The MTHFR 677T Allele May Influence the Severity and Biochemical Risk Factors of Alzheimer’s Disease in an Egyptian Population

Table 4

Distribution of MTHFR 677C>T genotypes and their allelic frequencies in Alzheimer’s cases and controls from different ethnic populations.

Country (population)^a; [Reference]	No. of cases; (no. of controls)	Distribution of rs1801133 SNP genotypes^b			Frequency of T allele
		C/C	C/T	T/T
Poland (Caucasian) [20]	99 (100)	53.5 (55.0)	38.4 (38.0)	8.1 (7.0)	27.3^c (26.0)
Iran (others) [21]	117 (125)	48.7 (67.2)	37.6 (26.4)	13.7 (6.4)	32.5^d (19.6)
N. Ireland (Caucasian) [22]	83 (71)	71.1 (70.4)	24.1 (26.8)	4.8 (2.8)	33.7^d (16.2)
China (East Asia) [23]	104 (100)	48.1 (60.8)	36.5 (36.2)	15.4 (3.0)	33.7^d (21.2)
Brazil (others) [24]	30 (29)	36.7 (51.7)	56.7 (37.9)	6.6 (10.4)	35.0^d (29.7)
Egypt  (current study)	43  (32)	41.9  (62.5)	39.5  (31.2)	18.6  (6.3)	38.4 ^c  (21.9)
China (East Asia) [25]	105 (102)	37.1 (33.3)	42.9 (48.0)	20.0 (18.7)	41.4^c (42.6)
United States (Caucasian) [26]	124 (97)	33.0 (38.0)	50.5 (59.9)	16.5 (11.1)	41.8^c (36.5)
Japan (East Asian) [27]	194 (379)	33.0 (38.0)	50.5 (50.9)	16.5 (11.1)	41.8^c (36.5)
Israel (others) [28]	49 (40)	24.5 (37.5)	63.3 (40.0)	12.2 (22.2)	45.7^c (42.5)
Italy (Caucasian) [29]	231 (137)	27.7 (28.5)	52.0 (47.4)	20.3 (24.1)	46.3^c (47.8)
China (East Asian) [30]	386 (375)	46.4 (24.0)	32.4 (45.9)	44.4 (30.1)	55.6^c (53.1)
Sweden (Caucasian) [31]	204 (172)	48.0 (48.3)	44.1 (39.5)	7.9 (12.2)	59.8 (32.0)
Korea (East Asian) [32]	86 (625)	12.8 (19.5)	50.0 (53.1)	37.2 (27.4)	62.2^c (53.9)

Abbreviations. AD: Alzheimer’s disease, SNP: single nucleotide polymorphism.
^aPopulations are arranged in ascending order of the frequency of the T alleles in Alzheimer’s cases.
^bGenotype distributions of AD cases, with distributions of controls in parentheses.
^cThe distribution of the MTHFR 677T allele does not differ between Alzheimer’s cases and controls (P > 0.05).
^dThe distribution of the MTHFR 677T allele is significantly different between Alzheimer’s cases and controls (P < 0.05).