Acetylcholine receptor α-subunit isoforms are differentially expressed in thymuses from myasthenic patients

Francesca Andreetta, Fulvio Baggi, Carlo Antozzi, Elena Torchiana, Pia Bernasconi, Ornella Simoncini, Ferdinando Cornelio, Renato Mantegazza

Research output: Contribution to journalArticlepeer-review


A central role of the thymus in autosensitization to the acetylcholine receptor has been proposed to explain the immunopathogenetic processes in myasthenia gravis (MG). Two isoforms of the α-subunit of the acetylcholine receptor are known; they differ by a 25-amino-acid insertion coded by the P3A exon. We investigated the expression of the P3A exon by RNA polymerase chain reaction in fetal and adult human myoblasts and TE671 cells; both isoforms were expressed. Muscle biopsies from patients with MG, Duchenne muscular dystrophy, and polymyositis were also studied and it was again found that both isoforms were expressed, indicating that the P3A exon is not associated with autoimmune, degenerative, and inflammatory muscle diseases. When P3A expression was studied in thymus samples from normal subjects and from thymectomized MG patients, the P3A+ subunit was absent in 75% of patients with involuted thymus and in all patients with thymomas but was present in normal thymuses and in patients with hyperplasia. Differential expression of the α-subunit isoforms of the acetylcholine receptor within the thymus may play a role in the immune pathogenesis of MG.

Original languageEnglish
Pages (from-to)341-348
Number of pages8
JournalAmerican Journal of Pathology
Issue number1
Publication statusPublished - 1997

ASJC Scopus subject areas

  • Pathology and Forensic Medicine


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