A mutation (C677T) in the gene, MTHFR, is known to increase susceptibility to various multifactorial disorders. In order to assess this single nucleotide polymorphism (SNP) as risk factor for idiopathic male infertility, a case-control study was done on an Indian population. DNA from 151 cases of non-obstruction, idiopathic oligo-/azoospermia and 200 fertile males (controls) was polymerase chain reaction amplified using site-specific primers, and analysed for the mutation following HinfI-digestion. Our results show a significantly increased frequency of CT heterozygotes among infertile patients (p value <0.04). More importantly, while there were no T homozygotes in the control population, six of 151 infertile cases were T homozygous. Considering that T allele occurs in very low frequency in the control population, 677T is clearly a risk factor for infertility in the Indian population. We contend that the same could also be true for African and Southeast Asian populations where the frequency of 677T is very low. The lack of similar association in western populations could be because of the overall dietary enrichment of folates, which could nullify or minimize the effect of this polymorphism.

Down's syndrome (DS), a chromosomal disorder due to trisomy 21, results mostly from nondisjunction in maternal meiosis. The present case-control study examined the association of genetic polymorphisms with predisposition to nondisjunction. Two common polymorphisms (SNPs), C677T and A1298C, in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene involved in folate metabolism, are known to lower the activity of this enzyme. Three hundred and fourteen mothers (with DS children and controls), mostly from the eastern states of India, were genotyped for the two above-mentioned SNPs. Significant association with both of these SNPs were detected, more specifically, in the mothers of DS children homozygous for the polymorphic alleles 677 T and 1298 C. The relative risk of T (C677T) and C (A1298C) homozygosity in mothers for DS-affected pregnancy was 7 (OR 7.67, 95% CI 1.67-35.08, P=0.003) and 4 (OR 4.40, 95% CI 1.45-13.26, P=0.008), respectively. Moreover, all 677TT mothers studied were less than 31 years of age, whereas no correlation with maternal age was observed for A1298C genotypes. Interestingly, all of the young 677TT mothers had either a first-or secondborn child with DS. Thus, this study reports that young Indian mothers with TT genotypes are genetically predisposed to nondisjunction due to abnormal folate metabolism.

Background/Objectives: Unlike most Western populations, MTHFR 677T is a rare allele and a risk factor for a variety of disorders in India. What kind of nutritional (environmental) and/or genetic factors could contribute to the genetic risk is not known. To assess the incidence of hyperhomocysteinemia and its correlation with the polymorphism in homocysteine (Hcy)-pathway genes and associated cofactors in the native populations of eastern India. Subjects/Methods: Healthy population from four eastern states of India. Genotyping of SNPs, HPLC and chemiluminescencebased assay for homocysteine, vitamin B12 and folic acid.Results: Approximately 30% of the population has hyperhomocysteinemia (415 mmol/lit; hypHcy) with varying frequencies in the four states from where samples were collected (n ¼ 1426). Polymorphisms of MTR and CBS do not affect hypHcy. 677T and 1298C alleles of MTHFR and G80 RFC-1 show association with hypHcy. In contrast, RFC-1 80AA is protective even in presence of 677T MTHFR. Addition of each mutant allele has an additive effect on Hcy level. Vitamin B12 (cofactor in methionine synthesis) clearly modulates the genotypic effect on Hcy level. Although frequency of individuals with low folic acid is B11, 49% of the population is vitamin B12 deficient (o220 pg/lit) and has a significant negative correlation with Hcy. Individuals with optimum vitamin B12 and folic acid generally have low Hcy, even in risk genotypes. Conclusions: One of the plausible reasons for susceptibility of individuals with MTHFR C677T in the studied population to various disorders is the high frequency of hyperhomocysteinemia and vitamin B12 deficiency in the 'healthy population'. Apparently, supplementation of vitamin B 12 to this health-impoverished community may help lessen the risk of several multifactorial disorders.

The synthesis and secretion of proteins during development of the pancreas was analyzed using two-dimensional gel electrophoresis. The pattern of synthesis of the total proteins of the pancreas was found to change very little from 14 to 18 d gestation . In addition, the protein synthetic pattern of the embryonic pancreas was very similar to the protein patterns of several other embryonic tissues (gut, lung, and mesenchyme). Between 18 d gestation and the adult stage, the synthesis of the majority of protein species fades as the synthesis of the secretory (pro)enzymes becomes dominant . Thus, the terminal differentiation of the pancreas appears to involve the dominant expression of a limited set of genes (coding, in part, for the digestive [pro)enzymes) while the pattern of expression of the remaining domain remains relatively unchanged . Many of the secretory (pro)enzymes were identified and their synthesis during development was monitored . The synthesis of several secretory proteins was detected between 15 and 18 d gestation (e .g ., amylase and chymotrypsinogen), whereas the synthesis of others was not detected until after 18 d gestation (i .e ., trypsinogen, ribonuclease, proelastase, and lipase) . Between 18 d gestation and the adult stage, the synthesis of the digestive (pro)enzymes increases to >90% of pancreatic protein synthesis. The secretion of digestive (pro)enzymes was detected as early as 15 d gestation . The selective release of a second set of proteins was detected in the early embryo . These proteins are not detected in the adult pancreas or in zymogen granules but are also released by several other embryonic tissues. The function of this set of proteins is unknown .Pancreatic differentiation has been extensively studied at both morphological (18, 19) and biochemical levels (5,14,23,25). Normal development requires interaction between epithelial and mesenchymal tissues (8,25). Early investigations suggested that pancreatic differentiation is a multiphasic process (4, 21, 23) . In the rat, the formation of the pancreatic rudiment from the gut at -11 d gestation is coupled to the appearance of very low levels of exocrine proteins and insulin (the primary transition) . During the next 3-4 d, acinar structures form and the low levels of exocrine secretory proteins and insulin are maintained ("protodifferentiated state") (22, 23) . A second differentiative transition is detectable beginning at 14-15 d gestation when there is a rapid increase in rough endoplasmic reticulum, a 103-to 10'-fold increase in the accumulation of the specific exocrine enzymes and insulin, coupled with the appearance of zymogen granules in acinar cells and,8 granules in B cells (4,21,23) accumulate in a parallel fashion but slightly preceding the secretory proteins (10,11,20) .We have now used two-dimensional gel electrophoresis to monitor protein synthesis and secretion during development of the embryonic pancreas . This method allows analysis of both the pancreas-specific products (the secretory (projenzymes) and t...

In order to explore the significance of DNA methylation in proliferation and differentiation of germ cells in testis, 5-aza,2'-deoxyCytidine (5-azaCdR), a hypomethylating agent, was administered in vivo to neonatal mice having only spermatogonial (premeiotic) cells. End-labeling of the MspI, HpaII, and HhaI digested DNA revealed considerable loss of methylation following the treatment. Cellular and histological preparations of the testis showed complete inhibition of differentiation into spermatocytic stage. Analysis of protein synthesis in the treated and control testis by growing the cells in 35S-Methionine medium and resolving the lysate by SDS-PAGE revealed that the programme of expression of at least 5 polypeptides (35.0, 31.5, 27.0, 22.5, and 18.0 KD) was altered as a result of 5-azaCdR incorporation. It appears that DNA methylation plays a critical role in the differentiation of gonia into primary spermatocytes.