title: Primary beta-sarcoglycanopathy manifesting as recurrent exercise-induced myoglobinuria.
abstract: 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.
authors.affiliation: Centro Dino Ferrari, Istituto di Clinica Neurologica, Università degli Studi di Milano, IRCCS Ospedale Maggiore Policlinico, Via F. Sforza 35, 20122, Milan, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Cagliani
authors.forename: G P
authors.initials: GP
authors.lastname: Comi
authors.forename: L
authors.initials: L
authors.lastname: Tancredi
authors.forename: M
authors.initials: M
authors.lastname: Sironi
authors.forename: F
authors.initials: F
authors.lastname: Fortunato
authors.forename: R
authors.initials: R
authors.lastname: Giorda
authors.forename: A
authors.initials: A
authors.lastname: Bardoni
authors.forename: M
authors.initials: M
authors.lastname: Moggio
authors.forename: A
authors.initials: A
authors.lastname: Prelle
authors.forename: N
authors.initials: N
authors.lastname: Bresolin
authors.forename: G
authors.initials: G
authors.lastname: Scarlato
mesh_terms: 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
chemical_list: D003598:Cytoskeletal Proteins; C483081:DAG1 protein, human; D008562:Membrane Glycoproteins; D049030:Dystroglycans