Genetic Ancestry Has the Same Major Problems as Phenotypic Ancestry

To the Editor:

Using genetic scores to identify ethnic background (1) is more precise but no different in principle from using physical characteristics and carries the same hazards for the misuse of “race” as a variable in medicine. Skin tone is largely inherited, and even among African Americans it is associated with educational level, income, and employment either as a manager or professional (2, 3). Nobody would believe that these indicators of social advantage are genetically determined. Using genotyping to “improve” the determination of what social position an individual ought to aspire to would horrify most people; its use to determine what lung function an individual should expect should also raise alarm. Using specific genes that may explain lung function would be useful and doesn’t have the same problem, though the information may still be abused. However, where specific genes are known there is no longer any need to know the “% African” inheritance or any other information on ethnicity. This is the logic that supports the screening of neonates for sickle cell genotypes without regard to reported ethnicity. Unfortunately, there has still been relatively little success in identifying the genes that are believed from family studies to explain around 50% of the variation in lung function. Until this situation improves, genes are of limited use in interpreting lung function.