Self-Assessment of Color Categories and Its Relationship with HLA Profiling in Brazilian Bone Marrow Donors

• We analysed self-assessed skin colour and HLA profiles from bone marrow donors.
• We evaluated the data of 71,291 bone marrow donors from Brazil.
• We found that HLA itself was a better ancestry indicator than self-assessed colour.
• Especially in highly admixed populations such as that of Brazil.

The Brazil Ministry of Health maintains a Registry of Bone Marrow Donors that corresponds to approximately 12% of the Bone Marrow Donors Worldwide registry. This registry contains information on ethnicity (by self-assessment of color) and HLA-A, -B, and -DRB1 type. The self-assessment of color tool has been extensively used for admixed population characterization. In this context, Brazil represents a highly admixed population, resulting from 5 centuries of colonization and interbreeding, mainly, but not exclusively, among Native Americans, Europeans, and Africans. Here we evaluated self-assessed skin color and HLA genetic information from 71,291 bone marrow donors of southern Brazil to verify how likely is the HLA profiling correspondence within and between self-assessed color groups. We found that HLA itself was a better ancestry indicator than was self-assessed color. Therefore, self-assessment of color in highly admixed populations, such as that of Brazil, is not indicative of higher correspondence in the HLA profiles within skin color groups.