Genetic Variation of Methylenetetrahydrofolate Reductase (MTHFR) and Thymidylate Synthase (TS) Genes Is Associated with Idiopathic Recurrent Implantation Failure

The Association Between Thymidylate Synthase Gene Polymorphisms and the Risk of Ischemic Stroke in Chinese Han Population

Family history of hypertension, smoking, diabetes and alcohol consumption and atherosclerotic plaque were identified as common risk factors in IS. We aimed at investigating the relationship between Thymidylate Synthase (TS) gene polymorphisms and ischemic stroke (IS).This case-control research selected and genotyped three single nucleotide polymorphisms (SNPs)of TS( rs699517, rs2790, and rs151264360) with Sanger sequencing in Chinese Han population. We also adopted logistic regression analysis in genetic models for calculating odds ratios and 95% confidence intervals. Genotype-Tissue Expression(GTEx) database analyzed the tissue-specific expression and TS polymorphisms. The ischemic stroke patients showed higher low-density lipoprotein cholesterol and total homocysteine (tHcy). It was found that patients with the TT genotype of rs699517 and GG genotype of rs2790 had larger degrees of tHcy than those with CC + CT genotypes and AA + AG genotypes, respectively. The genotype distribution of the three SNPs did not deviate from Hardy-Weinberg equilibrium (HWE). Haplotype analysis showed that T-G-del was the major haplotype in IS, and C-A-ins was the major haplotype in controls. GTEx database indicated that the rs699517 and rs2790 increased the expression of TS in healthy human and associated with TS expression level in a single tissue. In conclusion: This study has shown that TS rs699517 and rs2790 were significantly related to ischemic stroke patients.

A DNA Methylation Perspective on Infertility

Infertility affects a significant number of couples worldwide and its incidence is increasing. While assisted reproductive technologies (ART) have revolutionized the treatment landscape of infertility, a significant number of couples present with an idiopathic cause for their infertility, hindering effective management. Profiling the genome and transcriptome of infertile men and women has revealed abnormal gene expression. Epigenetic modifications, which comprise dynamic processes that can transduce environmental signals into gene expression changes, may explain these findings. Indeed, aberrant DNA methylation has been widely characterized as a cause of abnormal sperm and oocyte gene expression with potentially deleterious consequences on fertilization and pregnancy outcomes. This review aims to provide a concise overview of male and female infertility through the lens of DNA methylation alterations.

Genetic Variants in the Mitochondrial Thymidylate Biosynthesis Pathway Increase Colorectal Cancer Risk

We assess the contributions of genetic variants for the enzymes involved in capecitabine metabolism to colorectal cancer (CRC) development risk. In this case-control study, DNA samples were collected from 66 patients (King Abdulaziz University Hospital) and 65 controls (King Fahad General Hospital) between April and November 2022 to be used in PCR-RFLP. The chi-square (χ2) test at a significance level of p ˂ 0.05 was used to estimate genotype and allele frequencies. The Lys27Gln variant of cytidine deaminase (CDA) showed a risk ratio (RR) of 1.47 for heterozygous (AC) carriers, with genotype distributions for patients (χ2 = 1.97) and controls (χ2 = 14.7). Homozygous (AA) Ala70Thr carriers demonstrated a three-fold higher risk, with genotype distributions for patients (χ2 = 3.85) and controls (χ2 = 4.23). Genotype distributions of the 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T variant for patients were (χ2 = 22.43) and for controls were (χ2 = 0.07); for the MTHFR A1298C variant, they were (χ2 = 54.44) for patients and (χ2 = 4.58) for controls. Heterozygous (AC) carriers of the A1298C variant demonstrated highly significant protection against CRC development (RR = 0.2, p = 0.001), while a two-fold higher risk for CRC was estimated for homozygous genotype (CC) carriers. In conclusion, the heterozygous genotype of CDA Lys27Gln, the homozygous genotype of CDA Ala70Thr, and the homozygous genotype of MTHFR A1298C were associated with CRC development risk. The heterozygous genotype of MTHFR A1298C variant provided highly significant protection against CRC development. Further examinations using a larger population size are needed to reliably confirm our findings.

Variations in folate prescriptions for patients with the MTHFR genetic polymorphisms: A case series study

Background

Over 48.5 million couples are reported with infertility worldwide. Health policy recommends folic acid in women of childbearing age, particularly in preconception and pregnancy which results in women purchasing over-the-counter prenatal multivitamins containing folic acid through pharmacies and other retail outlets. Emerging studies are investigating whether other forms of supplemental folate are more suitable, particularly for those with methylenetetrahydrofolate reductase (MTHFR) polymorphisms. This case series aimed to document variations in forms and dosage of folate prescribed by Australian practitioners to patients with diagnosed infertility and MTHFR polymorphisms.

