New mutations in TK2 gene associated with mitochondrial DNA depletion.

Abstract

Mitochondrial deoxyribonucleic acid depletion syndromes are autosomal recessive disorders characterized by a reduction of the amount of mitochondrial deoxyribonucleic acid, which impairs the synthesis of respiratory chain complexes. Mutations in the deoxyguanosine kinase and polymerase gamma genes have been identified in hepatocerebral forms, whereas thymidine kinase 2 gene mutations have been found in patients with isolated myopathy, encephalomyopathy, or spinal muscular atrophy. Mutations in the gene encoding the beta subunit of the adenosine diphosphate-forming succinyl-coenzyme A synthetase have also been reported in a family. In this report, the clinical, molecular, morphologic, and biochemical features of five children from two independent families with an infantile encephalomyopathy are characterized. The affected children manifested muscle mitochondrial deoxyribonucleic acid depletion and three novel thymidine kinase 2 gene mutations. They consist of a homozygous substitution resulting in Ala to Val change at the highly conserved position 181 of thymidine kinase in the first family, and two heterozygous substitutions in the second family: a Cys to Trp change at residue 108 and a Leu to Pro change at residue 257 of the enzyme. Common clinical features associated with these TK2 mutations are a normal early developmental phase followed by psychomotor regression, encephalopathy often with epileptic seizures, and myopathy with features of a progressive dystrophic process.

• Authors: Sara Galbiati, Andreina Bordoni, Dimitra Papadimitriou, Antonio Toscano, Carmelo Rodolico, Efi Katsarou, Monica Sciacco, Anastasia Garufi, Alessandro Prelle, M 'hammed Aguennouz, Maria Bonsignore, Marco Crimi, Andrea Martinuzzi, Nereo Bresolin, Alex Papadimitriou, Giacomo P Comi
• Journal: Pediatric neurology (Pediatr Neurol) Vol. 34 Issue 3 Pg. 177-85 (Mar 2006) ISSN: 0887-8994 [Print] United States
• PMID: 16504786 (Publication Type: Case Reports, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• DNA, Mitochondrial
• Electron Transport Complex IV
• thymidine kinase 2
• Thymidine Kinase

Topics

• Amino Acid Substitution (genetics)
• Biopsy
• Child
• Child, Preschool
• Chromosome Aberrations
• DNA Mutational Analysis
• DNA, Mitochondrial (genetics)
• Diagnosis, Differential
• Disease Progression
• Electron Transport Complex IV (genetics)
• Epilepsy (diagnosis, genetics)
• Female
• Genes, Recessive (genetics)
• Genetic Carrier Screening
• Genotype
• Homozygote
• Humans
• Infant
• Male
• Mitochondrial Encephalomyopathies (diagnosis, genetics)
• Muscle, Skeletal (pathology)
• Phenotype
• Psychomotor Disorders (diagnosis, genetics)
• Thymidine Kinase (genetics)