Table 3.

Frequencies of clinically relevant DARC allele groups in African Americans

Proposed allele group name *							Population frequency
Designation	Trivial	Alleles †	ISBT working draft ‡	Traditional terminology §	Associated Phenotype	Observed (n)	Mean	95% CI ∥
FY*01	FY*A	FY*01:1 to FY*01:3	FY*01 or FY*A	FY*A	Fy(a+b−)	11	10%	5% – 18%
FY*02	FY*B	FY*02:1 to FY*02:4	FY*02 or FY*B	FY*B	Fy(a−b+)	10	9%	4% – 17%
FY*03	FY*B-67C	FY*03:1 to FY*03:2	FY*02N.01	FY*B-33¶	Fy(a−b−) **	81	75%	60% – 93%
FY*04	FY*B298A	FY*04:1	n/a	FY*B-298A	Fy(a−b+)	5	5%	2% – 11%
FY*05	FY*X	FY*05:1	FY*02M.01	FY*X	Fy(a−b+w)	1	1%	0.02% – 5%
Total						108

^*The alleles were grouped based on the nucleotide sequence in the exons and GATA box as detailed in the text. Allele terminology using FY instead of DARC according to the ISBT Working Party on Red Cell Immunogenetics and Blood Group Terminology (see footnote to Table 2).^30,31

^†Allele designation as defined in Table 2

^‡Current working draft of the new proposed ISBT terminology for blood group alleles¹⁸

^§Commonly used terminology as summarized by Castilho¹³

^∥95% confidence interval (CI) based on Poisson distribution

^¶This allele, which is not a DARC null allele, has also been designated Fy,² FY,⁹ Fy⁻,¹⁰ FY*Fy,³² FY*0,³³ FY*silent,³⁴ FY*−33C,³⁵ FY*−67C,³⁶ FY*B^ES,³⁷ FY*Bnull,³⁸ DARC-null³⁹ using various relative nucleotide positions to indicate the t>c polymorphism (−46,⁹ −365,¹⁰ −33,¹³ −67¹⁸) while the position −67 used in the new terminology is based on the fixed start of the CDS of NM_002036.2.

^**In contrast to rare DARC null alleles,¹³ the Fy^b antigen is expressed in non-erythroid tissues.