Researchers discovered surprising differences in the metabolism profiles of healthy American babies, which may help make screening for inherited metabolic disorders, cystic fibrosis, or hypothyroidism much more accurate than traditional genetic disease screens.
“We don’t want to miss a baby who could be sick, and we don’t want to burden families with the burdens and concerns that a false-positive test can cause,” said Curt Scharfe, associate professor of genetics at Yale School of Medicine and senior author of the study published in the journal Molecular Genetics and Metabolism.
Scharfe and colleagues analysed data from over 400,000 babies from 17 self-reported ethnic groups who were part of California’s newborn screening programme for the study. They wanted to know if these ethnic differences could be detected in metabolites, molecules found in infant blood that provide energy by breaking down food or body tissue such as fat.
The question was of academic interest as well as concern to paediatricians. For example, babies of African ancestry are more likely to have elevated blood biomarkers indicating cystic fibrosis than babies born to white parents, despite the fact that babies born to white parents are far more likely to develop the disease.
Researchers believe that using ancestry to interpret differences in marker levels will provide more accurate risk assessments than traditional genetic tests.
Because they are descendants of the world’s oldest ancestral population, people of African descent have higher genetic diversity than those from other ethnic groups. Modern humans migrated from Africa to regions all over the world; other ethnic groups are descended from these original migrants and have enough genetic variation to be genetically identifiable.
The researchers discovered that metabolic lineages can tell a different story. For example, while genetic differences between African-Americans and Americans of European descent are clear, researchers discovered that these two groups are metabolically more similar.
In contrast, while people of Japanese and Chinese descent are genetically related, the researchers discovered larger differences in their metabolic profiles.
“This demonstrates the importance of our environment in shaping our metabolism,” Scharfe said. “Where people share the same culture and food, metabolic profiles are more similar; where people are separated by circumstances, such as language or lifestyle, metabolic differences outweigh genetic differences.”
Scharfe warns that more research is needed before the findings can be applied clinically. Researchers only looked at 41 metabolites out of hundreds, and they relied on parents’ reports of their ethnic heritage, which may not always be accurate.
“This is just the beginning,” Scharfe said, “but understanding our metabolic ancestors has a bright future.”