TABLE 9

Relationship between DARC genotype, phenotype, and P. vivax infectionf

DARC genotypeaRed cell phenotypeDosage of DARCbPvDBP bindingcClinical infectiond
Relative risk95% CI
FY*A/FY*BES Fy(a+b−)+∼2.0 × 104 0.2040.09–0.87
FY*A/FY*A Fy(a+b−)++∼4.5 × 104 0.7150.31–1.21
FY*A/FY*X Fy(a+bw)e +NDND
Fy(a+b−)e
FY*A/FY*B Fy(a+b+)++∼5.8 × 104 1.00
FY*B/FY*B Fy(a−b+)++∼7.2 × 104 2.701.36–5.79
FY*B/FY*X Fy(a−b+)+NDND
FY*B/FY*BES Fy(a−b+)+ND2.170.91–4.77
FY*X/FY*BES Fy(a−bw)e wNDNDResistant to blood-stage infection (?)
Fy(a−b−)e
FY*BES /FY*BES Fy null00 Resistant to blood-stage infection
  • a FY*A, DARC allele carrying the Fya antigen; FY*B, allele carrying the Fyb antigen; FY*X, allele encoding weak Fyb expression on all tissues; FY*BES , Fy-null allele carrying a GATA promoter mutation leading to a loss of DARC expression on red cells only (ES, erythroid silent).

  • b Relative dose of DARC glycoprotein (+, 1 copy; ++, 2 copies; w, very weak [5% of normal]) on red cells based on genotype.

  • c Binding of recombinant PvDBPII to human red cells (mean fluorescence intensity × percent positive red cells) by DARC genotype. Data are estimates based on graphed data reported by King et al. (515).

  • d Relative risk of clinical P. vivax infection in the Brazilian Amazon by DARC genotype (515).

  • e FY*X red cells can be serologically typed as Fy(b−) or Fy(bw) due to very weak Fyb expression (5% of normal).

  • ND, not done.