Methods

Australian practitioners were invited to complete a retrospective case report form for patients that presented with unexplained infertility. This case report form documented the form and dose of folate that practitioners were prescribing to their infertility patient with MTHFR polymorphisms, together with their fertility history.

Results

Six practitioners submitted case information for 12 patients with diagnosed infertility and MTHFR polymorphisms. All patients had been advised by their practitioner to remove folic acid in supplemental form and were prescribed 5-methyltetrahydrofolate (5-MTHF) or a combination of 5-MTHF and folinic acid, at higher doses than the Australian recommended dose (mean daily maximum prescribed dose: 2325μg). Eleven patients conceived within the treatment period (average treatment of one year) and ten were reported as having a live birth.

Conclusion

This case series has highlighted clinical practices that vary from the recommendations by Australian policy. Further research is required to verify the clinical importance of variations in folate prescriptions for women with MTHFR polymorphisms and how folate recommendations may need to change depending on these polymorphisms. This has direct relevance to those prescribing at the pharmacy and retail level, specifically pharmacists and pharmacy assistants.

Association of Polymorphisms in FSHR, INHA, ESR1, and BMP15 with Recurrent Implantation Failure

Recurrent implantation failure (RIF) refers to two or more unsuccessful in vitro fertilization embryo transfers in the same individual. Embryonic characteristics, immunological factors, and coagulation factors are known to be the causes of RIF. Genetic factors have also been reported to be involved in the occurrence of RIF, and some single nucleotide polymorphisms (SNPs) may contribute to RIF. We examined SNPs in FSHR, INHA, ESR1, and BMP15, which have been associated with primary ovarian failure. A cohort of 133 RIF patients and 317 healthy controls consisting of all Korean women was included. Genotyping was performed by Taq-Man genotyping assays to determine the frequency of the following polymorphisms: FSHR rs6165, INHA rs11893842 and rs35118453, ESR1 rs9340799 and rs2234693, and BMP15 rs17003221 and rs3810682. The differences in these SNPs were compared between the patient and control groups. Our results demonstrate a decreased prevalence of RIF in subjects with the FSHR rs6165 A>G polymorphism [AA vs. AG adjusted odds ratio (AOR) = 0.432; confidence interval (CI) = 0.206-0.908; p = 0.027, AA+AG vs. GG AOR = 0.434; CI = 0.213-0.885; p = 0.022]. Based on a genotype combination analysis, the GG/AA (FSHR rs6165/ESR1 rs9340799: OR = 0.250; CI = 0.072-0.874; p = 0.030) and GG-CC (FSHR rs6165/BMP15 rs3810682: OR = 0.466; CI = 0.220-0.987; p = 0.046) alleles were also associated with a decreased RIF risk. Additionally, the FSHR rs6165GG and BMP15 rs17003221TT+TC genotype combination was associated with a decreased RIF risk (OR = 0.430; CI = 0.210-0.877; p = 0.020) and increased FSH levels, as assessed by an analysis of variance. The FSHR rs6165 polymorphism and genotype combinations are significantly associated with RIF development in Korean women.

Histological endometrial dating: a reliable tool for personalized frozen-thawed embryo transfer in patients with repeated implantation failure in natural cycles

OBJECTIVE

To evaluate the clinical availability and stability of histological endometrial dating as a tool for personalized frozen-thawed embryo transfer (pFET) in patients with repeated implantation failure (RIF) in natural cycles.

METHODS

A total of 1245 RIF patients were recruited to the present study. All of the patients received an endometrial dating evaluation on day 7 post-ovulation (PO + 7) to guide their first pFET. The second and third pFETs were executed according to histological examination (again employing biopsy) or by reference to previous results. Subsequent pregnancy outcomes for all of the cycles were ultimately tracked.

RESULTS

The out-of-phase rate for RIF patients was 32.4% (404/1245) and the expected dating rate (the probability of the expected endometrial dating aligning with repeat biopsy) for endometrial dating reevaluation was as high as 94.3% (50/53). The clinical pregnancy rates of first, second, and third pFETs were 65.3%, 50.0%, and 44.4%, respectively; and the cumulative clinical pregnancy rate attained 74.9% after three transfers. Endometrial dating reevaluations met expectations with more than a 2-year duration in three cases and elicited favorable clinical outcomes.

