Table 2.

Prescribed daily maintenance dose of warfarin and mean international normalized ratio in relation to CYP2C9 and VKORC1 single nucleotide polymorphisms with minor allele frequency ≥ 2% among Blacks: The Grady Coumadin Study, Atlanta, Georgia, 2005–2006.

Single nucleotide polymorphism	No.	Daily maintenance warfarin dose (mg)		International normalized ratio
		Mean (SD)	Median (IQR)	Mean (SD) at enrollment	Mean (SD) at 6 months	Mean (SD) at 1 year
CYP2C9*2
C/C	184	7.0 (4.5)	6.1 (4.6)	2.6 (1.1)	2.7 (1.5)	2.8 (1.5)
C/T	8	4.8 (1.6)	5.0 (2.0)	2.3 (0.58)	2.3 (0.61)	2.6 (0.93)
T/T	0	-	-	-	-	-
VKORC1 4719T>C
T/T	213	6.9 (4.5)	6.1 (4.5)	2.6 (1.1)	2.6 (1.4)	2.8 (1.4)
T/C	7	5.1 (2.0)	4.3 (3.9)	2.7 (0.71)	3.4 (1.7)	2.4 (0.38)
C/C	0	-	-	-	-	-
VKORC1–1639G> A
G/G	165	7.0 (3.8)	6.4 (3.9)	2.6 (1.1)	2.6 (1.6)	2.8 (1.5)
G/A	45	6.9 (6.5)†	5.0 (2.9)	2.5 (0.96)	2.7 (1.2)	2.6 (1.3)
A/A	6	2.9 (1.2)‡,§	2.5 (1.1)	2.7 (1.0)	2.3 (0.87)	2.1 (0.49)
VKORC1 6853G>C
G/G	116	7.2 (4.0)	6.4 (3.9)	2.5 (1.1)	2.6 (1.3)	2.7 (1.2)
G/C	62	6.4 (4.5)¶	5.0 (3.9)	2.7 (1.1)	2.5 (0.93)	2.8 (1.8)
C/C	29	6.5 (6.2)#	5.0 (4.4)	2.4 (0.79)	3.1 (2.3)	2.5 (1.0)
VKORC1 6915C>T
C/C	195	7.0 (4.7)	6.1 (4.6)	2.6 (1.1)	2.6 (1.5)	2.8 (1.4)
C/T	23	6.4 (2.2)	6.1 (2.6)	2.7 (1.1)	2.7 (1.2)	2.5 (1.2)
T/T	1	4.3 (0.0)	4.3 (0.0)	2.8 (0.0)	2.5 (0.0)	2.4 (0.0)
VKORC1 8773C>T
C/C	138	6.8 (4.7)	5.0 (3.6)	2.6 (1.0)	2.6 (1.6)	2.8 (1.4)
C/T	73	7.1 (4.2)	6.4 (5.0)	2.6 (1.1)	2.6 (1.2)	2.8 (1.6)
T/T	9	5.9 (2.9)	5.0 (4.1)	2.6 (1.3)	2.6 (0.97)	2.3 (0.81)

^†Wilcoxon-Mann–Whitney test, p = 0.02 between G/A and G/G genotypes for VKORC1–1639G>A.

^‡Wilcoxon-Mann–Whitney test, p = 0.001 between A/A and G/G genotypes for VKORC1–1639G>A.

^§Wilcoxon-Mann–Whitney test, p = 0.008 between A/A and G/A genotypes for VKORC1–1639G>A.

^¶Wilcoxon-Mann–Whitney test, p = 0.046 between G/C and G/G genotypes for VKORC1 6853G>C.

^#Wilcoxon-Mann–Whitney test, p = 0.03 between C/C and G/G genotypes for VKORC1 6853G>C.

IQR: Interquartile range; SD: Standard deviation.