Methylenetetrahydrofolate reductase 677 T allele protects against persistent HBV infection in West Africa.

BACKGROUND/AIMS: Homocysteine metabolism is linked to DNA methylation, a mechanism potentially involved in the course of hepatitis B virus (HBV) infection. We evaluated the association of determinants of homocysteine metabolism with the outcome of HBV infection. METHODS: Four hundred and fifty-five healthy adults from Togo and Benin were tested for HBV serologic markers, HLA DR alleles, folate, vitamin B12, methylenetetrahydrofolate reductase (MTHFR) 677 C-->T, 1298 A-->C and methionine synthase 2756 A-->G polymorphisms. RESULTS: Seventy-eight percent of the study population was anti-HBc positive. Among them, 202 (56.9%) were anti-HBs positive and 58 (16.3%) were HBsAg positive. After stepwise logistic regression, the MTHFR 677 T allele was independently associated with persistence of detectable anti-HBs antibodies (OR: 2.47; 95% CI: 1.29-4.71; p=0.006). The mean HBV DNA level was significantly lower in HBsAg positive subjects carrying the 677 T allele than in those with the 677 CC genotype (1000+/-1406 vs. 2,400,000+/-214,000 copies/ml, p=0.005). Beninese origin and HLA-DRB1*09 allele were the other determinants independently associated with favorable outcome of HBV infection. CONCLUSIONS: The methylenetetrahydrofolate reductase 677 T allele seems to protect against chronic HBV infection in young African adults.

Low frequency of mutated methylenetetrahydrofolate reductase 677C-->T and 1298A-->C genetics single nucleotide polymorphisms (SNPs) in Sub-Saharan populations.

5,10-Methylenetetrahydrofolate reductase (MTHFR) and methionine synthase (MTR) are two of the key enzymes in the folate/vitamin B12-dependent remethylation of homocysteine to methionine. The frequencies of MTHFR single nucleotide polymorphisms (SNPs), 677C-->T, 1298A-->C, 1317T-->C and of MTR, 2756A-->G, have been widely studied in Caucasians, but they have never been reported simultaneously in a large population from Sub-Saharan Africa. Presently, we report the prevalence of these SNPs and their relationship to homocysteine in 240 subjects recruited in West Africa. The frequencies of the mutant genotypes 677TT (0.8%) and 1298CC (2%) were lower than that usually observed in Caucasians, while the frequency of the mutant 1317CC was higher (16%). We formed a systematic association of the mutated MTHFR 677C-->T SNP with a 1298A/1317T common haplotype. The MTHFR mutant genotype 677TT was associated with an intermediate hyperhomocysteinemia (92.4 +/- 6.0 micromol/l) higher than that described in Caucasians. The 2756A-->G SNP in the MTR was similarly distributed in Africans compared to Caucasians. In conclusion, the MTHFR 677TTor 1298CC genotypes are much rarer in Africans than in Caucasians. The 677TT low frequency may be related to the high effect of this mutation on homocysteine metabolism in the environmental conditions of this African region.

Serum concentrations of sex hormone binding globulin are elevated in kwashiorkor and anorexia nervosa but not in marasmus.

BACKGROUND: Customary blood protein markers for malnutrition are of limited value in the diagnosis of protein-energy malnutrition or anorexia nervosa in children and in the follow-up to refeeding in such children. OBJECTIVES: For these diseases, we compared the diagnostic value of sex hormone binding globulin (SHBG) with that of albumin, transferrin, transthyretin, and retinal binding protein and determined the relations between concentrations of insulin, insulin-like growth factor I, and SHBG. DESIGN: SHBG was assayed in children with protein-energy malnutrition (29 children with kwashiorkor and 28 with marasmus), in 29 anorectic girls (before and after refeeding), and in age- and sex-matched control subjects. RESULTS: Mean (+/-SE) serum SHBG concentrations were higher in the children with kwashiorkor (0.18 +/- 0.07 micromol/L) than in the children with marasmus (0.11 +/- 0.05 micromol/L, P < 0.0001) or the control subjects (0.11 +/- 0.03 micromol/L, P < 0.0005). In the children with anorexia nervosa before weight gain, serum SHBG concentrations were significantly higher (0.10 +/- 0.04 micromol/L) than in the age-matched control subjects (0.06 +/- 0.03 micromol/L, P < 0.001) and decreased significantly after 30 d of refeeding (0.04 +/- 0.01 micromol/L, P < 0.0001). This decrease was negatively correlated with insulin-like growth factor I but not with insulin. Mean serum SHBG concentrations were influenced neither by inflammation, as indicated when C-reactive protein was used as a marker (0.27 +/- 0.27, 0.34 +/- 0.42, and <0.04 micromol/L in the children with marasmus, kwashiorkor, and anorexia nervosa, respectively), nor by glomerular filtration, as indicated when cystatin-C was used as a marker (68.46 +/- 23.08, 66.90 +/- 43.08, and 49.23 +/- 7.69 micromol/L, respectively). CONCLUSIONS: The high SHBG concentration observed in anorexia nervosa and kwashiorkor seems to be of multifactorial origin. For these 2 diseases, SHBG is a reliable marker of nutritional status, is unrelated to either C-reactive protein or cystatin-C, and may be helpful in distinguishing kwashiorkor from marasmus and as a follow-up marker after refeeding.

Hyperhomocysteinemia is related to a decreased blood level of vitamin B12 in the second and third trimester of normal pregnancy.

Hyperhomocysteinemia has been associated with several pregnancy complications. We have investigated the variation of plasma total homocysteine (tHcys) during the 2 last trimesters of normal pregnancy and related it to blood vitamin B12 and folate and to the excretion of the degraded intrinsic factor receptor (IFCR) in urine, in a follow-up study of 15 cases. A significant rise in tHcys was observed between the beginning of the second trimester and the third trimester with respective values (median) 6.1, 5.8 and 6.7 micromol/l (p = 0.038). The tHcys/albumin ratio also increased significantly, while no correlation was found between albumin and folate blood concentration. In contrast, a significant decrease in vitamin B12 was observed (279, 225 and 199 pmol/l, between the 4th and 6th, and the 6th and 9th month, respectively (p = 0.017-0.002)). A significant negative correlation was found between tHcys between the 4th and 9th month of pregnancy and the ratio of vitamin B12 between the 4th and 9th month of pregnancy (r = 0.55, p = 0.037). The urine excretion of IFCR was increased and was not related to vitamin B12 and tHcys. In conclusion, we have observed a rise in tHcys between the beginning of the second trimester and the third trimester of pregnancy which was related to the decreased blood level of vitamin B12. Subclinical deficiency of vitamin B12 should be further investigated in pregnant women who remain on inadequate diet.