MTHFR: Addressing Genetic Counseling Dilemmas Using Evidence-Based Literature

Association of Methylenetetrahydrofolate Reductase rs1801133 Gene Polymorphism with Cancer Risk and Septin 9 Methylation in Patients with Colorectal Cancer

PURPOSE

Colorectal cancer (CRC) is one of the most common malignancies, with a high incidence and mortality worldwide. Methylated Septin 9 (mSEPT9) has been used clinically as an auxiliary tool for CRC screening. The aim of the present study was to investigate the association of the methylenetetrahydrofolate reductase (MTHFR) rs1801133 polymorphism with the risk of CRC and the methylation status of Septin 9 in CRC.

METHODS

Information of 540 patients with a confirmed diagnosis of CRC and with a physical examination were utilized to assess the association of the MTHFR rs1801133 polymorphism with CRC and the methylation of SEPT9. MTHFR rs1801133 polymorphism was genotyped using polymerase chain reaction (PCR). The commercial Septin 9 Gene Methylation(mSEPT9) Detection Kit was used for plasma SEPT9 methylation analysis.

RESULTS

Among 540 patients, 61.48% were men and the median age was 54.47 ± 13.14. 65.37% of all colorectal tumors developed in the rectum. 195 patients had negative mSEPT9 methylation, while 345 had positive results. 87 individuals with stage I, 90 with stage II, 287 with stage III, and 76 with stage IV colorectal cancer were included in the sample. The results demonstrated that the positivity rate and degree of methylation of mSEPT9 were remarkably higher in patients with more advanced TNM stages than in those with less advanced stages. The frequencies of the MTHFR rs1801133 CC genotype and allele C carriers in patients with CRC were significantly higher than those in healthy individuals (P = 0.006 and P = 0.001, respectively). The positivity rate of the mSEPT9 assay was significantly higher among the MTHFR rs1801133 TT genotype and allele T carriers than among the CC and allele C carriers respectively. The MTHFR rs1801133 TT genotype and allele T carriers were positively associated with the methylation of SEPT9 (OR = 3.320, 95% CI 1.485-7.424, P = 0.003 and OR = 1.783, 95% CI 1.056-3.010, P = 0.030, respectively).

CONCLUSION

In conclusion, individuals harboring the MTHFR rs1801133 CC genotype had a higher risk of CRC and the MTHFR rs1801133 TT carriers were more susceptible to Septin 9 gene methylation.

Methylenetetrahydrofolate reductase polymorphic variants C677T and A1298C in rectal cancer in Slavic population: significance for cancer risk and response to chemoradiotherapy

Background: Methylenetetrahydrofolate reductase (MTHFR) single nucleotide polymorphisms (SNPs) have been suggested as risk, prognostic, and predictive factors for colorectal cancer in various populations, but have not been validated so far. The aim of this study was to examine the association of MTHFR C677T (rs1801133) and A1298C (rs1801131) single nucleotide polymorphisms with the risk of rectal cancer as well as the response to neoadjuvant chemoradiotherapy (nCRT) based on 5-Fluorouracil (5-FU)/leucovorin (LV) in the locally advanced setting. Patients and methods: This case-control study included 119 healthy controls and 97 patients with locally advanced rectal cancer (LARC). For MTHFR genotyping, restriction fragment length polymorphism analysis (PCR-RFLP) was employed. Results: In silico analysis highlighted that SNPs C677T and A1298T correlate with MTHFR gene expression, and that gene expression profile correlates with cancer risk and stage. Using dominant and recessive models, it was found that the MTHFR 677CC vs. 677CT+677TT have increased risk of cancer development (odds ratio (OR): 2.27; 95% confidence interval (CI): 1.30-3.95, p = 0.002) as well as 677CC+677CT compared to 677TT (OR: 4.18, 95% CI: 1.16-14.99, p = 0.014). MTHFR 1298AA also shown increased risk for cancer development compared to 1298AC+1298CC (OR:2.0, 95% CI: 1.20-3.59, p = 0.035) Statistical analysis of combined genotypes highlighted the protective role of CT/AC combined genotype (OR: 3.15 95% CI: 1.576-6.279, p = 0.002) while the CC/AA genotype showed an increased risk for rectal cancer development (OR: 2.499, 95% CI: 1.246-5.081, p = 0.016) The carriers of the 677C/1298A haplotype had the highest risk for developing rectal cancer (OR: 1.74; 95% CI: 1.198-2.530, p = 0.002) while the 677T/1298C haplotype seems to provide a protective effect. (OR: 0.44; 95%CI 0.248-0.795, p = 0.003). No significant association with response to chemoradiotherapy was found. Conclusion: Our data point to MTHFR 667C allele and 1298A alleles as low-penetrance risk factors for rectal cancer in our population. To the best of our knowledge, this is the first study of this type performed on the Slavic population in the Western Balkan, as various population-based factors might also be significant our findings can be used for future meta-analyses and the construction of genetic cancer risk prediction panels.

MTHFR Gene C677T Polymorphism (rs1801133) and Susceptibility to Colorectal Polyps in an Azerbaijani Population

BACKGROUND

Understanding the relationships between the methylenetetrahydrofolate reductase (MTHFR) gene polymorphism, colorectal polyps, and CRC risk can aid in advancing personalized medicine approaches in CRC prevention. The aim of the current study is to identify the association of C677T polymorphism of the MTHFR gene with the risk of colorectal polyps in the Azerbaijani population.

METHODS

This study included 125 patients with colon polyps and 155 healthy individuals as a control group. DNA was extracted from venous blood samples obtained from patients and healthy individuals, and the results were analyzed through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and agarose gel electrophoresis.

RESULTS

Wild-type, heterozygote, and homozygous mutant were revealed within 69 (55.2%), 49 (39.2%), and 7 (5.6%) patients and within 100 (64.5%), 45 (29%), and 10 (6.5%) healthy controls, respectively. However, no significant statistical associations were observed between CT and TT genotypes, dominant (CC vs. CT + TT) and recessive (CC + CT vs. TT) models, and the mutant T allele and disease risk. There were also no significant differences between patients and controls regarding age, sex, smoking and alcohol use.

