Characteristic findings of skeletal muscle MRI in caveolinopathies

Area of Science:

• Neurology
• Genetics
• Medical Imaging

Background:

• Caveolinopathies encompass diverse phenotypes including rippling muscle disease (RMD), limb-girdle muscular dystrophy, and hypertrophic cardiomyopathy, all linked to CAV3 gene mutations.
• These conditions can also arise from secondary caveolin-3 deficiency, as seen in polymerase I and transcript release factor (PTRF) mutations.

Observation:

• This study analyzed skeletal muscle MRI findings in four patients with childhood-onset RMD due to CAV3 mutations and one patient with congenital generalized lipodystrophy type 4 (PTRF mutation).
• Muscle MRI highlighted the rectus femoris and semitendinosus muscles as most frequently affected in RMD patients.
• Peripheral rectus femoris changes were specific and detectable even in young patients, with disease progression showing involvement in semitendinosus, biceps femoris, and gracilis muscles.

Findings:

• A consistent pattern of skeletal muscle involvement was observed across different caveolinopathy phenotypes.
• Interestingly, patients with secondary caveolin deficiency due to PTRF mutations exhibited the same characteristic MRI patterns as those with primary CAV3 mutations.

Implications:

• Skeletal muscle imaging provides specific diagnostic findings for caveolinopathies, irrespective of the underlying genetic cause (primary CAV3 mutation or secondary PTRF mutation).
• These imaging biomarkers can aid in the diagnosis and understanding of the spectrum of caveolinopathies.