Mitochondrial DNA sequences of familial (maternal vs. non-maternal) ALS cases in whole blood, platelets and white blood cells

To address the question of whether mtDNA mutations might play a role in familiar ALS (fALS), mtDNA was isolated from whole blood (WB), white blood cells (WBC) and platelets (PLT) from fALS patients and the mitochondrial genome was analyzed using a mtDNA resequencing array (Affymetrix MitoChip v2.0) that allows detection of low-level heteroplasmy in addition to the conventional homoplasmic or heteroplasmic mutations. We distinguished between fALS cases with a prominent maternal (mat) inheritance pattern and fALS cases that do not point to a maternal inheritance pattern (non-mat). As additional controls we compared our results to healthy age and sex matched individuals without any known neurodegenerative background. With this we are aiming to get a deeper insight into a possible role of mtDNA alterations acting as a disease modifier in a subgroup of ALS patients presenting with a maternal transmission of the disease. 184 MitoChips were performed in total. For each analysed group a n-number was included as follows (CTRL/ALS non-mat/ALS mant): whole blood (49/23/25), white blood cells (22/6/16), platelets (21/6/16). For the isolated cell types (PLT and WBC) freshly drawn EDTA blood was used to isolate the cell populations by differential centrifugation and cleaning up of the sample by magnetic bead separation. For whole blood samples one aliquot of frozen EDTA blood from the biobank was used.