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Lookup NU author(s): Dr Sarah PickettORCiD, Dr John Grady, Dr Yi NgORCiD, Professor Grainne Gorman, Dr Andrew Schaefer, Dr Ian Wilson, Professor Heather Cordell, Emeritus Professor Doug Turnbull, Professor Robert Taylor, Professor Bobby McFarlandORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Objective: The pathogenic mitochondrial DNA m.3243A>G mutation is associated with a wide range of clinical features, making disease prognosis extremely difficult to predict. We aimed to understand the cause of this heterogeneity.Methods: We examined the phenotypic profile of 238 adult m.3243A>G carriers (patients and asymptomatic carriers) from the UK MRC Mitochondrial Disease Patient Cohort using the Newcastle Mitochondrial Disease Adult Scale. We modeled the role of risk factors for the development of specific phenotypes using proportional odds logistic regression. As mitochondria are under the dual control of their own and the nuclear genome, we examined the role of additive nuclear genetic factors in the development of these phenotypes within 46 pedigrees from the cohort.Results: Seizures and stroke-like episodes affect 25% and 17% of patients, respectively; more common features include hearing impairment, gastrointestinal disturbance, psychiatric involvement, and ataxia. Age, age-adjusted blood heteroplasmy levels, and sex are poor predictors of phenotypic severity. Hearing impairment, diabetes, and encephalopathy show the strongest associations, but pseudo-R2 values are low (0.14-0.17). We found a high heritability estimate for psychiatric involvement (h2=0.76, P = 0.0003) and moderate estimates for cognition (h2=0.46, P = 0.0021), ataxia (h2 = 0.45, P = 0.0011), migraine (h2 = 0.41, P = 0.0138), and hearing impairment (h2 = 0.40, P = 0.0050).Interpretation: Our results provide good evidence for the presence of nuclear genetic factors influencing clinical outcomes in m.3234A>G-related disease, paving the way for future work identifying these through large-scale genetic linkage and association studies, increasing our understanding of the pathogenicity of m.3243A>G and providing improved estimates of prognosis.
Author(s): Pickett S, Grady JP, Ng YS, Gorman GS, Schaefer AM, Wilson IJ, Cordell HJ, Turnbull DM, Taylor RW, McFarland R
Publication type: Article
Publication status: Published
Journal: Annals of Clinical and Translational Neurology
Year: 2018
Volume: 5
Issue: 3
Pages: 333-345
Print publication date: 01/03/2018
Online publication date: 07/02/2018
Acceptance date: 21/12/2017
Date deposited: 18/04/2018
ISSN (electronic): 2328-9503
Publisher: John Wiley and Sons Ltd
URL: https://doi.org/10.1002/acn3.532
DOI: 10.1002/acn3.532
PubMed id: 29560378
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