation with factor XI activity in patients with severe or partial reduction in factor XI.

Methods: Patients previously found to have reduced factor XI levels were recalled for repeat testing and factor XI genetic analysis. Also, during the 18 month study period, any routine patient found to have an isolated reduced or low normal factor XI level had factor XI genetic analysis.