Beggs, A., Haselkorn, T., Dhawan, A., Lawlor, M., Kim, J., Ward, E., Hughes, Z., Baima, J., James, L., Coats, J., Gentyala, R., Brandon, T., Garcia-Malo, M. Jesus Perez Inigo, Marini Bettolo, C., Graham, R., and Dowling, J.
X-linked myotubular myopathy (XL-MTM) is a rare life-threatening congenital myopathy caused by mutations in the MTM1 gene that encodes myotubularin, a ubiquitous enzyme required for normal development and function of skeletal muscle. The incidence of XLMTM in newborn males is 1:50,000. Recent evidence has revealed a previously unrecognized cholestatic tendency in patients with XL-MTM. EXCEL is a 48-week, prospective, observational, multicenter study to evaluate hepatobiliary health in patients with XLMTM. Approximately 50 male participants <18 years of age (up to half <5 years of age) with genetically confirmed XLMTM will be enrolled at 15–25 specialist sites in Canada, UK, and USA. The primary objective is to assess hepatobiliary health by estimating the incidence and prevalence of cholestatic complications in participants with XL-MTM. Secondary objectives are to evaluate the: (1) association between genetic variants of MTM1 and cholestasis; (2) association between environmental modifiers and cholestasis; and (3) healthcare utilization related to hepatobiliary and cholestatic complications. Participant assessments will be performed at the investigator's discretion based on standard of care at the site. A recommended schedule of assessments includes liver function tests (including serum bile acids), blood clotting parameters, creatinine, triglycerides and total cholesterol, and vitamin panel. Further clinical evaluation including liver ultrasound and Fibroscan will be used where appropriate. To reduce patient and caregiver burden, home healthcare services will collect laboratory tests when possible. Remote data collection may be used for healthcare resource utilization and patient medical history. Findings are expected to improve our understanding of cholestatic tendencies in participants with XL-MTM and provide critical information to improve the current management and treatment of XL-MTM, as well as future clinical trial designs. *Co-first authors. [ABSTRACT FROM AUTHOR]