Biology Reference
In-Depth Information
Figure 1.10, cont'd
FY
*
B
, that vary based on a single base substitution (G125A) (
Zimmer-
man, 2004
;
Langhi and Bordin, 2006
). A separate single base substitution
in the gene's promoter region (T-33C) may block the expression of the
gene and result in a null 'erythrocyte silent' (ES) phenotype. This mutation
is most commonly associated with the
FY
*
B
(
FY
*
B
ES
) allele (the
FY
*
A
ES
allele is extremely rare) (
Langhi and Bordin, 2006
;
Sellami et al., 2008
).
These four alleles (
FY
*
A
,
FY
*
B
,
FY
*
B
ES
,
FY
*
A
ES
) result in 10 possible
genotypes and four possible phenotypes: Fy(a+b+), Fy(a+b−), Fy(a−b−)
and Fy(a−b−) (
Howes et al., 2011
). Methods to diagnose Duffy types can
focus on different aspects of the system: the individual polymorphic sites,
the genotype, the presence or absence of the antigen, and which particu-
lar type of antigen is being expressed. The assembled data were therefore
grouped into five types according to which diagnostic approach was used:
