Preferential central nucleation of type 2 myofibers is an invariable feature of myotonic dystrophy type 2.
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.
Pisani
Valerio
V
Department of Neurosciences, Università di Roma "Tor Vergata," and IRCCS Fondazione Santa Lucia, Via Montpellier 1, I 00133, Rome, Italy.
Panico
Maria Beatrice
MB
Department of Neurosciences, Università di Roma "Tor Vergata," and IRCCS Fondazione Santa Lucia, Via Montpellier 1, I 00133, Rome, Italy.
Terracciano
Chiara
C
Department of Neurosciences, Università di Roma "Tor Vergata," and IRCCS Fondazione Santa Lucia, Via Montpellier 1, I 00133, Rome, Italy.
Bonifazi
Emanuela
E
Department of Biopathology, Università di Roma "Tor Vergata," Rome, Italy.
Meola
Giovanni
G
Department of Neurology, Università di Milano, IRCCS Policlinico San Donato, Milano, Italy.
Novelli
Giuseppe
G
Department of Biopathology, Università di Roma "Tor Vergata," Rome, Italy.
Bernardi
Giorgio
G
Department of Neurosciences, Università di Roma "Tor Vergata," and IRCCS Fondazione Santa Lucia, Via Montpellier 1, I 00133, Rome, Italy.
Angelini
Corrado
C
Department of Neurological Sciences, Università di Padova, Padova, Italy.
Massa
Roberto
R
Department of Neurosciences, Università di Roma "Tor Vergata," and IRCCS Fondazione Santa Lucia, Via Montpellier 1, I 00133, Rome, Italy.
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
D000251:Adenosine Triphosphatases; D018995:Myosin Heavy Chains