The molecular basis of genetic predisposition to pulmonary tuberculosis in adults remains largely elusive. Few candidate genes have consistently been implicated in tuberculosis susceptibility, and no conclusive linkage was found in two previous genome-wide screens. We report here a genome-wide linkage study in a total sample of 96 Moroccan multiplex families, including 227 siblings with microbiologically and radiologically proven pulmonary tuberculosis. A genome-wide scan conducted in half the sample (48 families) identified five regions providing suggestive evidence (logarithm of the odds [LOD] score >1.17; P < 0.01) for linkage. These regions were then fine-mapped in the total sample of 96 families. A single region of chromosome 8q12-q13 was significantly linked to tuberculosis (LOD score = 3.49; P = 3 × 10−5), indicating the presence of a major tuberculosis susceptibility gene. Linkage was stronger (LOD score = 3.94; P = 10−5) in the subsample of 39 families in which one parent was also affected by tuberculosis, whereas it was much lower (LOD score = 0.79) in the 57 remaining families without affected parents, supporting a dominant mode of inheritance of the major susceptibility locus. These results provide direct molecular evidence that human pulmonary tuberculosis has a strong genetic basis, and indicate that the genetic component involves at least one major locus with a dominant susceptibility allele.

Objectives: To describe the clinical characteristics and muscle pathological features of patients with systemic sclerosis (SSc) and myopathy and analyse their impact on muscle outcome. Methods: Thirty-five patients with myopathy and available muscle biopsy were restrospectively investigated from the charts of four hospital centres. Results: Twenty-six (74%) cases had diffuse SSc. The median time from SSc diagnosis was 5 years (range 0–23) at myopathy onset. The main myopathological features were mononuclear inflammation (63%), muscle atrophy (60%), necrosis (59%), regeneration (44%), fibrosis (24%) or microangiopathy (27%). After a median follow-up of 4.4 years, 24 patients (69%) showed complete or partial muscle remission. Only histological muscle inflammation was associated with good muscle prognosis in multivariate analysis (odds ratio 44.7, 95% CI 2.8 to 704.7). Patients without muscle inflammation had a poor response to corticosteroids (38% favourable response vs 90% in patients with inflammation). Conclusion: Muscle histopathology is critical in the therapeutic management of SSc-associated myopathy.