Dataset Information

Maternal homocysteine in pregnancy and offspring birthweight: epidemiological associations and Mendelian randomization analysis.

ABSTRACT:

Background

Disturbed one-carbon (1-C) metabolism in the mother is associated with poor fetal growth but causality of this relationship has not been established.

Methods

We studied the association between maternal total homocysteine and offspring birthweight in the Pune Maternal Nutrition Study (PMNS, Pune, India) and Parthenon Cohort Study (Mysore, India). We tested for evidence of causality within a Mendelian randomization framework, using a methylenetetrahydrofolatereductase (MTHFR) gene variant rs1801133 (earlier known as 677C→T) by instrumental variable and triangulation analysis, separately and using meta-analysis.

Results

Median (IQR) homocysteine concentration and mean (SD) birthweight were 8.6 µmol/l (6.7,10.8) and 2642 g (379) in the PMNS and 6.0 µmol/l (5.1,7.1) and 2871 g (443) in the Parthenon study. Offspring birthweight was inversely related to maternal homocysteine concentration-PMNS: -22 g/SD [95% confidence interval (CI): (-50, 5), adjusted for gestational age and offspring gender]; Parthenon: -57 g (-92, -21); meta-analysis: -40 g (-62, -17)]. Maternal risk genotype at rs1801133 predicted higher homocysteine concentration [PMNS: 0.30 SD/allele (0.14, 0.46); Parthenon: 0.21 SD (0.02, 0.40); meta-analysis: 0.26 SD (0.14, 0.39)]; and lower birthweight [PMNS: -46 g (-102, 11, adjusted for gestational age, offspring gender and rs1801133 genotype); Parthenon: -78 g (-170, 15); meta-analysis: -61 g (-111, -10)]. Instrumental variable and triangulation analysis supported a causal association between maternal homocysteine concentration and offspring birthweight.

Conclusions

Our findings suggest a causal role for maternal homocysteine (1-C metabolism) in fetal growth. Reducing maternal homocysteine concentrations may improve fetal growth.

SUBMITTER: Yajnik CS

PROVIDER: S-EPMC4190518 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:High levels of plasma homocysteine occur almost uniformly in patients with end-stage renal disease (ESRD). IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis and a common cause of ESRD in young adults. Here, we aimed to detect whether homocysteine was elevated and associated with clinical-pathologic manifestations of IgAN patients and tested its causal effects using a two-sample Mendelian randomization (MR) approach. METHODS:For observational analysis, 108 IgAN patients, 30 lupus nephritis (LN) patients, 50 minimal change disease (MCD) patients, and 206 healthy controls were recruited from April 2014 to April 2015. Their plasma homocysteine was measured and clinical-pathologic manifestations were collected from medical records. For MR analysis, we further included 1686 IgAN patients. The missense variant methylenetetrahydrofolate reductase C677T (rs1801133) was selected as an instrument, which was genotyped by TaqMan allele discrimination assays. RESULTS:Majority of IgAN patients (93.52%, 101/108) showed elevated levels of plasma homocysteine (>10 ?mol/L). Plasma homocysteine in IgAN patients was significantly higher than that in MCD patients (median: 18.32 vs. 11.15 ?mol/L, Z?=?-5.29, P?<?0.01) and in healthy controls (median: 18.32 vs. 10.00 ?mol/L, Z?=?-8.76, P?<?0.01), but comparable with those in LN patients (median: 18.32 L vs. 14.50 ?mol/L, Z?=?-1.32, P?=?0.19). Significant differences were observed in sub-groups of IgAN patients according to quartiles of plasma homocysteine for male ratio (22.22% vs. 51.85% vs. 70.37% vs. 70.37%, ??=?14.29, P?<?0.01), serum creatinine (median: 77.00 vs. 100.00 vs. 129.00 vs. 150.00 ?mol/L, ??=?34.06, P?<?0.01), estimated glomerular filtration rate (median: 100.52 vs. 74.23 vs. 52.68 vs. 42.67 mL·min·1.73 m, ??=?21.75, P?<?0.01), systolic blood pressure (median: 120.00 vs. 120.00 vs. 125.00 vs. 130.00 mmHg, ??=?2.97, P?=?0.05), diastolic blood pressure (median 80.00 vs. 75.00 vs. 80.00 vs. 81.00 mmHg, ??=?11.47, P?<?0.01), and pathologic tubular atrophy and interstitial fibrosis (T) (T0/T1/T2: 62.96%/33.33%/3.70% vs. 29.63%/40.74%/29.63% vs. 24.00%/48.00%/28.00% vs. 14.81%/37.04%/48.15%, ??=?17.66, P?<?0.01). The coefficient of each rs1801133-T allele on homocysteine levels after controlling age and sex was 7.12 (P?<?0.01). MR estimates showed causal positive effects of homocysteine on serum creatine (??=?0.76, P?=?0.02), systolic blood pressure (??=?0.26, P?=?0.02), diastolic blood pressure (??=?0.20, P?=?0.01), and pathologic T lesion (??=?0.01, P?=?0.01) in IgAN. CONCLUSIONS:By observational and MR analyses, consistent results were observed for associations of plasma homocysteine with serum creatinine, blood pressures, and pathologic T lesion in IgAN patients.