Archives SEEM

Kateryna Makova

Le 6 mars 2015 - Grande salle de réunion du CEFE - 11h30

 

The manifestation of mitochondrial DNA (mtDNA) diseases depends on the frequency of heteroplasmy (the presence of several alleles in an individual), yet its transmission across generations cannot be readily predicted owing to a lack of data on the size of the mtDNA bottleneck during oogenesis. For deleterious heteroplasmies, a severe bottleneck may abruptly transform a benign (low) frequency in a mother into a disease-causing (high) frequency in her child. Here we present a high-resolution study of heteroplasmy transmission conducted on blood and buccal mtDNA of 39 healthy mother-child pairs of European ancestry (a total of 156 samples, each sequenced at 20,000× per site). On average, each individual carried one heteroplasmy, and one in eight individuals carried a disease-associated heteroplasmy, with minor allele frequency ≥1%. We observed frequent drastic heteroplasmy frequency shifts between generations and estimated the effective size of the germ-line mtDNA bottleneck at only 30-35 (interquartile range from 9 to 141). Accounting for heteroplasmies, we estimated the mtDNA germ-line mutation rate at 1.3 × 10(-8) (interquartile range from 4.2 × 10(-9) to 4.1 × 10(-8)) mutations per site per year, an order of magnitude higher than for nuclear DNA. Notably, we found a positive association between the number of heteroplasmies in a child and maternal age at fertilization, likely attributable to oocyte aging. This study also took advantage of droplet digital PCR (ddPCR) to validate heteroplasmies and confirm a de novo mutation. Our results can be used to predict the transmission of disease-causing mtDNA variants and illuminate evolutionary dynamics of the mitochondrial genome.

Recent Publications:

Rebolledo-Jaramillo B, Su MS, Stoler N, McElhoe JA, Dickins B, Blankenberg D, Korneliussen T, Nielsen R, Holland MM, Paul IM, Nekrutenko A, Makova KD. (2014) Maternal Age Effect and Severe Germline Bottleneck in the Inheritance of Human Mitochondrial DNA. PNAS 2014 111 (43) 15474-15479

Kuruppumullage Don P, Ananda G, Chiaromonte F, Makova KD. 2013. Segmenting the human genome based on states of neutral genetic divergence. Proceedings of the National Academy of Sciences USA 110

(36): 14699-14704