In a 2021 American Family Physician editorial on the dangers of incorporating a patient’s race into medical decision-making, Dr. Bonzo Reddick observed, “Although we may hear about biologic or genetic differences between races, there is more variation within races than there is between them.” A recent landmark report from the National Institutes of Health’s All of Us Research Program compared self-identified race and ethnicity categories to continental and subcontinental genetic variation. Analyzing about 2 million common variants in the genomes of more than 230,000 unrelated participants, they found that “participants within self-identified race and ethnicity groups exhibit gradients of genetic variation rather than discrete clusters.”
Among White participants, 8% were found to have some South Asian ancestry, whereas smaller percentages had more than 50% African or Native American ancestry. Similarly, 1 in 100 self-identified Black participants had more than 50% European ancestry. The study also found notable regional differences in ancestry percentages among self-identified Black, Hispanic, and White participants. The researchers concluded that these gradients reflect “the historical impacts of US colonization, the transatlantic slave trade, and recent migrations” and “demonstrate that social constructs of race and ethnicity do not accurately reflect underlying genetic variation.”
Maternal race—specifically, Black race—is associated with increased risk for the development of preeclampsia. In its 2021 recommendation statement on aspirin to prevent preeclampsia and related morbidity and mortality, the US Preventive Services Task Force included Black race as a moderate risk factor, although it noted that it was a proxy for “environmental, social, and historical inequities, … not biological propensities.” However, a multicenter cohort study in JAMA Network Open found that Black race, similar to other moderate risks such as nulliparity, maternal age older than 35 years, and body mass index above 30, was not clearly associated with preeclampsia in the absence of a high risk factor (eg, chronic hypertension).
Finally, a narrative article in the New England Journal of Medicine traced the historical debate over race-based hemoglobin thresholds that began in the 1970s, when epidemiologic analyses showed that on average, Black children’s serum hemoglobin levels were 0.5 g/dL lower than those of White children. Did this disparity reflect inherent biological differences between races or differences in nutrition? Should it support race-based definitions of normal hemoglobin levels? Although some analyses accounting for socioeconomic status and diet no longer found significant racial differences, conflicting guidance from the Institute of Medicine (now the National Academy of Medicine) and the Centers for Disease Control and Prevention persisted into the early 2000s. Today, the World Health Organization, American Academy of Pediatrics, and American College of Obstetricians and Gynecologists all recommend against using race-adjusted cutoffs for diagnosing anemia.
