Phenotypic spectrum associated with mutations of the mitochondrial polymerase gamma gene.

TitlePhenotypic spectrum associated with mutations of the mitochondrial polymerase gamma gene.
Publication TypeJournal Article
Year of Publication2006
AuthorsHorvath, R, Hudson, G, Ferrari, G, Fütterer, N, Ahola, S, Lamantea, E, Prokisch, H, Lochmüller, H, McFarland, R, Ramesh, V, Klopstock, T, Freisinger, P, Salvi, F, Mayr, JA, Santer, R, Tesarova, M, Zeman, J, Udd, B, Taylor, RW, Turnbull, D, Hanna, M, Fialho, D, Suomalainen, A, Zeviani, M, Chinnery, PF
JournalBrain
Volume129
IssuePt 7
Pagination1674-84
Date Published2006 Jul
ISSN1460-2156
KeywordsAdolescent, Adult, Age of Onset, Child, Child, Preschool, Diffuse Cerebral Sclerosis of Schilder, DNA Polymerase gamma, DNA, Mitochondrial, DNA-Directed DNA Polymerase, Female, Gene Frequency, Heredodegenerative Disorders, Nervous System, Humans, Infant, Male, Middle Aged, Mitochondrial Diseases, Mitochondrial Encephalomyopathies, Mutation, Ophthalmoplegia, Chronic Progressive External, Phenotype, Sex Factors
Abstract

Mutations in the gene coding for the catalytic subunit of the mitochondrial DNA (mtDNA) polymerase gamma (POLG1) have recently been described in patients with diverse clinical presentations, revealing a complex relationship between genotype and phenotype in patients and their families. POLG1 was sequenced in patients from different European diagnostic and research centres to define the phenotypic spectrum and advance understanding of the recurrence risks. Mutations were identified in 38 cases, with the majority being sporadic compound heterozygotes. Eighty-nine DNA sequence changes were identified, including 2 predicted to alter a splice site, 1 predicted to cause a premature stop codon and 13 predicted to cause novel amino acid substitutions. The majority of children had a mutation in the linker region, often 1399G-->A (A467T), and a mutation affecting the polymerase domain. Others had mutations throughout the gene, and 11 had 3 or more substitutions. The clinical presentation ranged from the neonatal period to late adult life, with an overlapping phenotypic spectrum from severe encephalopathy and liver failure to late-onset external ophthalmoplegia, ataxia, myopathy and isolated muscle pain or epilepsy. There was a strong gender bias in children, with evidence of an environmental interaction with sodium valproate. POLG1 mutations cause an overlapping clinical spectrum of disease with both dominant and recessive modes of inheritance. 1399G-->A (A467T) is common in children, but complete POLG1 sequencing is required to identify multiple mutations that can have complex implications for genetic counselling.

DOI10.1093/brain/awl088
Alternate JournalBrain
Citation Key10.1093/brain/awl088
PubMed ID16621917
Grant ListG108/539 / / Medical Research Council / United Kingdom
GGP030039 / / Telethon / Italy
/ / Wellcome Trust / United Kingdom