SELF-REPORTED RACE EXPLAINS ONE-THIRD OF THE VARIABILITY IN AFRICAN GENETIC ANCESTRY AMONG BRAZILIAN PATIENTS WITH SICKLE CELL DISEASE

@article{moura2026selfreported,
  title = {{SELF-REPORTED RACE EXPLAINS ONE-THIRD OF THE VARIABILITY IN AFRICAN GENETIC ANCESTRY AMONG BRAZILIAN PATIENTS WITH SICKLE CELL DISEASE}},
  author = {Isabel Cristina Gomes MOURA and Carla Luana DINARDO and Mina Cintho OZAHATA and Sheila MATEOS and Márcio OIKAWA and Alessandra FERRAZ and Luiz AMORIM and André BELISáRIO and Anna Bárbara PROIETTI and Shannon KELLY and Brian CUSTER and Vanderson ROCHA},
  journal = {Hematology, Transfusion and Cell Therapy},
  year = {2026},
  month = oct,
  doi = {10.1016/j.htct.2026.106704},
  url = {https://doi.org/10.1016/j.htct.2026.106704},
  note = {CC BY},
}

TY  - JOUR
TI  - SELF-REPORTED RACE EXPLAINS ONE-THIRD OF THE VARIABILITY IN AFRICAN GENETIC ANCESTRY AMONG BRAZILIAN PATIENTS WITH SICKLE CELL DISEASE
AU  - Isabel Cristina Gomes MOURA
AU  - Carla Luana DINARDO
AU  - Mina Cintho OZAHATA
AU  - Sheila MATEOS
AU  - Márcio OIKAWA
AU  - Alessandra FERRAZ
AU  - Luiz AMORIM
AU  - André BELISáRIO
AU  - Anna Bárbara PROIETTI
AU  - Shannon KELLY
AU  - Brian CUSTER
AU  - Vanderson ROCHA
PY  - 2026
DA  - 2026/10/23
JO  - Hematology, Transfusion and Cell Therapy
DO  - 10.1016/j.htct.2026.106704
UR  - https://doi.org/10.1016/j.htct.2026.106704
AB  - Background: Self-reported race is commonly used as a surrogate for genetic ancestry in sickle cell disease (SCD) research, although it represents a social construct rather than a biological measure. The extent to which self-reported race reflects individual African genetic ancestry remains uncertain in highly admixed populations such as Brazilian population. Aims: To evaluate the relationship between self-reported race and African genetic ancestry in Brazilian patients with sickle cell disease (HbSS/HbSβ⁰-thalassemia). Methods: This real-world multicenter study included patients with HbSS or HbSβ⁰-thalassemia enrolled in the REDS-III Brazil SCD cohort who had available genetic ancestry estimates. Individuals self-identifying as White, Mixed, or Black were compared regarding African (AFR), European (EUR), and Native American (NAM) ancestry proportions. Group differences were assessed using the Kruskal-Wallis test. The association between self-reported race and African genetic ancestry was quantified using linear regression with heteroscedasticity-consistent (HC3) robust standard errors. Adjusted marginal means and pairwise comparisons were estimated using the emmeans package with Holm correction. Results: A total of 1,850 SCD patients were included: 190 (10.3%) self-identified as White, 1,112 (60.1%) as Mixed, and 548 (29.6%) as Black individuals. African genetic ancestry increased progressively across self-reported racial groups, whereas European ancestry showed the opposite pattern. NAM ancestry also differed significantly among groups but accounted for only a small proportion of the overall genetic background (all global p<0.001). Adjusted mean African ancestry was 28.9% (95% CI, 27.0–30.8) among White individuals, 42.9% (95% CI, 42.0–43.8) among Mixed individuals, and 64.0% (95% CI, 62.6–65.4) among Black individuals. All pairwise comparisons were statistically significant between all racial groups (Black vs. White: +35.1 percentage points; Black vs. Mixed: +21.1 percentage points; Mixed vs. White: +14.0 percentage points; all Holm-adjusted p<0.001). Despite this clear gradient, self-reported race explained 35.5% of the variability in African genetic ancestry (adjusted R²=0.355), indicating substantial overlap in ancestry distributions among the three racial groups. Discussion and Conclusions: Among Brazilian patients with SCD, self-reported race was strongly associated with African genetic ancestry, demonstrating a progressive increase in African ancestry from White to Mixed to Black individuals. However, self-reported race explained only approximately one-third of the variability in African genetic ancestry, highlighting the marked genetic heterogeneity within each racial group. These findings show that self-reported race and genetic ancestry capture are related but distinct dimensions. While self-reported race remains an important demographic and epidemiologic variable it should not be considered an accurate surrogate for individual genetic ancestry in clinical or epidemiological studies.
SN  - 2531-1379
SN  - 2531-1387
ER  -