title: Preferential central nucleation of type 2 myofibers is an invariable feature of myotonic dystrophy type 2.
abstract: The clinical features of myotonic dystrophy type 1 (DM1) and type 2 (DM2) may present striking similarity, whereas, in some cases, the DM2 phenotype may be so mild that the diagnosis may be missed. Therefore, the identification of disease-specific histopathological patterns for DM1 and DM2 may help clinicians to correctly address genetic studies. We performed a comparative morphological and morphometric analysis on muscle biopsies from 10 DM1 and 11 DM2 patients, comparing type 1 and type 2 fibers as to: fiber type predominance, transverse diameter, atrophy and hypertrophy factors, and prevalence of central nuclei. In DM1 cases we observed preferential type 1 fiber atrophy and a higher prevalence of central nucleation among type 1 fibers in all cases. In DM2 muscle biopsies, high rates of atrophic and hypertrophic type 2 fibers were observed in most cases, and preferential central nucleation in type 2 fibers was present in all cases. As opposed to DM1, in which type 1 fibers display most of the histological changes, preferential atrophy and hypertrophy of type 2 fibers may be considered as markers of DM2. A higher prevalence of central nuclei among hypertrophic type 2 fibers has a predictive value for the diagnosis of DM2. Thus, morphometric and fiber type-based histological analysis of muscle biopsies may help differentiate between DM1 and DM2 and guide molecular analysis.
authors.affiliation: Department of Neurosciences, Università di Roma "Tor Vergata," and IRCCS Fondazione Santa Lucia, Via Montpellier 1, I 00133, Rome, Italy.
authors.forename: Valerio
authors.initials: V
authors.lastname: Pisani
authors.affiliation: Department of Neurosciences, Università di Roma "Tor Vergata," and IRCCS Fondazione Santa Lucia, Via Montpellier 1, I 00133, Rome, Italy.
authors.forename: Maria Beatrice
authors.initials: MB
authors.lastname: Panico
authors.affiliation: Department of Neurosciences, Università di Roma "Tor Vergata," and IRCCS Fondazione Santa Lucia, Via Montpellier 1, I 00133, Rome, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Terracciano
authors.affiliation: Department of Biopathology, Università di Roma "Tor Vergata," Rome, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Bonifazi
authors.affiliation: Department of Neurology, Università di Milano, IRCCS Policlinico San Donato, Milano, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Meola
authors.affiliation: Department of Biopathology, Università di Roma "Tor Vergata," Rome, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Novelli
authors.affiliation: Department of Neurosciences, Università di Roma "Tor Vergata," and IRCCS Fondazione Santa Lucia, Via Montpellier 1, I 00133, Rome, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Bernardi
authors.affiliation: Department of Neurological Sciences, Università di Padova, Padova, Italy.
authors.forename: Corrado
authors.initials: C
authors.lastname: Angelini
authors.affiliation: Department of Neurosciences, Università di Roma "Tor Vergata," and IRCCS Fondazione Santa Lucia, Via Montpellier 1, I 00133, Rome, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Massa
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000328:Adult; D000368:Aged; D001706:Biopsy / Q000379:methods; D002467:Cell Nucleus / Q000378:metabolism / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000473:pathology*; D018995:Myosin Heavy Chains / Q000378:metabolism; D009223:Myotonic Dystrophy / Q000145:classification* / Q000175:diagnosis* / Q000378:metabolism
chemical_list: D000251:Adenosine Triphosphatases; D018995:Myosin Heavy Chains