Limb girdle muscular dystrophies (LGMD) are a very heterogeneous group of muscle disorders characterized by muscle weakness and atrophy of the proximal muscles of the shoulder and pelvic girdles. LGMD is classified based on its inheritance pattern and genetic cause into more than 31 different types. A new type - type 2T has been found. The genetic cause of type 2T is mutations in Guanosine Diphosphate (GDP)-mannose pyrophosphorylase B (GMPPB). Mutations in GMPPB can also cause Congenital muscular dystrophies (CMD). Only 41 patients with mutations in GMPPB has been reported. In this study, the investigators examine five new cases with the LGMD phenotype. The primary aim is to examine the muscle involvement using MRI.
Study Type
OBSERVATIONAL
Enrollment
4
Copenhagen Neuromuscular Center
Copenhagen, Copenhagen, Denmark
MRI scan for qualitative analysis of muscle involvement
The MRI protocol include T1-weighted brain and whole body examination. Four cross-sectional slices at shoulder, lumbar back, thigh and calf are chosen for qualitative analysis using the grading scale developed by Mercuri et al. (2007).
Time frame: One MRI scan per subject (exam lasts approximately 60 min.)
Muscle biopsy for biochemical investigation
Muscle biopsies from the tibialis anterior muscle and the deltoid muscle will be analyzed for glycosylated α-dystroglycan, merosin and GMPPB. (Concentration determined by standard biochemical analysis).
Time frame: One muscle biopsy per subject (last approximately 15 min.)
10 meter walk test
Measurement of the time it takes to walk 10 meters.
Time frame: Exam last approximately 5 min.
Neurological examination and test of muscle strength
Muscle strength (in arms and legs) will be examined based on the Medical Research Council (MRC) scale.
Time frame: Exam last approximately 15 min.
Questionnaires
Data will be collected using Minimal mental examination (MMSE) and Fatigue Severity Scale (FSS).
Time frame: Data will be collected once for patients with LGMD 2T (exam last approximately 45 min.)
Heart examination
Echocardiography and Electrocardiogram (ECG).
Time frame: Exam last approximately 45 min
Forced Vital Capacity (FVC)
FVC is measured as the best of three attempts using a hand-held spirometer.
Time frame: Exam last approximately 15 min
Electromyography (EMG)
EMG is used for measuring nerve conducting velocity and neuromuscular activity.
Time frame: Exam last approximately 30 min
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