The UK MRC Mitochondrial Disease Patient Cohort Study: clinical phenotypes associated with the m.3243A>G mutation—implications for diagnosis and management. Issue 8 (25th January 2013)

• Record Type: Journal Article
• Authors: Nesbitt, Victoria; Pitceathly, Robert D S; Turnbull, Doug M; Taylor, Robert W; Sweeney, Mary G; Mudanohwo, Ese E; Rahman, Shamima; Hanna, Michael G; McFarland, Robert
• Is Part Of: Journal of neurology, neurosurgery and psychiatry. Volume 84:Issue 8(2013)
• Page Start: 936
• Page End: 938
• Publication Date: 2013-01-25
• Subjects: Mitochondrial Disorders -- Epidemiology -- Diabetes Mellitus -- Epilepsy -- Clinical Neurology; Neurology -- Periodicals; Nervous system -- Surgery -- Periodicals; Psychiatry -- Periodicals; 616.8
• DOI: 10.1136/jnnp-2012-303528
• Languages: English
• ISSNs: 0022-3050

Abstract

Abstract : Background: Population-based studies suggest the m.3243A>G mutation in MTTL1 is the most common disease-causing mtDNA mutation, with a carrier rate of 1 in 400 people. The m.3243A>G mutation is associated with several clinical syndromes including mitochondrial encephalopathy lactic acidosis and stroke-like episodes (MELAS), maternally inherited deafness and diabetes (MIDD) and progressive external ophthalmoplegia (PEO). Many patients affected by this mutation exhibit a clinical phenotype that does not fall within accepted criteria for the currently recognised classical mitochondrial syndromes. Methods: We have defined the phenotypic spectrum associated with the m.3243A>G mtDNA mutation in 129 patients, from 83 unrelated families, recruited to the Mitochondrial Disease Patient Cohort Study UK. Results: 10% of patients exhibited a classical MELAS phenotype, 30% had MIDD, 6% MELAS/MIDD, 2% MELAS/chronic PEO (CPEO) and 5% MIDD/CPEO overlap syndromes. 6% had PEO and other features of mitochondrial disease not consistent with another recognised syndrome. Isolated sensorineural hearing loss occurred in 3%. 28% of patients demonstrated a panoply of clinical features, which were not consistent with any of the classical syndromes associated with the m.3243A>G mutation. 9% of individuals harbouring the mutation were clinically asymptomatic. Conclusion: Following this study we propose guidelines for screening and for the management of confirmed cases.