Studying familial forms of systemic scleroderma offers several advantages:

1. To better understand the pathophysiology of a complex autoimmune disease based on "extreme" cases (familial forms);
2. To identify potential molecular markers predictive of disease progression;
3. To identify potential pathophysiological targets for developing new therapies, particularly relevant in severe and refractory forms of the disease.

Inclusion Criteria:

• Adult subjects (≥ 18 years of age)
• Subjects diagnosed with systemic scleroderma by a clinician (including limited, diffuse, and sine scleroderma SSc, as well as overlap syndromes with myositis) and meeting at least the VEDOSS criteria: Raynaud's phenomenon + 1 other criterion from among: sausage fingers, antinuclear antibodies, scleroderma-specific antibodies (anti-centromere, anti-RNApolIII, anti-ScL70), capillaroscopic abnormalities
• At least one first-degree relative with systemic scleroderma meeting the same criteria

Exclusion Criteria:

- Subject who has expressed opposition to participating in the study

Adult subjects diagnosed with systemic scleroderma by a clinician