Immunity to disease may vary depending on ethnicity so designing treatments that will work for everybody may be impossible, U.S. and Canadian researchers say.

DNA sequencing suggests human antibody genes and how well they operate -- and what they can fight off -- can vary from person to person, and ethnicity may influence immunity, a release from Simon Fraser University in British Columbia reported.

The researchers say the finding is based on sequencing the immensely repetitive DNA in the human genome's 1 million nucleotide-long immunoglobulin heavy (IGH)-chain locus -- long known as the most prolific producer of the 50-plus varied and diverse antibody-encoding genes that cells use to fight off infections and diseases.

"Time will confirm the extent to which this is true. But we've found that sections of the IGH-chain locus' DNA sequence are either missing or inserted into a person's genome, and this could vary depending on ethnicity," Corey Watson, a postdoctoral researcher at the Mount Sinai School of Medicine in New York, said.

That may affect the effectiveness of drugs, treatments and vaccinations usually designed to treat whole populations. The researchers said the link between antibody makeup and ethnicity surfaced when they screened the chromosomes of 425 people of Asian, African and European descent for several DNA insertions and deletions.

The findings "could mean that past environmental exposures to certain pathogens caused DNA insertions or deletions in different ethnic groups, which could impact disease risk," Watson said. "Our results demonstrate that antibody studies need to take into account the ethnicity of DNA samples used."