• Johanna Uusimaa, Jukka S Moilanen, Leena Vainionpää, Päivi Tapanainen, Päivi Lindholm, Matti Nuutinen, Tuija Löppönen, Elina Mäki-Torkko, Heikki Rantala, and Kari Majamaa.
• Department of Paediatrics, University of Oulu, Oulu, Finland.
• Ann. Neurol. 2007 Sep 1;62(3):278-87.

ObjectiveWe studied the prevalence, segregation, and phenotype of the mitochondrial DNA 3243A>G mutation in children in a defined population in Northern Ostrobothnia, Finland.MethodsChildren with diagnoses commonly associated with mitochondrial diseases were ascertained. Blood DNA from 522 selected children was analyzed for 3243A>G. Children with the mutation were clinically examined. Information on health history before the age of 18 years was collected from previously identified adult patients with 3243A>G. Mutation segregation analysis in buccal epithelial cells was performed in mothers with 3243A>G and their children whose samples were analyzed anonymously.ResultsEighteen children were found to harbor 3243A>G in a population of 97,609. A minimum estimate for the prevalence of 3243A>G was 18.4 in 100,000 (95% confidence interval, 10.9-29.1/100,000). Information on health in childhood was obtained from 37 adult patients with 3243A>G. The first clinical manifestations appearing in childhood were sensorineural hearing impairment, short stature or delayed maturation, migraine, learning difficulties, and exercise intolerance. Mutation analysis from 13 mothers with 3243A>G and their 41 children gave a segregation rate of 0.80. The mothers with heteroplasmy greater than 50% tended to have offspring with lower or equal heteroplasmy, whereas the opposite was true for mothers with heteroplasmy less than or equal to 50% (p = 0.0016).InterpretationThe prevalence of 3243A>G is relatively high in the pediatric population, but the morbidity in children is relatively low. The random genetic drift model may be inappropriate for the transmission of the 3243A>G mutation.

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