CONCLUSION

Our research did not reveal any significant association between the MTHFR C677T polymorphism and susceptibility to colorectal polyps in the Azerbaijan population.

Recovery from (treatment-resistant) depression after lifestyle changes and micronutrient precision supplementation: a preliminary field study in patients

BACKGROUND AND PURPOSE

The incidence of depression is increasing, despite continued advances in psychological and pharmacological interventions. New treatment approaches are urgently needed. Here we assess the effects on depression of individualized micronutrient supplementation, in concert with a standard set of lifestyle changes.

METHODS

We conducted a small field-study with 17 participants in Austria. Patients with depression (n = 11) and healthy volunteers (n = 6) underwent laboratory serum analysis and filled out the DASS-21 and a questionnaire about their medical history and condition. The list of parameters to be tested in the serum analysis was derived from an expert heuristic compilation of factors known to influence depression, narrowed down to a workable list to be tested in this initial study. On the basis of the results, the participants (n = 17) received individualized recommendations for micronutrient supplementation, in collaboration with their treating physician. Participants followed the individual supplementation regime for two months, along with a standard set of lifestyle changes. After two months the laboratory serum analyses, the DASS-21, and the questionnaire were repeated.

RESULTS

All patients with micronutrient deficiencies were in the patient group; none of the healthy volunteers showed any micronutrient deficiencies. After two months of precision supplementation and lifestyle changes, all but one patient had recovered from their depression or had considerably improved. The one patient who didn't recover was the only one with a known trigger of their depression (trauma). Of 11 patients with depression, the trigger was unknown for the other ten.

CONCLUSIONS

These results have promising implications for further research, treatment, drug development, and public health. We propose that systematic screening of patients with symptoms of depression be developed for future research, medical care, and practice. Psychiatry and psychotherapy may see improved results once they no longer have to push against the underlying constraints of existing micronutrient deficiencies.

Contribution of Genetic Test to Early Diagnosis of Methylenetetrahydrofolate Reductase (MTHFR) Deficiency: The Experience of a Reference Center in Southern Italy

BACKGROUND

the deficiency of 5,10-Methylenetetrahydrofolate reductase (MTHFR) constitutes a rare and severe metabolic disease and is included in most expanded newborn screening (NBS) programs worldwide. Patients with severe MTHFR deficiency develop neurological disorders and premature vascular disease. Timely diagnosis through NBS allows early treatment, resulting in improved outcomes.

METHODS

we report the diagnostic yield of genetic testing for MTHFR deficiency diagnosis, in a reference Centre of Southern Italy between 2017 and 2022. MTHFR deficiency was suspected in four newborns showing hypomethioninemia and hyperhomocysteinemia; otherwise, one patient born in pre-screening era showed clinical symptoms and laboratory signs that prompted to perform genetic testing for MTHFR deficiency.

RESULTS

molecular analysis of the MTHFR gene revealed a genotype compatible with MTHFR deficiency in two NBS-positive newborns and in the symptomatic patient. This allowed for promptly beginning the adequate metabolic therapy.

CONCLUSIONS

our results strongly support the need for genetic testing to quickly support the definitive diagnosis of MTHFR deficiency and start therapy. Furthermore, our study extends knowledge of the molecular epidemiology of MTHFR deficiency by identifying a novel mutation in the MTHFR gene.

Maternal Thrombophilic and Hypofibrinolytic Genetic Variants in Idiopathic Recurrent Pregnancy Loss: a Continuing Mystery

Despite the fact that multiple recurrent pregnancy loss (RPL) etiologies have been identified, 50-70% of RPL cases remain enigmatic, and idiopathic RPL is still a serious medical challenge. A plethora of studies have investigated the correlation of RPL with variations in coagulation and/or fibrinolytic factors-encoding genes. Notwithstanding, evidence for a link between these variations and RPL remains discordant. We aimed to explore the association of thrombophilic and hypofibrinolytic gene variations with RPL development. Two hundred Saudi women were recruited in this study, comprising 150 women experiencing RPL and 50 healthy women. Thirteen genetic variants, including FV G1691A, FV A4070G, F2 G20210A, F13A1 G103T, FGB - 455G > A, PAI-1 - 675 4G/5G, ITGB3 T1565C, MTHFR C677T, MTHFR A1298C, ACE I/D, APOB G10708A, APOE T388C, and APOE C526T were genotyped using ViennaLab StripAssay. Women experiencing RPL harbor significantly higher frequencies of the F13A1 103 T, FGB - 455A, and ITGB3 1565C alleles than control women (p < 0.001). No differences in the prevalence of other investigated variants were identified between control women and those with RPL. No considerable link of F5 1691G > A/4070A > G, MTHFR 677C > T/1298A > C, and APOE 388 T > C/526C > T haplotypes with RPL risk was demonstrated. F13A1 G103T, FGB - 455G > A, and ITGB3 T1565C variants are connected to a higher likelihood of developing RPL and, hence, may have the potential to identify those women at risk of RPL, thereby, improving RPL susceptibility prediction. Incorporating molecular testing of thrombophilic and hypofibrinolytic genetic variants into routine workup could confer a promising approach for refined RPL risk assessment.

Epigenetic Regulation by microRNAs in Hyperhomocysteinemia-Accelerated Atherosclerosis

Increased serum levels of homocysteine (Hcy) is a risk factor for cardiovascular disease and is specifically linked to various diseases of the vasculature such as atherosclerosis. However, the precise mechanisms by which Hcy contributes to this condition remain elusive. During the development of atherosclerosis, epigenetic modifications influence gene expression. As such, epigenetic modifications are an adaptive response to endogenous and exogenous factors that lead to altered gene expression by methylation and acetylation reactions of different substrates and the action of noncoding RNA including microRNAs (miRNAs). Epigenetic remodeling modulates cell biology in both physiological and physiopathological conditions. DNA and histone modification have been identified to have a crucial role in the progression of atherosclerosis. However, the potential role of miRNAs in hyperHcy (HHcy)-related atherosclerosis disease remains poorly explored and might be essential as well. There is no review available yet summarizing the contribution of miRNAs to hyperhomocystein-mediated atherogenicity or their potential as therapeutic targets even though their important role has been described in numerous studies. Specifically, downregulation of miR-143 or miR-125b has been shown to regulate VSCMs proliferation in vitro. In preclinical studies, downregulation of miR-92 or miR195-3p has been shown to increase the accumulation of cholesterol in foam cells and increase macrophage inflammation and atherosclerotic plaque formation, respectively. Another preclinical study found that there is a reciprocal regulation between miR-148a/152 and DNMT1 in Hcy-accelerated atherosclerosis. Interestingly, a couple of studies have shown that miR-143 or miR-217 may be used as potential biomarkers in patients with HHcy that may develop atherosclerosis. Moreover, the current review will also update current knowledge on miRNA-based therapies, their challenges, and approaches to deal with Hcy-induced atherosclerosis.

