Exploring the impact of methylenetetrahydrofolate reductase (MTHFR) gene variations on autism spectrum disorder severity

Study design and participants

This study was approved by the Institutional Review Board (IRB) of Cayuse IRB, ensuring compliance with ethical guidelines for research involving human participants (Approval Number: PRO-2022-198, Date: 7/5/2022). This study occurred from July 2023 to September 2023. A retrospective chart review was performed. The review included an analysis of previous psychiatric evaluations, previous diagnoses, and physician notes from previous visits.

Participants included individuals from Rowan’s Regional Integrated Special Needs (RISN) Center diagnosed with ASD who had undergone MTHFR genetic testing through Genomind. Genomind is a precision health company specializing in personalized medicine through pharmacogenetic testing. They integrate genetic, environmental, and lifestyle factors to optimize patient treatment, particularly in mental health. Their solutions aim to enhance medication management by providing healthcare providers with genetic insights to individualize patient care [9]. Genomind classifies MTHFR activity into four levels: low/absent, low to intermediate, intermediate, and high/normal. This is determined through assessing whether a patient has the common mutations of their MTHFR genes: C677T and A1298C on chromosome 1 [2], 10], 11].

Genomind utilizes an SNP panel to determine mutations in the MTHFR gene. A C677T mutation reduces the enzymatic activity of MTHFR by approximately 35 % per T allele, and a A1298C mutation reduces the enzymatic activity of MTHFR by approximately 20 % per C allele [9]. These decreases were categorized by Genomind into the four levels described previously. Calculation of the percent of MTHFR activity decrease leads to category 4 having a 0–20 % decrease, category 3 having a 21–35 % decrease, category 2 having a 36–55 % decrease, and a category 1 having a 56–70 % decrease.

Assessment of MTHFR and ASD severity

MTHFR levels were assigned numeric values from 1 to 4 in conjunction with the previous Genomind classification [9]:

1. Low/absent

2. Low to intermediate

3. Intermediate

4. High/normal

ASD severity was assessed utilizing DSM-5 criteria [1], with the levels defined as follows:

1. Level 1=Requires little support

2. Level 2=Requires substantial support

3. Level 3=Requires very substantial support

Each patient was given an ASD severity level according to the qualifications from the DSM-5. ASD severity assessments were made by two medical students and confirmed by a treating psychologist (W.A.) and physician (A.I.), based on comprehensive reviews of medical and psychiatric records. Initially, there were 215 subjects in the study from the RISN Center that had Genomind studies performed. Thirty-one patients with MTHFR deficiencies but without an ASD diagnosis were excluded from the analysis, and 106 patients with an ASD diagnosis but without a Genomind analysis were also excluded from the analysis. The number of participants in the study was 78 once the patients were selected for having both an ASD diagnosis and had MTHFR testing performed.

Data analysis

Data analysis involved performing statistical comparisons between ASD severity levels utilizing analysis of variance (ANOVA), with significance defined at p<0.05. The ANOVA utilized the MTHFR levels assigned through Genomind for each patient in a specific ASD category. The average age in years of subjects was also calculated for each ASD severity category along with the age range, number of males, and number females.

Contextualizing findings

The observed correlation between reduced MTHFR activity and ASD severity adds to the growing body of evidence emphasizing the role of metabolic and genetic pathways in neurodevelopmental disorders. While our findings corroborate prior research, they also provide a more specific understanding of the clinical implications of MTHFR activity in ASD severity. For example, our study highlights not only the existence of this correlation, but also the potential for utilizing MTHFR activity levels as a biomarker to stratify risk and guide interventions.

Clinical applications

These insights are clinically significant, because they pave the way for personalized interventions. We theorize that screening for MTHFR variants at the time of ASD diagnosis or even during infancy could allow for earlier interventions to mitigate symptom severity. Early treatment strategies might include targeted nutritional support or other therapies to address MTHFR deficiencies, potentially improving long-term outcomes for individuals with ASD. Such an approach would be especially valuable for osteopathic physicians, who often emphasize holistic and preventative care.

Comparison with previous studies

Our findings are consistent with earlier studies that have linked folate metabolism and neurodevelopment, but they differ in providing quantitative evidence of how MTHFR activity correlates with ASD severity. Unlike prior research that primarily explored MTHFR variants qualitatively, our study quantifies their impact, offering a new dimension to understanding their clinical relevance.

Limitations

Several limitations of this study must be acknowledged. First, the sample size of 78 participants, while sufficient to detect significant correlations, limits the generalizability of our findings. This small sample size also means that any conclusions drawn from this study are limited and may be misleading in future studies. Second, the cross-sectional design of the study precludes us from drawing causal conclusions about the relationship between MTHFR activity and ASD severity. Third, potential confounding factors, such as environmental influences and comorbid conditions, were not fully accounted for in our analysis. This is mainly due to the complex nature of the confounding factors and the difficulty quantifying their impact on the data. Future longitudinal studies with larger and more diverse cohorts are needed to validate our findings and explore these additional variables.