Primary beta-sarcoglycanopathy manifesting as recurrent exercise-induced myoglobinuria.
We report an unusual presentation of a primary beta-sarcoglycanopathy (LGMD type 2E). A 12- year-old boy came to our attention after six episodes of exercise-induced myoglobinuria. Electromyogram showed mild myopathic features of the proximal lower limb muscles. Electrocardiogram was normal. Neurological examination revealed normal muscle strength and reduced deep tendon reflexes. A muscle biopsy showed rare regenerating fibers; the immunohistochemistry was normal for dystrophin, while all the sarcoglycans were diffusely decreased. Western blot analysis showed a relevant decrease of all sarcoglycan proteins and a mild dystrophin reduction. beta-Sarcoglycan gene analysis demonstrated a compound heterozygous status for these mutations: a novel A-T base pair substitution at nucleotide 85 in exon 2, changing the codon Arg to a stop codon; a C-T base pair substitution at nucleotide 272 in exon 3 changing a Arg to a Cys residue. We consider that exercise-induced myoglobinuria may be the presenting sign of primary beta-sarcoglycanopathy.
Cagliani
R
R
Centro Dino Ferrari, Istituto di Clinica Neurologica, Università degli Studi di Milano, IRCCS Ospedale Maggiore Policlinico, Via F. Sforza 35, 20122, Milan, Italy.
Comi
G P
GP
Tancredi
L
L
Sironi
M
M
Fortunato
F
F
Giorda
R
R
Bardoni
A
A
Moggio
M
M
Prelle
A
A
Bresolin
N
N
Scarlato
G
G
D001483:Base Sequence / Q000235:genetics; D002648:Child; D003598:Cytoskeletal Proteins / Q000172:deficiency / Q000235:genetics*; D049030:Dystroglycans; D015444:Exercise / Q000502:physiology*; D006579:Heterozygote; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000235:genetics*; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D009136:Muscular Dystrophies / Q000235:genetics* / Q000378:metabolism / Q000652:urine*; D009154:Mutation / Q000235:genetics; D009212:Myoglobinuria / Q000209:etiology*; D012008:Recurrence
D003598:Cytoskeletal Proteins; C483081:DAG1 protein, human; D008562:Membrane Glycoproteins; D049030:Dystroglycans