Association Study between Polymorphisms in DNA Methylation-Related Genes and Testicular Germ Cell Tumor Risk

BACKGROUND

Testicular germ cell tumors (TGCT), histologically classified as seminomas and nonseminomas, are believed to arise from primordial gonocytes, with the maturation process blocked when they are subjected to DNA methylation reprogramming. SNPs in DNA methylation machinery and folate-dependent one-carbon metabolism genes have been postulated to influence the proper establishment of DNA methylation.

METHODS

In this pathway-focused investigation, we evaluated the association between 273 selected tag SNPs from 28 DNA methylation-related genes and TGCT risk. We carried out association analysis at individual SNP and gene-based level using summary statistics from the Genome Wide Association Study meta-analysis recently conducted by the international Testicular Cancer Consortium on 10,156 TGCT cases and 179,683 controls.

RESULTS

In individual SNP analyses, seven SNPs, four mapping within MTHFR, were associated with TGCT risk after correction for multiple testing (q ≤ 0.05). Queries of public databases showed that three of these SNPs were associated with MTHFR changes in enzymatic activity (rs1801133) or expression level in testis tissue (rs12121543, rs1476413). Gene-based analyses revealed MTHFR (q = 8.4 × 10-4), methyl-CpG-binding protein 2 (MECP2; q = 2 × 10-3), and ZBTB4 (q = 0.03) as the top TGCT-associated genes. Stratifying by tumor histology, four MTHFR SNPs were associated with seminoma. In gene-based analysis MTHFR was associated with risk of seminoma (q = 2.8 × 10-4), but not with nonseminomatous tumors (q = 0.22).

CONCLUSIONS

Genetic variants within MTHFR, potentially having an impact on the DNA methylation pattern, are associated with TGCT risk.

IMPACT

This finding suggests that TGCT pathogenesis could be associated with the folate cycle status, and this relation could be partly due to hereditary factors.

Possible effect of genetic background in thrombophilia genes on clinical severity of patients with coronavirus disease-2019: A prospective cohort study

Background and objective: Thrombotic and microangiopathic effects have been reported in Coronavirus Disease-2019 (COVID-19) patients. In the present study, we aimed to examine the relationship between hereditary thrombophilia factors and the clinical picture severity of COVID-19 patients. Methods: Ninety COVID-19 patients were included and grouped according to the severity to three groups: severe/critical (n=30), mild/moderate (n=30) and asymptomatic (n=30). Hereditary thrombophilia genetic markers [prothrombin (FII) G20210A, factor V Leiden (FVL) G1691A, factor XIII (FXIII) V34L, methylene tetrahydrofolate reductase (MTHFR) A1298C and C677T, and plasminogen activator inhibitor-1 (PAI-1) 4G & 5G] were genotyped for all patients. Results: Seventeen (18.9%) patients had the polymorphism 4G/4G PAI-1 and 48 (53.3%) had 4G/5G. In addition, the heterozygous GA FVL, MTHRF677CT, and MTHRF1298AC polymorphisms were detected in 11 (12.2%), 26 (28.9%), and 38 (42.2%) patients, respectively. The rate of severe/critical patients with PAI 4G/5G gene polymorphism was higher than the asymptomatic+moderate/mild patients, and the rate of severe/critically ill patients with PAI 4G/4G polymorphism was found to be lower than the asymptomatic+moderate/mild patients. No difference was evidenced between the distribution of deceased and survivors of the genotype groups. Conclusions: In the present study, we found that heterozygous 4G/5G PAI-1 polymorphism is associated with critical or severe COVID-19 picture, and that FVL, MTHFR, FXIII, and prothrombin polymorphisms were not directly related to COVID-19 severity.

Associations of Two Common Polymorphisms in MTHFR Gene with Blood Lipids and Therapeutic Efficacy of Simvastatin

BACKGROUND AND PURPOSE

Cardio-cerebrovascular disease is an important public health challenge worldwide, and its complex etiology has not been elucidated fully. The study was to investigate the relationship between two common polymorphisms C677T and A1298C in the methylenetetrahydrofolate reductase (MTHFR) gene, baseline lipids and the lipid-lowering efficacy of simvastatin in a Chinese hyperlipidemic population.

METHODS

All participants were recruited from Anhui, China. By the extreme sampling method, we selected subjects with low response (n=108) and high response (n=106) based on their adjusted lipid-lowering response to simvastatin administrated for 8 consecutive weeks. Both MTHFR C677T and A1298C loci were genotyped by MALDI-TOF MS platform. Serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels were measured at baseline and after 8 weeks of oral 20 mg/d tablet of simvastatin.

RESULTS

Patients with the 677TT genotype had significantly higher baseline TC, HDL-C, and change in HDL-C (ΔHDL-C) levels after treatment than those with 677CC+CT genotypes (β = 0.207, P = 0.045; β = 0.182, P = 0.026; and β = 0.16, P = 0.002, respectively). Patients with 1298AC+CC genotypes had significantly higher baseline LDL-C and change in LDL-C (ΔLDL-C) levels (β = 0.276, P =0.043; β = 0.359, P = 0.025, respectively) than those with 1298AA genotype. We found statistical interactions between the two SNPs in association with baseline HDL-C (P for interaction = 0.034), TC (P for interaction = 0.069), and TG (P for interaction = 0.034). Baseline TC (P = 0.027) and HDL-C (P = 0.046) and change in HDL-C (P = 0.019) were different among those with the MTHFR A-T haplotype compared with A-C.

