Mitochondrial and Nuclear Ancestry Association to PTB

Genome-wide genotyping studies of cohorts of preterm and term individuals were evaluated. Mitochondrial haplogroup and nuclear ancestry for individuals were determined and used to develop a scoring for the degree to which mitochondrial ancestry is divergent from nuclear ancestry. Infants with higher degrees of divergent mitochondrial ancestry were at increased risk for preterm birth (0.124 for preterm vs 0.105 for term infants; P < .05). This finding was validated in 1 of 2 replication cohorts. Greater degrees of divergent ancestry correlating with earlier delivery within the primary study population was observed, but this finding was not replicated in secondary cohorts born preterm. Individuals with divergent patterns of mitochondrial and nuclear ancestry are at increased risk for preterm birth. These findings may in part explain the higher rates of preterm birth in African Americans and in individuals with a matrilineal family history of preterm birth.