Résumé :
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Autosomal dominant Emery-Dreifuss dystrophy (EDMD) is caused by LMNA gene mutation while mutations in the collagen VI genes (COL6A1, COL6A2, and COL6A3) cause Bethlem myopathy (BM) and Ullrich congenital muscular dystrophy (UCMD). The presence of contractures, with a muscular dystrophy pattern is found in both conditions, making the differential diagnosis sometimes complex. In this context, the recognition of a specific muscle pattern involvement using straightforward imaging techniques may orient clinicians to appropriate genetic analysis. In a retrospective study we assessed upper and lower limb muscle CT scanner in two patient cohorts suffering from either LMNA mutated EDMD or COL6 mutated BM or UCMD. We systematically assessed fatty infiltration level and distribution, muscle volume, and fascia appearance of selected muscles in all patients. Assessment was performed by two independent blinded investigators. In both groups, important fatty infiltration was found in the thighs. However, rectus femoris infiltration was selectively present in BM/UCMD patients; posterior thigh muscles fatty infiltration was significantly found in EDMD patients. In upper arms, severe infiltration was found in triceps and biceps muscles in BM/UCMD patients. A detailed analysis will be presented. From this study, we can conclude that EDMD and BM/UCMD contractile myopathies are characterized by a selective pattern of muscle involvement especially in thigh muscles. Assessing fatty infiltration level with a standard CT scanner technique in selected muscles may help differentiating both conditions and orientating towards appropriate genetic analysis.
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