CONCLUSIONS

Our major findings suggest that both MTHFR C677T and A1298C polymorphisms could be important genetic determinants of lipid traits and drug efficacy of simvastatin. This will contribute to a better understanding of strategies for personalized medication in Chinese patients with dyslipidemia.

Personalized Nutrition in the Management of Female Infertility: New Insights on Chronic Low-Grade Inflammation

Increasing evidence on the significance of nutrition in reproduction is emerging from both animal and human studies, suggesting a mutual association between nutrition and female fertility. Different “fertile” dietary patterns have been studied; however, in humans, conflicting results or weak correlations are often reported, probably because of the individual variations in genome, proteome, metabolome, and microbiome and the extent of exposure to different environmental conditions. In this scenario, “precision nutrition”, namely personalized dietary patterns based on deep phenotyping and on metabolomics, microbiome, and nutrigenetics of each case, might be more efficient for infertile patients than applying a generic nutritional approach. In this review, we report on new insights into the nutritional management of infertile patients, discussing the main nutrigenetic, nutrigenomic, and microbiomic aspects that should be investigated to achieve effective personalized nutritional interventions. Specifically, we will focus on the management of low-grade chronic inflammation, which is associated with several infertility-related diseases.

An Update in Our Understanding of the Relationships Between Gene Polymorphisms and Chemotherapy-Induced Nausea and Vomiting

The occurrence and severity of chemotherapy-induced nausea and vomiting (CINV) are influenced by many factors; this includes therapeutic factors, such as the dose, administration mode, and chemotherapeutic agent emetogenicity, as well as patient-related risk factors, such as the gender, age, alcohol consumption history, and anxiety level. However, these factors cannot fully explain the individual CINV differences. In recent years, the correlation between gene polymorphism and CINV has been a hot research topic; the present paper reviews current research on CINV-related gene polymorphisms, and the results indicate that the use of gene polymorphism for the optimization of CINV efficacy is of important clinical significance.

Oral manifestations associated with inherited hyperhomocysteinemia: A first case description

Hyperhomocysteinemia is a rare disease caused by nutritional deficiencies or genetic impairment of cysteine metabolism. To date, no oral manifestations of hyperhomocysteinemia have been described in humans. Therefore, to our knowledge, the present case report is the first description of a hyperhomocysteinemic patient showing oral tissue alterations leading to both early tooth loss and failed implant osseointegration. The patient presented with a methylenetetrahydrofolate reductase gene mutation (677T polymorphism) leading to mild hyperhomocysteinemia. The radiologic analysis showed hyperdense lesions scattered in the maxillae. The histologic observations indicated alterations in both collagen and elastic networks in the gingiva and dermis. Interestingly, the presence of ectopic mineralized inclusions was noted in both periodontal ligament and gingiva. Strong osteoclastic activity was associated with abnormal calcification of trabecular spaces. Uneven oral tissue remodeling due to high tissue levels of homocysteine could explain the pathologic manifestations observed in this case.

Influence of FPGS, ABCC4, SLC29A1, and MTHFR genes on the pharmacogenomics of fluoropyrimidines in patients with gastrointestinal cancer from the Brazilian Amazon

PURPOSE

Fluoropyrimidines are one of the most used drug class to treat cancer patients, although they show high levels of associated toxicity. This study analyzed 33 polymorphisms in 17 pharmacogenes involved with the pharmacogenomics of fluoropyrimidines, in gastrointestinal cancer patients undergoing fluoropyrimidine-based treatment in the Brazilian Amazon.

METHODS

The study population was composed of 216 patients, 92 of whom have an anatomopathological diagnosis of gastric cancer and 124 of colorectal cancer. The single nucleotide polymorphisms (SNP) were genotyped by allelic discrimination using the TaqMan OpenArray Genotyping technology, with a panel of 32 customized assays, run in a QuantStudio ™ 12K Flex Real-Time PCR System (Applied Biosystems, Life Technologies, Carlsbad USA). Ancestry analysis was performed using 61 autosomal ancestry informative markers (AIMs).

RESULTS

The study population show mean values of 48.1% European, 31.1% Amerindian, and 20.8% African ancestries. A significant risk association for general and severe toxicity was found in the rs4451422 of FPGS (p = 0.001; OR 3.40; CI 95% 1.65-7.00 and p = 0.006; OR 4.63; CI 95% 1.56-13.72, respectively) and the rs9524885 of ABCC4 (p = 0.023; OR 2.74; CI 95% 1.14-6.65 and p = 0.024; OR 5.36; IC 95% 1.24-23.11, respectively) genes. The rs760370 in the SLC29A1 gene (p = 0.009; OR 6.71; CI 95% 1.16-8.21) and the rs1801133 in the MTHFR toxicity (p = 0.023; OR 3.09; CI 95% 1.16-8.21) gene also demonstrated to be significant, although only for severe toxicity. The results found in this study did not have statistics analysis correction.

CONCLUSION

Four polymorphisms of the ABCC4, FPGS, SLC29A1, and MTHFR genes are likely to be potential predictive biomarkers for precision medicine in fluoropyrimidine-based treatments in the population of the Brazilian Amazon, which is constituted by a unique genetic background.

MTHFR C677T and A1298C Polymorphisms in Breast Cancer, Gliomas and Gastric Cancer: A Review

Folate (vitamin B9) is found in some water-soluble foods or as a synthetic form of folic acid and is involved in many essential biochemical processes. Dietary folate is converted into tetrahydrofolate, a vital methyl donor for most methylation reactions, including DNA methylation. 5,10-methylene tetrahydrofolate reductase (MTHFR) is a critical enzyme in the folate metabolism pathway that converts 5,10-methylenetetrahydrofolate into 5-methyltetrahydrofolate, which produces a methyl donor for the remethylation of homocysteine to methionine. MTHFR polymorphisms result in reduced enzyme activity and altered levels of DNA methylation and synthesis. MTHFR polymorphisms have been linked to increased risks of several pathologies, including cancer. Breast cancer, gliomas and gastric cancer are highly heterogeneous and aggressive diseases associated with high mortality rates. The impact of MTHFR polymorphisms on these tumors remains controversial in the literature. This review discusses the relationship between the MTHFR C677T and A1298C polymorphisms and the increased risk of breast cancer, gliomas, and gastric cancer. Additionally, we highlight the relevance of ethnic and dietary aspects of population-based studies and histological stratification of highly heterogeneous tumors. Finally, this review discusses these aspects as potential factors responsible for the controversial literature concerning MTHFR polymorphisms.

