William E. Tidyman, Ph.D., M.S. is an Associate Specialist in the Department of Orofacial Science at the University of California at San Francisco with extensive research experience in the study of both cardiac and skeletal muscle gene regulation and development. He was a member of the team that identified the genes responsible for CFC. His current research includes how Ras/MAPK signaling regulates skeletal myogenesis and how germline dysregulation of this pathway affects muscle development and causes pathology.
Skeletal muscle pathology in Costello and cardio-facio-cutaneous syndromes: Developmental consequences of germline Ras/MAPK activation on myogenesis†
Version of Record online: 14 APR 2011
Copyright © 2011 Wiley-Liss, Inc.
American Journal of Medical Genetics Part C: Seminars in Medical Genetics
Special Issue: Disorders of the Ras Pathway
Volume 157, Issue 2, pages 104–114, 15 May 2011
How to Cite
Tidyman, W. E., Lee, H. S. and Rauen, K. A. (2011), Skeletal muscle pathology in Costello and cardio-facio-cutaneous syndromes: Developmental consequences of germline Ras/MAPK activation on myogenesis. Am. J. Med. Genet., 157: 104–114. doi: 10.1002/ajmg.c.30298
How to Cite this Article: Tidyman WE, Lee HS, Rauen KA. 2011. Skeletal muscle pathology in Costello and cardio-facio-cutaneous syndromes: Developmental consequences of germline Ras/MAPK activation on myogenesis. Am J Med Genet Part C Semin Med Genet 157:104–114.
- Issue online: 19 APR 2011
- Version of Record online: 14 APR 2011
- cardio-facio-cutaneous syndrome;
- Costello syndrome;
- signal transduction pathway;
- skeletal myogenesis;
- type 2 predominance
Cardio-facio-cutaneous syndrome (CFC) and Costello syndrome (CS) are two of the more rare RASopathies caused by altered signal transduction of the Ras/mitogen-activated protein kinase (MAPK) pathway. All of the RASopathies exhibit some degree of hypotonia, but CS and CFC are more severe. To determine if individuals with CS and CFC have an underlying skeletal myopathy, we systematically evaluated skeletal muscle pathology in both conditions. We reviewed pathology reports from six individuals who had undergone a skeletal muscle biopsy, and we reviewed histology slides on two cases with CS and one case with CFC. All patients in the cohort had histopathologic findings, and two consistent abnormalities were identified. The first was the presence of abnormal muscle fiber size and variability, and the second was the presence of type 2 fiber predominance. Given the degree of hypotonia typically present in these patients, the overall architecture of the muscle was relatively normal, without showing indications of severe structural histopathology or metabolic abnormalities. Because the Ras/MAPK pathway is vital for skeletal myogenesis, we evaluated the effects of CS and CFC mutations on myogenesis using C2C12 myoblasts. All CS/CFC mutations inhibited myoblast differentiation as indicated by fewer myosin heavy chain expressing cells and a decrease in the number of myotubes as compared to controls. These findings indicate that CS and CFC may have a true myopathy related to an inherent dysregulation of skeletal myogenesis, which further expands our understanding of the consequences of germline Ras/MAPK mutations. © 2011 Wiley-Liss, Inc.