CONCLUSION

We validated the relatively high stability of the histological endometrial dating platform-including the out-of-phase rate and the expected dating rate of reevaluation in patients with RIF-by expanding the sample size. The pFET, based on histological endometrial dating, was of acceptable clinical value and was worthy of promotion in patients with unexplained RIF.

Women Taking a Folic Acid Supplement in Countries with Mandatory Food Fortification Programs May Be Exceeding the Upper Tolerable Limit of Folic Acid: A Systematic Review

Background: In preconception and pregnancy, women are encouraged to take folic acid-based supplements over and above food intake. The upper tolerable limit of folic acid is 1000 mcg per day; however, this level was determined to avoid masking a vitamin B12 deficiency and not based on folic acid bioavailability and metabolism. This review’s aim is to assess the total all-source intake of folate in women of childbearing age and in pregnancy in high-income countries with folate food fortification programs. Methods: A systematic search was conducted in five databases to find studies published since 1998 that reported folate and folic acid intake in countries with a mandatory fortification policy. Results: Women of childbearing age do not receive sufficient folate intake from food sources alone even when consuming fortified food products; however, almost all women taking a folic acid-based supplement exceed the upper tolerable limit of folic acid intake. Conclusions: Folic acid supplement recommendations and the upper tolerable limit of 1000 mcg set by policy makers warrant careful review in light of potential adverse effects of exceeding the upper tolerable limit on folic acid absorption and metabolism, and subsequent impacts on women’s health during their childbearing years.

Epigenetics of Male Infertility: The Role of DNA Methylation

In recent years, a number of studies focused on the role of epigenetics, including DNA methylation, in spermatogenesis and male infertility. We aimed to provide an overview of the knowledge concerning the gene and genome methylation and its regulation during spermatogenesis, specifically in the context of male infertility etiopathogenesis. Overall, the findings support the hypothesis that sperm DNA methylation is associated with sperm alterations and infertility. Several genes have been found to be differentially methylated in relation to impaired spermatogenesis and/or reproductive dysfunction. Particularly, DNA methylation defects of MEST and H19 within imprinted genes and MTHFR within non-imprinted genes have been repeatedly linked with male infertility. A deep knowledge of sperm DNA methylation status in association with reduced reproductive potential could improve the development of novel diagnostic tools for this disease. Further studies are needed to better elucidate the mechanisms affecting methylation in sperm and their impact on male infertility.

Homocysteine, vitamin B status and MTHFR polymorphisms in Italian infertile women

OBJECTIVE

The purpose of this study was to evaluate the vitamin B status related to the homocysteine pathway and the prevalence of polymorphisms of the MTHFR gene in infertile women programming homologous or heterologous ART.

STUDY DESIGN

We investigated 393 consecutive Caucasian women, referred to the Internal Medicine Clinic at the Center for Assisted Reproductive Technology, in order to be framed for their vascular risk before starting homologous or heterologous (oocyte donation) procedures. Total homocysteine, Vitamin B12, folate and vitamin B6 were measured. The women were divided into quartiles of serum concentration of folate, vitamin B12 and vitamin B6. The C677T and A1298C polymorphisms of the MTHFR gene were genotyped by an electronic microchip technology.

RESULTS

Sixty-one women (15.5%) had hyperhomocysteinemia, 22.9% had reduced levels of vitamin B12, 4.1% had reduced levels of serum folate and 0.1% had a deficiency of vitamin B6. Women in the highest quartile of vitamin B12 and folates had lower homocysteine ​​levels than women in the first and second quartiles (p < 0.0001). The homozygosity for MTHFR C677T polymorphism was detected in 33.3% (131), and heterozygosity for MTHFR C677T polymorphism in 45.3% (178) of women. We observed a significant association between hyperhomocysteinemia and 677T allele, but not 1298C, of the MTHFR polymorphisms (p = 0.04).

CONCLUSIONS

We found inadequate vitamin B status related to the homocysteine ​​pathway in women planning Assisted Reproductive Technology. Moreover, interesting association was found regarding hyperhomocysteinemia in women carrying T allele of the C677T MTHFR polymorphism. A specific supplementation with 5-MTHF and adequate vitamin B12 concentrations before Assisted Reproductive Technology warrant serious consideration, in particular in women carrying T allele of the C677T MTHFR polymorphism.

