Mitochondrial haplogroup H correlates with ATP levels and age at onset in Huntington disease.

Mitochondrial dysfunction has been implicated in the pathogenesis of Huntington disease (HD), a primarily neurodegenerative disorder that results from an expansion in the polymorphic trinucleotide CAG tract in the HD gene. In order to evaluate whether mitochondrial DNA (mtDNA) variation contributes to HD phenotype we genotyped 13 single nucleotide polymorphisms (SNPs) that define the major European mtDNA haplogroups in 404 HD patients. Genotype-dependent functional effects on intracellular ATP concentrations were assessed in peripheral leukocytes. In patients carrying the most common haplogroup H (48.3%), we demonstrate a significantly lower age at onset (AO). In combination with PGC-1 alpha genotypes, 3.8% additional residual variance in HD AO can be explained. Intracellular ATP concentrations in HD patients carrying the cytochrome c oxidase subunit I (CO1) 7028C allele defining haplogroup H were significantly higher in comparison to non-H individuals (mean +/- SEM, 599 +/- 51.8 ng/ml, n = 14 vs. 457.5 +/- 40.4 ng/ml, p = 0.03, n = 9). In contrast, ATP concentrations in cells of HD patients independent from mtDNA haplogroup showed no significant differences in comparison to matched healthy controls. Our data suggest that an evolutionarily advantageous mitochondrial haplogroup is associated with functional mitochondrial alterations and may modify disease phenotype in the context of neurodegenerative conditions such as HD.

Electrophoresis of DNA in human genetic diagnostics - state-of-the-art, alternatives and future prospects.

Electrophoretic separation of nucleic acids according to their molecular weights has dominated the methods' spectrum in molecular genetics for nearly half a century. We review the current methodological basis and evaluate its impact with special reference to new developments in the microarray technology. Although electrophoresis may be made redundant for many applications in DNA diagnostics within a few years, a number of electrophoretic vestiges will remain irreplaceable in the foreseeable future.