The expectations and realities of nutrigenomic testing in australia: A qualitative study

BACKGROUND

Consumer genomic testing for nutrition and wellness, (nutritional genomics), is becoming increasingly popular. Concurrently, health-care practitioners (HPs) working in private practice (including doctors interested in integrative medicine, private genetic counsellors, pharmacists, dieticians, naturopaths and nutritionists) are involved as test facilitators or interpreters.

OBJECTIVE

To explore Australian consumers' and HPs' experiences with nutrigenomic testing.

METHOD

Semi-structured in-depth interviews were conducted using predominantly purposive sampling. The two data sets were analysed individually, then combined, using a constant comparative, thematic approach.

RESULTS

Overall, 45 interviews were conducted with consumers (n = 18) and HPs (n = 27). Many of the consumer interviewees experienced chronic ill-health. Nutrigenomic testing was perceived as empowering and a source of hope for answers. While most made changes to their diet/supplements post-test, self-reported health improvements were small. A positive relationship with their HP appeared to minimize disappointment. HPs' adoption and views of nutrigenomic testing varied. Those enthusiastic about testing saw the possibilities it could offer. However, many felt nutrigenomic testing was not the only 'tool' to utilize when offering health care.

DISCUSSION

This research highlights the important role HPs play in consumers' experiences of nutrigenomics. The varied practice suggests relevant HPs require upskilling in this area to at least support their patients/clients, even if nutrigenomic testing is not part of their practice.

PATIENT OR PUBLIC CONTRIBUTION

Advisory group included patient/public group representatives who informed study design; focus group participants gave feedback on the survey from which consumer interviewees were sourced. This informed the HP data set design. Interviewees from HP data set assisted with snowball sampling.

Livedoid vasculopathy and its association with genetic variants: A systematic review

Livedoid vasculopathy (LV) is considered a disease of hypercoagulability. Association of LV with genetic variants is poorly characterised and large‐scale genetic association studies have not been performed. The aim of the study was to systematically review variants in LV patients and to analyse the available clinical data. A systematic search of the literature in PubMed and Embase databases was performed to identify articles investigating genetic variation in LV patients. Thirty studies or case reports were identified that reported 265 LV patients tested for at least one out of six genetic variations. Among them, PAI‐1 ‐675 4G/5G was the most common, accounting for 85.26% (81/95). Heterozygous 4G/5G was the major genotype. PAI‐1 A844G, MTHFR C677T, and MTHFR A1298C were the second, third, and fourth most common variants in LV patients. Prothrombin G20210A and Factor V G1691A were mainly present in LV patients from Europe, North America, and South America. This review highlights the associations between LV and genetic variants. The distribution of variants may be geographically or ethnicity dependent; however, large sample case‐control studies are needed to clarify associations.

Venous thrombosis after nitrous oxide abuse, a case report

Nitrous oxide is a commonly abused inhalant by adolescents and young adults. There is limited data describing the adverse effects of nitrous oxide abuse, known colloquially as "whippets". We present a 21-year-old female with no medical history who presented to the emergency department for confusion, hallucinations, weakness, and falls. She was accompanied by her roommates, who endorsed significant nitrous oxide abuse. Imaging revealed a large cerebral sinus venous thrombus with extension into the transverse sinus, sigmoid sinus and internal jugular vein. She had no prior history of venous or arterial thrombosis. Hypercoagulability workup demonstrated an elevated homocysteine level, elevated methylmalonic acid level, and normal cobalamin and folate levels. Additionally, she was found to be 11 weeks pregnant, with no prior spontaneous abortions. Genetic testing was significant for methylenetetrahydrofolate reductase polymorphisms. She was managed with enoxaparin, cobalamin and folate supplementation. Homocysteine and methylmalonic acid levels normalized after cessation of nitrous oxide use, with no recurrence of venous thrombosis. This case represents the first reported patient with a venous thrombus associated with nitrous oxide abuse.

Association Between MTHFR C677T Polymorphism and Susceptibility to Autism Spectrum Disorders: A Meta-Analysis in Chinese Han Population

Prior studies have examined the influence of MTHFR C677T on autism susceptibility, however, there are no consensus conclusions and specific analyses of a Chinese population. This meta-analysis included a false-positive report probability (FPRP) test to comprehensively evaluate the association of MTHFR C677T polymorphism with autism susceptibility among a Chinese Han population. A large-scale literature retrieval was conducted using various databases including PubMed, Embase, Wan Fang, and the Chinese National Knowledge Infrastructure (CNKI) up to July 31, 2020, with a total of 2,258 cases and 2,073 controls included. The strength of correlation was assessed by odds ratios (ORs) and 95% confidence intervals (95% CIs). MTHFR C677T showed a significant correlation with increased ASD susceptibility under all genetic models (T vs. C, OR = 1.89, 95% CI 1.28 to 2.79; TT vs. CC: OR = 2.44, 95% CI 1.43 to 4.15; CT vs. CC, OR = 1.73; 95% CI 1.19 to 2.51; CT + TT vs. CC: OR = 2.03, 95% CI 1.31 to 3.15; TT vs. CT + CC, OR = 1.95, 95% CI 1.21 to 3.13). Stratification analysis by region also revealed a consistent association in the Northern Han subgroup, but not in the Southern Han subgroup. Pooled minor allele frequency (MAF) of 30 studies were 45% in Northern Han and 39% in Southern Han. To avoid a possible "false positive report," we further investigated the significant associations observed in the present meta-analysis using the FPRP test, which consolidated the results. In conclusion, MTHFR C677T polymorphism is associated with the increased risk of autism in China, especially in Northern Han. For those mothers and children who are generally susceptible to autism, prenatal folate and vitamin B12 may reduce the risk that children suffer from autism, especially in Northern Han populations. In the future, more well-designed studies with a larger sample size are expected.