Association between MTHFR polymorphisms (MTHFR C677T, MTHFR A1298C) and recurrent implantation failure: a systematic review and meta-analysis

OBJECTIVE

To investigate whether polymorphism of MTHFR C677T or MTHFR A1298C is associated with recurrent implantation failure (RIF).

STUDY DESIGN

This is a systematic review and meta-analysis. Pubmed, EMBASE, and CNKI (China national Knowledge Infrastructure) were searched for case-control studies that evaluated the associations between MTHFR polymorphisms (MTHFR C677T and MTHFR A1298C) and RIF. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were reported to evaluate the strength of association. Data were synthesized using the random-effect model.

RESULTS

Nine case-control studies consisted of 1812 women were included in the quantitative meta-analyses (754 were RIF patients, 1058 were control participants). The synthesized results showed that polymorphism of MTHFR C677T (allele model: OR 1.23, 95% CI 0.99-1.53; dominant model: OR 1.24, 95% CI 0.99-1.54; recessive model: OR 1.31, 95% CI 0.78-2.12; homozygotic model: OR 1.39, 95% CI 0.84-2.28; heterozygotic model: OR 1.14, 95% CI 0.90-1.45) or MTHFR A1298C (allele model: OR 1.11, 95% CI 0.78-1.59; dominant model: OR 0.91, 95% CI 0.65-1.26; recessive model: OR 2.04, 95% CI 0.90-4.64; homozygotic model: OR 1.86, 95% CI 0.79-4.38; heterozygotic model: OR 0.77, 95% CI 0.59-0.99) was not significantly associated with RIF.

CONCLUSIONS

Significant association of MTHFR polymorphisms (including MTHFR C677T and MTHFR A1298C) and RIF could not be confirmed.

Association of miR-27aA>G, miR-423C>a, miR-449bA>G, and miR-604A>G Polymorphisms with Risk of Recurrent Implantation Failure

Recurrent implantation failure (RIF) is defined when pregnancy failure occurs after two consecutive in vitro fertilization-embryo transfers to the endometrium using at least four high-quality embryos in women. MicroRNAs are well-known function modulators and are involved in many diseases. Recently, studies on microRNA and recurrent pregnancy loss (RPL) have been actively carried out; however, single nucleotide polymorphisms of miRNA in RPL are not well known. Therefore, we set the aim of this study to identify whether polymorphisms in miRNAs that miR-27aA>G, miR-423C>A, miR-449bA>G, and miR-604A>G are risk factors for idiopathic recurrent implantation failure (RIF) in Korean women. Genotyping was assessed with a polymerase chain reaction-restriction fragment length polymorphism assay. We examined polymorphisms in four miRNA genes: miR-27aA>G, miR-423C>A, miR-449bA>G, and miR-604A>G. We found that the miR-27aA>G, miR-449bA>G, and miR-604A>G polymorphisms were significantly associated with a risk of RIF. In addition, the miR-27aA>G and miR-449bA>G polymorphisms were associated with the frequency of implantation failures. Specifically, the miR-449bAG+GG genotype was associated with RIF prevalence (total RIF: adjusted odd ratio [AOR] = 1.584, 95% CI = 1.008-2.490, P = 0.046; IF ≥ 3 group: AOR = 1.747, 95% CI = 1.088-2.803, P = 0.021; IF ≥ 4: AOR = 1.932, 95% CI = 1.122-3.327, P = 0.018). Based on these results, the miR-449b A>G may be a predisposing factor to RIF susceptibility. However, the mechanism underlying the function of miR-449b A>G in RIF remains to be determined and further studies are needed to improve understanding of the roles of miR-449b A>G, using a larger and more heterogeneous cohort.

Genetic Causes of Female Infertility

Nowadays, women's family planning intentions are postponed, and it is common that only later will the conditions be created for the woman to have children. Fortunately, in most cases, pregnancy is possible in this case, taking into account the increased genetic risk. However, this later childbirth may become impossible or significantly more difficult if we can detect sterility and infertility, and its genetic cause is revealed. Any procedure that can help to reduce the "aging" of society, the reproduction rate, must be treated as an important public health issue. It would be particularly important in cases where genetic causes can be detected in the background of female sterility and infertility. Endocrine causes, infections, immunological causes, psychic factors, stress, and weight problems may be among the causes of female infertility in addition to genetic causes and genetic developmental disorders. Infertility can also be caused by iatrogenic factors, previous interventions, and surgery. In this chapter we will discuss the diseases in which genetic factors play a role.

