Cord‑blood mtDNA link to childhood obesity
Researchers reported that higher mitochondrial DNA heteroplasmy in cord blood is associated with roughly a 46% higher risk of childhood obesity, with the effect strongest in girls and peaking in adolescence. (x.com) The finding suggests early‑life mitochondrial markers could help explain who faces greater obesity risk later in childhood. (x.com)
Mitochondria are the parts of cells that turn food into energy, and each one carries its own small set of DNA. A study published April 14 found that some newborns with a mix of mitochondrial DNA versions in cord blood later had higher odds of overweight or obesity in childhood. (nature.com) The study tracked 952 children in the Boston Birth Cohort from birth and compared cord-blood mitochondrial DNA markers with repeated body-mass measurements over time. The researchers defined overweight or obesity as a body mass index at or above the 85th percentile for age and sex using U.S. reference data. (pubmed.ncbi.nlm.nih.gov) The marker in question is called heteroplasmy, which means a person carries more than one mitochondrial DNA sequence at the same time. In girls, newly arising heteroplasmic variants in functional coding regions were linked to a 46% higher risk of childhood overweight or obesity and a higher body mass index z score. (pubmed.ncbi.nlm.nih.gov) The signal did not appear across the full sample overall, and the paper said the association was strongest in girls ages 10 to 18. The authors also measured mitochondrial DNA copy number, a count of how many mitochondrial genomes are present, and found that its relationship with body mass index changed depending on whether heteroplasmy was present. (nature.com) That makes this a study about early-life metabolic programming, the idea that biology around birth can shape later health. The paper said it is the first prospective study to examine cord-blood mitochondrial DNA heteroplasmy and copy number together in relation to childhood overweight or obesity. (nature.com) The finding also lands in a field that has been building piece by piece rather than all at once. A 2024 study in the *International Journal of Obesity* linked one cord-blood mitochondrial heteroplasmy variant to rapid infant growth and to overweight at ages 4 to 6 in a cohort of 200 mother-child pairs. (nature.com) Scientists have studied heteroplasmy for years because mitochondria have their own DNA and because mixed mitochondrial DNA populations can affect how cells make energy. Reviews describe heteroplasmy as the presence of two or more mitochondrial DNA types in one person, often arising from mutations over time or being passed down maternally. (ncbi.nlm.nih.gov) The new paper does not show that cord-blood mitochondrial changes cause obesity, only that they were associated in this cohort. Its next use, if the result holds up in other populations, would be as an early-life risk marker rather than a diagnosis. (pubmed.ncbi.nlm.nih.gov)
