Estimates of West African Ancestry in African Americans Using Alleles of Iron-Related Genes HJV , SLC40A1 , and TFR2 .

Background: Few studies have estimated African ancestry of African Americans (AA). In sub-Saharan West African (WA) Blacks, some nonancestral alleles of iron-related genes HJV , SLC40A1 , and TFR2 are common, whereas in European Americans (EA) the same alleles are rare. These alleles have not been used to estimate WA Black ancestry in AA. Methods: We estimated WA Black ancestry in AA ( M ) using published HJV c.929C>G (rs7540883), SLC40A1 c.744G>T (rs11568350), and TFR2 c.713C>T (rs34242818) allele frequencies in WA Blacks, AA, and EA. We computed standard error (SE) and one-sided 95% confidence intervals (CI) for each M . Results: The combined representation of WA Blacks from The Gambia and Nigeria was 79-89%. Aggregate HJV , SLC40A1 , and TFR2 allele frequencies in WA Blacks were 0.1025 [95% CI: 0.0835-0.1253] ( n  = 405), 0.0517 [0.0469-0.0569] ( n  = 3839), and 0.1432 [0.1202-0.1697] ( n  = 405), respectively. Aggregate HJV , SLC40A1 , and TFR2 allele frequencies in AA were 0.0718 [0.0648-0.0797] ( n  = 2352), 0.0557 [0.0506-0.0613] ( n  = 3590), and 0.1224 [0.1132-0.1322] ( n  = 2352), respectively. Aggregate HJV , SLC40A1 , and TFR2 allele frequencies in 4449 EA were 0.0002 [0-0.0009], 0.0003 [0.0001-0.0010], and 0.0004 [0.0001-0.0012], respectively. M (SE [one-sided 95% CI]) for HJV , SLC40A1 , and TFR2 alleles was 0.7006 (0.0818 [0.5402-1.0000]), 1.0000 (0.0752 [0.9306-1.0000]), and 0.8546 (0.0810 [0.6959-1.0000]), respectively. Mean of these M is 0.8777 (87.8%). Conclusions: The mean proportional WA Black ancestry in AA of 87.8% using HJV c.929C>G, SLC40A1 c.744G>T, and TFR2 c.713C>T allele frequencies is consistent with that of previous studies that used other autosomal markers and methods.