Impact of RFC1, MTHFR, and MTHFD1 polymorphism on unexplained pregnancy loss (UPL): comparative analysis of maternal and fetal components using mother-abortus paired samples

In this study, we aimed to investigate associations between polymorphisms of folate metabolic pathway genes and unexplained pregnancy loss (UPL) using matched maternal-fetal samples. A total of 113 mother-abortus and 92 mother-newborn samples were collected. Among the 113 mother-abortus samples, 50 with chromosomal abnormality and 22 with maternal cell contamination were excluded. Samples were genotyped for RFC-1 80A>G, MTHFD1 1958 G>A, MTHFR 677C>T, and MTHFR 1298A>C polymorphisms using restriction fragment length polymorphism markers. The genotypes of RFC-1 80A>G, MTHFD1 1958 G>A, MTHFR 677C>T, and MTHFR 1298A>C were not associated with UPL in maternal samples. In the fetal samples, the frequency of heterozygous genotype (GA) of MTHFD11958 G>A was significantly higher than that that of the control (OR = 2.477, 95% CI = 1.128-5.446, p = 0.037). The AA-GA genotypes of MTHFD1 1958G>A and RFC-1 80A>G were significantly higher in mother-abortus samples (p = 0.016) than in the mother-newborn samples (p = 0.029). Frequencies of allelic combinations of MTHFR 677C>T/MTHFD11958G>A and RFC-1 80A>G/MTHFR677C>T/MTHFD1 1958G>A were significantly higher in maternal samples of the UPL group. In the fetal samples, no significant differences were detected between the UPL group and the control group. This study is the first to show associations between MTHFD1 1958G>A, RFC-1 80G>A, MTHFR 677C>T, and MTHFR 1298A>C polymorphisms and UPL and to compare the effects of maternal and fetal samples on UPL using mother-abortus matched samples of Korean origin.

Association Between miR-605A>G, miR-608G>C, miR-631I>D, miR-938C>T, and miR-1302-3C>T Polymorphisms and Risk of Recurrent Implantation Failure

Recurrent implantation failure (RIF) is diagnosed when pregnancy failure occurs after 2 consecutive in vitro fertilization-embryo transfers (IVF-ET) to the endometrium using at least 4 high-quality embryos. MicroRNAs (miRNAs) are a class of small noncoding RNA and reported to play an important role in cell proliferation as well as implantation process. Recently, it has been reported that miRNA can regulate RIF occurrence. So, we were to examine the association between the specific miRNA polymorphisms and RIF in Korean women. Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay to determine the frequency of the following polymorphisms: miR-605A>G, miR-608G>C, miR-631I>D, miR-938C>T, and miR-1302-3C>T. Our results demonstrate a decreased incidence of RIF in patients with the miR-1302-3C>T polymorphism (adjusted odds ratio [AOR], 0.234; 95% confidence interval [CI], 0.089-0.618; P = .003). Based on our allele combination analysis, the C-T ( miR-938/ miR-1302-3: OR = 0.259; 95% CI, 0.100-0.674; P = .003) allele was also associated with decreased RIF risk. From our interaction analysis with miR-1302-3, the miR-1302-3CC genotype (AOR = 43.332; 95% CI, 5.576-336.745) showed an association with RIF prevalence in participants with an activated partial thromboplastin time (aPTT) ≤22.6. We found that the miR-1302-3C>T polymorphism is significantly associated with RIF development in Korean women. Specifically, our study suggests that the T allele of miR-1302-3 may decrease the risk of RIF in Korean women.

The methylenetetrahydrofolate reductase c.c.677 C>T and c.c.1298 A>C polymorphisms in reproductive failures: Experience from an RSA and RIF study on a Polish population

Almost 1600 individuals from the Polish population were recruited to this study. Among them 319 were fertile couples, 289 were recurrent spontaneous abortion (RSA) couples, and 131 were in the group of recurrent implantation failure (RIF) following in vitro fertilization. The aim of this study was to evaluate the MTHFR c.c.677 C>T and c.c.1298 A>C polymorphisms’ association with RSA and RIF. We used PCR-RFLP with HinfI (677 C>T) and MboII (1298 A>C) digestion. We observed a protective effect of the female AC genotype (OR = 0.64, p = 0.01) and the C allele (AC+CC genotypes; OR = 0.65, p = 0.009) against RSA. Moreover, 1298 AA/677 CT women were more frequent in RSA (31.14%) and RIF (25.20%) groups in comparison to fertile women (22.88%), although this difference was significant only in the case of RSA (p = 0.022, OR = 1.52). Male combined genotype analysis revealed no association with reproductive failure of their partners. Nevertheless, the female/male combination AA/AC of the 1298 polymorphism was more frequent in RSA couples (p = 0.049, OR = 1.49). However, the significant results became insignificant after Bonferroni correction. In addition, analysis of haplotypes showed significantly higher frequency of the C/C haplotype (1298 C/677 C) in the female control group than in the female RSA group (p = 0.03, OR = 0.77). Moreover, the association between elevated homocysteine (Hcy) level in plasma of RSA and RIF women and MTHFR polymorphisms was investigated but did not reveal significant differences. In conclusion, for clinical practice, it is better to check the homocysteine level in plasma and, if the Hcy level is increased, to recommend patients to take folic acid supplements rather than undergo screening of MTHFR for 1298 A>C and 677 C>T polymorphisms.