Pharmacodynamic Gene Testing in Prader-Willi Syndrome

Prader-Willi syndrome (PWS) is a rare genetic disorder with a complex neurobehavioral phenotype associated with considerable psychiatric co-morbidity. This clinical case series, for the first time, describes the distribution and frequency of polymorphisms of pharmacodynamic genes (serotonin transporter, serotonin 2A and 2C receptors, catechol-o-methyltransferase, adrenergic receptor 2A, methylene tetrahydrofolate reductase, and human leucocytic antigens) across the two major molecular classes of PWS in a cohort of 33 referred patients who met medical criteria for testing. When results were pooled across PWS genetic subtypes, genotypic and allelic frequencies did not differ from normative population data. However, when the genetic subtype of PWS was examined, there were differences observed across all genes tested that may affect response to psychotropic medication. Due to small sample size, no statistical significance was found, but results suggest that pharmacodynamic gene testing should be considered before initiating pharmacotherapy in PWS. Larger scale studies are warranted.

The 1316T>C missenses mutation in MTHFR contributes to MTHFR deficiency by targeting MTHFR to proteasome degradation

5,10-methylenetetrahydrofolate reductase (MTHFR) deficiency is a rare hereditary disease characterized by defects in folate and homocysteine metabolism. Individuals with inherited MTHFR gene mutations have a higher tendency to develop neurodegeneration disease as Alzheimer’ disease and atherosclerosis. MTHFR is a rate-limiting enzyme catalyzing folate production, various SNPs/mutations in the MTHFR gene have been correlated to MTHFR deficiency. However, the molecular mechanisms underpinning the pathogenic effects of these SNPs/mutations have not been clearly understood. In the present study, we reported a severe MTHFR deficiency patient with late-onset motor dysfunction and sequenced MTHFR gene exons of the family. The patient carries an MD-associating SNP (rs748289202) in one MTHFR allele and the rs545086633 SNP with unknown disease relevance in the other. The rs545086633 SNP (p.Leu439Pro) results in an L439P substitution in MTHFR protein, and drastically decreases mutant protein expression by promoting proteasomal degradation. L⁴³⁹ in MTHFR is highly conserved in vertebrates. Our study demonstrated that p.Leu439Pro in MTHFR is the first mutation causing significant intracellular defects of MTHFR, and rs545086633 should be examined for the in-depth diagnosis and treatment of MD.

MTHFR rs1801133 Polymorphism Is Associated With Liver Fibrosis Progression in Chronic Hepatitis C: A Retrospective Study

Background: The MTHFR (methylenetetrahydrofolate reductase) rs1801133 polymorphism leads to higher circulating levels of homocysteine, which is related to several liver diseases. We aimed to evaluate the relationship between MTHFR rs1801133 polymorphism and liver fibrosis progression in HCV-infected patients. Methods: We conducted a preliminary retrospective cohort study in 208 non-cirrhotic HCV-infected patients. These subjects had at least two liver stiffness measurements (LSM), which were assessed using transient elastography, and no patient had cirrhosis at baseline. We analyzed the association between MTHFR rs1801133 and outcome variables using Generalized Linear Models. Results: HCV-infected patients were 47 years old, around 54% were males, a low frequency of high alcohol intake (13.5%) or prior use of intravenous drugs (10.1%). A total of 26 patients developed cirrhosis (LSM1 ≥ 12.5) during a median follow-up of 46.6 months. The presence of the rs1801133 C allele showed an inverse association with the LSM2/LSM1 ratio (adjusted AMR = 0.90; 95%CI = 0.83-0.98; p = 0.020) and the cirrhosis progression (adjusted OR = 0.43; 95%CI = 0.19-0.95; p = 0.038). Besides, rs1801133 CT/CC genotype had an inverse association with the LSM2/LSM1 ratio (adjusted AMR = 0.80; 95%CI = 0.68-0.95; p = 0.009) and the cirrhosis progression (adjusted OR= 0.21; 95%CI = 0.06-0.74; p = 0.015). Conclusions: MTHFR rs1801133 C allele carriers presented a diminished risk of liver fibrosis progression and development of cirrhosis than rs1801133 T allele carriers. This statement supports the hypothesis that MTHFR rs1801133 polymorphism appears to play a crucial role in chronic hepatitis C immunopathogenesis.

An ethical framework for genetic counseling in the genomic era

The field of genetic counseling has grown and diversified since the profession emerged in the early 1970s. In the same period, genomic testing has become more complex, profitable, and widespread. With these developments, the scope of ethical considerations relevant to genetic counseling has expanded. In light of this, we find it helpful to revisit how ethical and relational variables are used to inform genetic counseling practice. Our specific focus is on whether, and to what extent, it is ethically acceptable for genetic counselors to make normative recommendations to patients. This article builds on prior literature that has critiqued nondirectiveness, a concept that has influenced and constrained the modern profession of genetic counseling since its origin. In it, we review scholarly efforts to move beyond nondirectiveness, which we believe privilege patient autonomy at the expense of other important values. We then argue that genetic counselors should favor a more explicit commitment to the principles of beneficence and non-maleficence, as well as a broader understanding of autonomy and the relational variables that impact genetic counseling. Finally, to translate our arguments into practice, we present a framework of six considerations that genetic counselors should take into account when deciding whether it is ethically acceptable, or even desirable, to make recommendations to patients in certain areas of their work.

Resident Training on Methylenetetrahydrofolate Reductase: a National Survey

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) is an enzyme important in folate metabolism. Genetic polymorphisms of MTHFR have potential clinical implications, particularly in treating mental disorders, where a biologically active form of metafolin is FDA approved in the treatment of major depressive disorder and schizophrenia. Therefore, residents in a variety of specialties must understand the link between genetic polymorphisms of MTHFR and clinical disorders.

OBJECTIVE

To identify current gaps in residency curricula with regards to the MTHFR gene.

