Thromb Haemost 1996; 75(03): 417-421
DOI: 10.1055/s-0038-1650289
Original Article
Schattauer GmbH Stuttgart

Factor V Leiden (FV R506Q) in Families with Inherited Antithrombin Deficiency

H H van Boven
1   The Department of Clinical Epidemiology, University Hospital Leiden, The Netherlands
,
P H Reitsma
2   Hemostasis and Thrombosis Research Center, University Hospital Leiden, The Netherlands
,
F R Rosendaal
1   The Department of Clinical Epidemiology, University Hospital Leiden, The Netherlands
2   Hemostasis and Thrombosis Research Center, University Hospital Leiden, The Netherlands
,
T A Bayston
3   Department of Haematology, Charing Cross and Westminster Medical School, London
,
V Chowdhury
4   institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
,
Jeanne-Yvonne Borg
1   The Department of Clinical Epidemiology, University Hospital Leiden, The Netherlands
,
K A Bauer
5   Beth Israel Hospital, Boston; USA
1   The Department of Clinical Epidemiology, University Hospital Leiden, The Netherlands
,
I Scharrer
6   Johann Wolfgang Goethe Universitat, Frankfurt am Main, Germany
,
J Conard
7   Hôtel Dieu, Paris, France
,
D A Lane
3   Department of Haematology, Charing Cross and Westminster Medical School, London
› Author Affiliations
Further Information

Publication History

Received 06 September 1995

Accepted after resubmission 24 November 1995

Publication Date:
27 July 2018 (online)

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Summary

We investigated the presence of the gene mutation of factor V, FV R506Q or factor V Leiden, responsible for activated protein C resistance, in DNA samples of 127 probands and 188 relatives from 128 families with antithrombin deficiency. The factor V mutation was identified in 18 families. Nine families were available to assess the mode of inheritance and the clinical relevance of combined defects.

The factor V and antithrombin genes both map to chromosome 1. Segregation of the defects on opposite chromosomes was observed in three families. Co-segregation with both defects on the same chromosome was demonstrated in four families. In one family a de novo mutation of the antithrombin gene and in another a crossing-over event were the most likely explanations for the observed inheritance patterns.

In six families with type I or II antithrombin deficiency (reactive site or pleiotropic effect), 11 of the 12 individuals with both antithrombin deficiency and the factor V mutation developed thrombosis. The median age of their first thrombotic episode was 16 years (range 0-19); this is low compared with a median age of onset of 26 years (range 20-49) in 15 of 30 carriers with only a defect in the antithrombin gene. One of five subjects with only factor V mutation experienced thrombosis at 40 years of age. In three families with type II heparin binding site deficiencies, two of six subjects with combined defects experienced thrombosis; one was homozygous for the heparin binding defect.

Our results show that, when thrombosis occurs at a young age in antithrombin deficiency, the factor V mutation is a likely additional risk factor. Co-segregation of mutations in the antithrombin and factor V genes provides a molecular explanation for severe thrombosis in several generations. The findings support that combinations of genetic risk factors underly differences in thrombotic risk in families with thrombophilia.