The HLA-G 14-bp polymorphism and recurrent implantation failure: a meta-analysis

PURPOSE

The human leucocyte antigen-G (HLA-G) 14-bp insertion/deletion polymorphism was implicated in recurrent implantation failure (RIF), but individual published studies showed inconclusive results. Thus, a meta-analysis was performed to clarify the effect of HLA-G 14-bp polymorphism on RIF risk.

METHODS

A comprehensive search for relevant articles was conducted. The odds ratios (ORs) and 95% confidence intervals (CIs) for HLA-G 14-bp polymorphism and RIF were calculated.

RESULTS

A total of five studies were included. In studies conducted in RIF patients and controls who had at least one spontaneous pregnancy, meta-analysis revealed no statistically significant association between the HLA-G 14-bp polymorphism and RIF in allele contrast and all genetic models in the overall population, but significant association was found in the population of Caucasian origin under allele contrast (OR = 1.73, 95% CI, 1.20, 2.50) and genetic models of +14 bp/+14 bp vs. -14 bp/-14 bp (OR = 3.09, 95% CI, 1.43, 6.65). In studies conducted in RIF patients and controls who had successful pregnancy following IVF-ET, the meta-analysis showed that there was statistically significant association between the HLA-G 14 bp polymorphism and RIF in allele contrast (OR = 1.74, 95% CI, 1.13, 2.67) and genetic models of +14 bp/+14 bp vs. -14 bp/-14 bp (OR = 10.20, 95% CI, 2.47, 42.14) and dominant model (OR = 4.34, 95% CI, 1.72, 10.92). No publication bias was found in the present studies.

CONCLUSIONS

This meta-analysis suggested that the HLA-G 14-bp insertion allele may increase the risk of RIF in Caucasians. Further studies with large sample size of different ethnic populations are necessary.

Associative role of TYMS6bpdel polymorphism and resulting hyperhomocysteinemia in the pathogenesis of preterm delivery and associated complications: A study from Northeast India

Aberrations including genetic alterations in folate pathway are detrimental in multiple disease pathogenesis, including pregnancy. The present study is based on the screening of the associative role of TYMS 14946bp deletion(del) polymorphism and associated hyperhomocysteinemia in susceptibility to preterm delivery (PTD), which is strongly associated with neonatal mortality and morbidity.

METHODS

A total of 209 PTD cases {extremely preterm (n=22), very preterm (n=43) and moderately preterm (n=144)} and 194 term delivery cases were evaluated for TYMS 14946bp deletion and its association with preterm delivery, pregnancy outcome, baby birth weight and homocysteine estimation.

RESULTS

The results showed that the distribution of TYMS 14946bp del/del genotype significantly increased the risk of PTD [OR=2.801, p=0.002] and is associated with fetal death. The TYMS 6bp ins/del and 6bp del/del genotype was associated with low birth weight (LBW) compared to 6bp ins/ins genotype in both term and PTD groups, and in case of very (p=0.024) and moderately (p=0.045) sub-cohorts of PTD significantly. Elevated serum homocysteine levels were significantly associated with PTD (p<0.001) and fetal death (p=0.013); and was also found to significantly correlate with TYMS 14946bp del/del genotype in all the pregnancy cases (p=0.008). TYMS 6bp del/del genotype was associated with higher homocysteine levels compared to ins/ins (p=0.005) and ins/del (p=0.062) genotypes within the PTD group.

CONCLUSION

The study provides crucial information regarding the importance of TYMS6bpdel/del genotype and associated hyperhomocysteinemia in susceptibility to PTD, fetal death and LBW; and thus indicating their prognostic significance of TYMS 6bp del/del genotype in PTD which is of clinical importance.