METHODS

Using a snowball sampling method, a national online survey was sent to residency program directors in family medicine, internal medicine, and psychiatry to be forwarded to their corresponding residents. Data was collected between April 5, 2019, and May 14, 2019. Statistical tests included a Pearson chi-square test. Qualitative content analysis for open item responses was conducted in which recurring keywords and phrases were summarized. The primary outcome of interest was a dichotomous question: Does your curriculum teach about MTHFR?

RESULTS

The results showed that many of residency programs surveyed do not include MTHFR in their courses (family medicine 153/166, 92%; internal medicine 135/151, 89%; psychiatry 70/90, 78%) and a majority of residents are unaware of the clinical associations of MTHFR genetic polymorphisms with cardiovascular diseases and psychiatric disorders.

CONCLUSIONS

While many residents were aware of the MTHFR gene, knowledge about the gene was minimal and many curricula do not include MTHFR as part of their program. Therefore, we recommend residency training programs assess their level of training on MTHFR and its genetic polymorphisms.

Medical Decision Support to Reduce Unwarranted Methylene Tetrahydrofolate Reductase (MTHFR) Genetic Testing

Most major national medical associations have advised against routine MTHFR testing since at least 2013. However, many providers continue to order this unwarranted genetic test. This study assessed the efficacy of an electronic best practice alert to aid ordering providers. We tracked the rate of MTHFR tests ordered per 1 million patients in the twelve months before and after the implementation of an alert that suggested an alternative test. Associated factors including the ordering department, diagnosis, patient sex, and patient age were also analyzed. Chi square analysis was used to compare the difference between pre- and post-alert test ordering rates. A total of 997 MTHFR analysis were ordered in Southern California Kaiser Permanente from January 2017 through December 2018. Overall, the average MTHFR monthly test ordering rates dropped significantly from 12.93 per million patients in 2017 to 7.08 per million patients in 2018 (p = 0.0056). However, testing rates in children were unchanged and, in some associated diagnoses, such as psychiatric illnesses and neurodevelopmental conditions, the testing rates increased. Recommending an alternate test in lieu of the unwarranted one significantly reduced the overall rate of MTHFR testing. The alert was most effective for specialties and diagnoses where MTHFR was historically medically indicated. This suggests such alerts are an effective intervention that health care systems can implement to serve as an educational update and to reduce unwarranted genetic testing.

Machine Learning (ML) based-method applied in recurrent pregnancy loss (RPL) patients diagnostic work-up: a potential innovation in common clinical practice

RPL is a very debated condition, in which many issues concerning definition, etiological factors to investigate or therapies to apply are still controversial. ML could help clinicians to reach an objectiveness in RPL classification and access to care. Our aim was to stratify RPL patients in different risk classes by applying an ML algorithm, through a diagnostic work-up to validate it for the appropriate prognosis and potential therapeutic approach. 734 patients were enrolled and divided into 4 risk classes, according to the numbers of miscarriages. ML method, called Support Vector Machine (SVM), was used to analyze data. Using the whole set of 43 features and the set of the most informative 18 features we obtained comparable results: respectively 81.86 ± 0.35% and 81.71 ± 0.37% Unbalanced Accuracy. Applying the same method, introducing the only features recommended by ESHRE, a correct classification was obtained only in 58.52 ± 0.58%. ML approach could provide a Support Decision System tool to stratify RPL patients and address them objectively to the proper clinical management.

The Different Relationship between Homocysteine and Uric Acid Levels with Respect to the MTHFR C677T Polymorphism According to Gender in Patients with Cognitive Impairment

In an elderly population with cognitive impairment, we investigated the association between serum uric acid (sUA) and serum homocysteine (sHcy), known risk factors for cerebrovascular disease. We also investigated the potential effect of the C677T polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR) to the sUA level in different dementia types. Participants underwent a battery of tests including measurements of sUA, sHcy, folic acid, and vitamin B12 as well as genotyping of the MTHFR locus. Data from 861 subjects (597 females to 264 males) were retrospectively analyzed. Subjects with hyperhomocysteinemia had lower serum folic acid and vitamin B12 and higher sUA than those with normal sHcy. sUA was significantly associated with serum creatinine, HbA1c, and sHcy regardless of gender. The TT genotype was found to be associated with hyperhomocysteinemia in both genders (p = 0.001). The levels of hyperlipidemia, sHcy, and sUA differed according to dementia subtypes. High sUA were associated with hyperhomocystenemia in TT genotype only in dementia with vascular lesion. This study reveals that sUA is positively associated with sHcy. We speculate that the two markers synergistically increase cerebrovascular burden and suggested that dietary intervention for sUA and sHcy would be helpful for cognitive decline with vascular lesion.

The association between maternal methylenetetrahydrofolate reductase C677T and A1298C polymorphism and birth defects and adverse pregnancy outcomes

Published studies indicate the MTHFR C677T and A1298C polymorphisms are associated with abnormal homocysteine levels, which may cause various pregnancy complications and birth defects. However, the results obtained from different studies have been inconsistent. Therefore, this meta-analysis explores the association between MTHFR polymorphisms and birth defects and adverse pregnancy outcomes. The PubMed, ScienceDirect, Embase, and China Biology Medicine literature databases and ClinicalTrials were searched. Analyses of public bias, meta-regression, subgroups, and sensitivity were used to ensure the robustness of our results. MTHFR C677T was significantly associated with recurrent pregnancy loss in developing countries (odds ratio [OR], 1.34; 95% confidence interval [CI], 1.20-1.50) but not in developed countries (OR, 0.87; 95% CI, 0.68-1.11). No significant relationship was found between MTHFR A1298C and recurrent pregnancy loss (OR, 1.04; 95% CI, 0.93-1.18). MTHFR C677T and A1298C were not associated with preeclampsia (OR, 1.06; 95% CI, 0.97-1.16 and OR, 1.16; 95% CI, 0.97-1.39, respectively), and C677T was not associated with placental abruption (OR, 1.03; 95% CI, 0.87-1.21), intrauterine growth retardation (OR, 1.02; 95% CI, 0.90-1.15), or congenital heart disease (OR, 1.05; 95% CI, 0.89-1.25). MTHFR C677T, but not A1298C, was associated with neural tube defects (OR, 1.24; 95% CI, 1.08-1.42) and Down syndrome (OR, 1.65; 95% CI, 1.39-1.95). CONCLUSION: Although MTHFR C677T and A1298C are significantly associated with some types of congenital defects and adverse pregnancy outcomes, the impact of these polymorphisms is moderate.

