The main objective of this study is to evaluate, for 15 healthy volunteers and for 15 patients with a history of venous thromboembolism (VTE), the monthly variation (over 6 months) of plasma nucleosome and free DNA concentrations.

The secondary objectives of this study are:

A. To describe, for 15 healthy volunteers with no history of venous thromboembolism (VTE), plasma nucleosome and DNA concentrations.

B. To describe, for 100 patients with a history of VTE currently consulting for chronic disease or thrombophilia work-up, plasma nucleosome and DNA concentrations.

C. To compare plasma nucleosome and DNA concentrations between healthy volunteers and VTE patients

D. To describe, for 100 patients with a history of VTE currently consulting for chronic disease or thrombophilia work-up, the relationships between classification of VTE and plasma nucleosome concentrations:

• anatomical classification of VTE: (i)superficial, deep ((ii)distal or (iii)proximal), or (iv)pulmonary embolism
• circumstantial classification of VTE: (i) triggered, no chronic risk factor; (ii) untriggered, with chronic risk factor; (iii)triggered, with chronic risk factor; (iv) untriggered, no chronic risk factor (idiopathic)

E. To describe, for 100 patients with a history of VTE, the variation in plasma nucleosome concentrations 6 months after the first evaluation

• according to the above anatomical classification
• according to the above circumstantial classification
• according to intercurrent events and treatments

F. To compare the plasma concentrations of nucleosomes and free DNA

G. To evaluate the relationship between plasma nucleosome and free DNA concentrations and:

• circulating leukocyte populations: total leukocyte count, absolute number of neutrophils, monocytes, lymphocytes
• markers of coagulation activation: d-dimers, circulating fibrin monomers
• platelet count
• patients on antivitamin K: INR, patients receiving heparin: antiXa activity

H. Creation of a biological collection

Inclusion Criteria:

• The patient or volunteer must have given his/her informed and signed consent
• The patient or volunteer must be insured or beneficiary of a health insurance plan
• The patient or volunteer is available for 6 months of follow-up

For group "P":

• patient with a history of VTE

For group "T":

• healthy volunteer
• no history of VTE
• no history of chronic disease
• no history of neoplastic disease
• no history of chronic infection
• not taking anticoagulants, antiplatelet medications
• no acute disease or infection during the last 2 weeks

Exclusion Criteria:

• The patient is participating in another study
• The patient is in an exclusion period determined by a previous study
• The patient is under judicial protection, under tutorship or curatorship
• The patient refuses to sign the consent
• It is impossible to correctly inform the patient
• The patient is pregnant, parturient, or breastfeeding
• The patient gave birth in the past three months

The study population is composed of 15 healthy volunteers with no history of VTE (group "T") and 100 patients with VTE (group "P"). Fifteen randomly selected members of group P make up the sub-group "Px".