The 89th Annual Meeting of the American Association of Physical Anthropologists (2020)

How HbAS and HbAC heterozygotes manifest their differences from HbAA individuals at the hemogram level


1Anthropology, University of South Florida, 2Educacion, Instituto Federal de Educação, Ciência e Tecnologia do Tocantins, Araguaína, 3Instituto de Ciências Biológicas, Universidade de Brasília, 4Instituto de Ciências Biológicas, Universidade de Brasília

April 17, 2020 , Platinum Ballroom Add to calendar

Flansburg et al. (2019) demonstrated that sickle cell (HBAS) heterozygotes have diverse clinical expressions depending on SNPs affecting production of fetal hemoglobin (HBF) in a sample from the USA. The purpose of the current project is to determine if HbF is also associated with HBAS or HBAC phenotypes in three Afro-Brazilian communities known as Quilombos, each with different historical backgrounds. All of them are from the Central Brazilian states of Goías and Tocantins. We found substantial population structure, where all HBAC heterozygotes were sampled in the third Quilombo. Unexpectedly, HbF was absent in any HBAS (n=12) or HbAC (n=11) individuals, but found in only 17 HBAA individuals, whose HBF percent ranged from 0.3 to 1.3%. Amato et al. (2012) notes that increased levels of HBF are observed in some mild β-thalassemic patients. These results may suggest that 17 HBAA individuals with elevated HBF may be thalassemic and will now test them for it. Results of a Kruskal-Wallis-two-sided test indicated that these four hemoglobin groups (HBAA, HBAA+HBF, HBAS, HBAC) were significantly differences in their hematocrit (X2=17.58,df=3,p<0.0005), mean cell hemoglobin (X2=15.8,df=3,p<0.001), and mean cell hemoglobin concentration (X2=20.8519,df=3,p<0.0001). Results of this study provide one more window into how and why some HbAS and even HbAC individuals show some clinical manifestations of their heterozygosity. We demonstrate the importance of working with human groups of different evolutionary histories. Not only are African-USA-derived groups different from Afro-Brazilian group, but within a region of Brazil there is population structure which affects the distribution of these alleles.

Slides/Poster (pdf)