CoDE-seq, an augmented whole-exome sequencing, enables the accurate detection of CNVs and mutations in Mendelian obesity and intellectual disability

Objective

The molecular diagnosis of extreme forms of obesity, in which accurate detection of both copy number variations (CNVs) and point mutations, is crucial for an optimal care of the patients and genetic counseling for their families. Whole-exome sequencing (WES) has benefited considerably this molecular diagnosis, but its poor ability to detect CNVs remains a major limitation. We aimed to develop a method (CoDE-seq) enabling the accurate detection of both CNVs and point mutations in one step.

Methods

CoDE-seq is based on an augmented WES method, using probes distributed uniformly throughout the genome. CoDE-seq was validated in 40 patients for whom chromosomal DNA microarray was available. CNVs and mutations were assessed in 82 children/young adults with suspected Mendelian obesity and/or intellectual disability and in their parents when available (n_total = 145).

Results

CoDE-seq not only detected all of the 97 CNVs identified by chromosomal DNA microarrays but also found 84 additional CNVs, due to a better resolution. When compared to CoDE-seq and chromosomal DNA microarrays, WES failed to detect 37% and 14% of CNVs, respectively. In the 82 patients, a likely molecular diagnosis was achieved in >30% of the patients. Half of the genetic diagnoses were explained by CNVs while the other half by mutations.

Conclusions

CoDE-seq has proven cost-efficient and highly effective as it avoids the sequential genetic screening approaches currently used in clinical practice for the accurate detection of CNVs and point mutations.

•

Whole-exome sequencing (WES) poorly detects CNVs.

•

Whole-genome sequencing remains expensive and hard to handle in clinical practice.

•

CoDE-seq (based on an augmented WES protocol) accurately detect CNVs.

•

CoDE-seq is highly effective for the diagnosis of obesity & intellectual disability.

Methylenetetrahydrofolate reductase gene C677T and A1298C polymorphisms and susceptibility to recurrent pregnancy loss

Several studies have investigated the link between two different polymorphisms (C677T and A1298T) of the gene encoding methylenetetrahydrofolate reductase (MTHFR) and the risk of recurrent pregnancy loss (RPL); however, the results remain controversial. This study aimed to provide greater insight into this debated topic. In the current study, two groups of pregnant women (group A: RPL women; group B: non-RPL women), each of which were subdivided further into two subgroups based on their gestational age, were screened for C677T and A1298T variants of the MTHFR gene. The resulting data were analyzed using receiver operating characteristic (ROC) curve and Z test methods to compare the two groups. These ROC curve and Z test analyses indicated that there were no differences between the groups regarding C677T and A1298T expression. RPL is primarily caused by mutations in prothrombin or factor V Leiden genes. However, a low percentage of RPL cannot be attributed to these mutations. In the last five years, research has focused on the MTHFR gene, the two major variants of which (C677T and A1298T) have been associated with an increased risk of cardiovascular diseases (thrombotic events) in homozygous individuals. In addition, these mutations may be related to an increased rate of neural tube defects in fetuses. While a link between MTHFR mutation and RPL may be expected based on previous findings, the present study indicated the absence of an association between the polymorphisms of the MTHFR gene and RPL risk.

Expanded carrier screening in gamete donors of Venezuela

OBJECTIVE

To discuss the implications of expanded genetic carrier screening for preconception purposes based on our practice.

METHODS

One hundred and forty-three potential gamete donors aged 20-32 years old (µ=24, 127 females and 16 males), signed informed consent forms and were selected according to the REDLARA guidelines. Blood or saliva samples were examined by one of these genetic carrier screening methods: Genzyme screening for Cystic Fibrosis (CF), Fragile X and Spinal Muscular Atrophy (SMA); Counsyl Universal panel or Recombine Carrier Map.

RESULTS

Genotyping results for all donors were analyzed; 41% (58/143) of donors were identified as carriers for at least one condition. We found a carrier frequency of 1/24 for CF, 1/72 for SMA and 0/120 for Fragile X syndrome. Among the high-impact most prevalent conditions in our study (Carrier Map group) were: 21-Hydroxilase-Deficient Congenital Nonclassical Adrenal Hyperplasia (1/8), Factor V deficiency (1/12), Hemochromatosis: Type 1: HFE Related (1/12), Short Chain Acyl-CoA (1/14) and MTHFR deficiency 1/3 (39%).

CONCLUSIONS

The rate of gamete donors identified as carriers of at least one condition was 41%, which supports the offering of expanded carrier screening to our population. Studies in Latin American populations could help customize screening panels. The ART patient population has a unique opportunity to be offered expanded carrier screening and appropriate counseling, to make its best-informed decisions.

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.

Systems biology of personalized nutrition

Personalized nutrition is fast becoming a reality due to a number of technological, scientific, and societal developments that complement and extend current public health nutrition recommendations. Personalized nutrition tailors dietary recommendations to specific biological requirements on the basis of a person's health status and goals. The biology underpinning these recommendations is complex, and thus any recommendations must account for multiple biological processes and subprocesses occurring in various tissues and must be formed with an appreciation for how these processes interact with dietary nutrients and environmental factors. Therefore, a systems biology-based approach that considers the most relevant interacting biological mechanisms is necessary to formulate the best recommendations to help people meet their wellness goals. Here, the concept of "systems flexibility" is introduced to personalized nutrition biology. Systems flexibility allows the real-time evaluation of metabolism and other processes that maintain homeostasis following an environmental challenge, thereby enabling the formulation of personalized recommendations. Examples in the area of macro- and micronutrients are reviewed. Genetic variations and performance goals are integrated into this systems approach to provide a strategy for a balanced evaluation and an introduction to personalized nutrition. Finally, modeling approaches that combine personalized diagnosis and nutritional intervention into practice are reviewed.