Methylenetetrahydrofolate reductase gene polymorphisms are not associated with embryo chromosomal abnormalities and IVF outcomes

Figures & data

Figure 1. Study design. Flowchart describing the number of samples in the different groups included in the study. As shown, the study group 3 is a subset of the study group 2

Table 1. Patient characteristics and biochemical and stimulation variables

Variable	Mean	Standard deviation
Age	37.0	5.9
Antral follicle count	13.5	7.2
Basal FSH (mIU/mL)	7.6	8.1
AMH (pmol/L)	16.7	11.0
Homocysteine (mmol/L)	7.6	2.3
No. of stimulation days	10.0	1.7
Total dose of gonadotropins (IU)	2488	863
No. of oocytes retrieved	13.4	7.2
No. of MII retrieved	10.7	5.5

Table 2. Genotype frequencies compared with 1000 Genomes Project (Phase 3) European population

MTHFR Polymorphism	Genotype	Frequency	European population frequency	P value
C677T	CC	0.33	0.40	0.256
	CT	0.52	0.46	0.385
	TT	0.15	0.14	0.722
A1298C	AA	0.44	0.48	0.597
	AC	0.45	0.42	0.688
	CC	0.11	0.10	0.827

P values are calculated with the Fisher’s Exact test.

Table 3. Comparison of aneuploidy and mosaicism rates in embryos (n = 191) according to maternal MTHFR genotype

	Maternal genotype MTHFR C677T			Maternal genotype MTHFR A1298C
	CC	CT/TT	P value	AA	AC/CC	P value
Embryo aneuploidy rate	54.7%	30.2%	0.058	37.8%	42.7%	0.212
Embryo mosaicism rate	24.0%	13.8%	0.345	17.1%	17.3%	0.865

P values are calculated with a binary logistic regression statistical test using as confounding factors maternal age, PGT-A technique and embryo quality (p < 0.05 is considered significantly different).

Table 4. Comparison of aneuploidy and mosaicism rates in embryos (n = 409) according to their MTHFR genotype

	Embryo genotype MTHFR C677T			Embryo genotype MTHFR A1298C
	CC	CT/TT	P value	AA	AC/CC	P value
Embryo aneuploidy rate	22.3%	15.7%	0.464	17.9%	18.3%	0.988
Embryo mosaicism rate	13.5%	5.4%	0.019*	7.5%	9.1%	0.817

P values are calculated with a binary logistic regression statistical test using as confounding factors maternal age, PGT-A technique and embryo quality (p < 0.05 is considered significantly different).

Figure 2. C677T and A1298C MTHFR genotype frequencies in the 1000 Genomes Project (Phase 3) European population, female patients and embryos. A) C677T genotypes. B) A1298C genotypes. Fisher’s exact test was used to compare genotype frequencies in patients and embryos with the European population frequencies

Table 5. IVF outcomes for single euploid embryo transfers according to different C677T/A1298C MTHFR genotypes in transferred embryos (n = 241)

	MTHFR C677T			P value		MTHFR A1298C			P value		MTHFR C677T/A1298C		P value
	CC	CT	TT	P P^1		AA	AC	CC	P P^1		677CC 1298AA	677CT/TT 1298AC/CC
		CT/TT		P^2			AC/CC		P^2
Pregnancy rate	54.1%	50.8%	55.3%	0.887	0.448	47.3%	60.0%	53.3%	0.023	0.743	43.5%	53.7%	0.360
		52.1%		0.770			59.1%		0.050
Biochemical miscarriage rate	9.5%	8.3%	10.6%	0.438	0.460	7.6%	12.6%	0.0%	0.098	0.999	0.0%	10.1%	0.998
		9.0%		0.943			10.9%		0.372
Implantation rate	44.6%	42.5%	44.7%	0.912	0.929	39.7%	47.4%	53.3%	0.304	0.332	43.5%	43.6%	0.825
		43.1%		0.669			48.2%		0.201
Clinical miscarriage rate	6.1%	7.8%	9.5%	0.703	0.447	5.8%	11.1%	0.0%	0.288	0.999	0.0%	8.4%	0.999
		8.3%		0.484			9.4%		0.539
Ongoing pregnancy rate	41.9%	39.2%	40.4%	0.982	0.934	37.4%	42.1%	53.3%	0.427	0.282	43.5%	39.9%	0.618
		39.5%		0.611			43.6%		0.276

P values are calculated with a logistic regression statistical test using as confounding factors embryo quality and oocyte origin (p < 0.05 is considered significantly different). P refers to CT vs. CC (in C677T genotype), AC vs. AA (in A1298C genotype) and 677CT/TT 1298AC/CC vs. 677 CC/1298AA (in C677T/1298C combined genotype). P¹ refers to TT vs. CC (in C677T genotype), CC vs. AA (in A1298C genotype). P² refers to CT/TT vs. CC (in C677T genotype), AC/CC vs. AA (in A1298C genotype).