Researchers discovered that adding the amino acid tyrosine to the diet, combined with eating more protein, may help children with a rare genetic condition called YARS1 deficiency. This condition affects how the body uses one of the building blocks needed to make proteins. In a small study of nine children, eight showed improvements in movement, coordination, and behavior after receiving tyrosine supplements. Some children also gained weight and stopped vomiting. While this is early research on a very rare disease, the results suggest this simple dietary approach could be a safe and effective treatment worth trying.

The Quick Take

  • What they studied: Whether adding tyrosine (a protein building block) to the diet helps children with YARS1 deficiency, a rare genetic disorder that affects how the body makes proteins and develops normally.
  • Who participated: Nine children with YARS1 deficiency. Seven received tyrosine supplements plus a high-protein diet, while two received tyrosine supplements alone.
  • Key finding: Eight out of nine children showed improvements in movement, coordination, and behavior after receiving tyrosine supplements. Six gained weight, all stopped vomiting, and some showed improvements in blood counts.
  • What it means for you: If you or a family member has YARS1 deficiency, this research suggests that tyrosine supplementation combined with a high-protein diet may be worth discussing with your doctor. However, this is early research on a very rare condition, so more studies are needed to confirm these results.

The Research Details

This was a small case study where researchers followed nine children with YARS1 deficiency who received tyrosine supplements. Seven children also followed a high-protein diet. The researchers tracked changes in the children’s behavior, movement, weight, and other health markers over time. They also tested how well tyrosine supplements worked in cells taken from some of the patients to understand the biology behind the treatment.

The study combined two types of information: real-world observations of how the children improved, and laboratory experiments showing how tyrosine affects the faulty protein in these patients’ cells. This combination helps researchers understand both whether the treatment works and why it might work.

YARS1 deficiency is an extremely rare genetic disorder, so it’s difficult to study. Large clinical trials with hundreds of patients aren’t possible. This case study approach allows doctors to carefully document what happens when patients receive a new treatment, which is valuable for rare diseases. The laboratory work helps explain the mechanism, making the findings more credible.

This is a small study of only nine patients, which is a significant limitation. The study lacks a control group (children who didn’t receive the treatment) for comparison. However, the improvements were substantial and consistent across most patients. The laboratory work provides biological evidence supporting the findings. Because YARS1 deficiency is so rare, this represents a meaningful contribution to the medical literature, though larger studies would strengthen the conclusions.

What the Results Show

The most striking result was improvement in movement and coordination: eight out of nine children showed better cooperation, endurance, and motor skills after starting tyrosine supplements. This suggests the treatment helps the nervous system function better.

All nine children stopped vomiting after receiving tyrosine supplements, which is a significant quality-of-life improvement. Six out of nine children gained weight, indicating the treatment may help with growth and nutrition.

Four out of nine children showed improvements in their blood counts, suggesting the treatment may help the bone marrow produce blood cells more effectively. Two children showed progress in developing language skills, though this was less consistent than the movement improvements.

In the laboratory, when researchers increased tyrosine levels in patient cells from 100 to 500 micromoles (a five-fold increase), the faulty protein’s activity improved dramatically, approaching normal levels. This explains why higher doses of tyrosine supplementation might be necessary.

Beyond the main improvements, the research showed that different genetic variations of YARS1 may respond differently to treatment. Some patients’ cells showed better recovery of protein function than others at the same tyrosine dose. This suggests that future treatment plans may need to be personalized based on which specific genetic mutation a patient has.

Similar amino acid supplementation strategies have worked for other rare genetic disorders affecting protein synthesis. This research extends that approach to YARS1 deficiency, suggesting a general principle: when the body can’t properly use a specific amino acid due to a genetic defect, supplementing that amino acid may help compensate. The findings align with how other aminoacyl-tRNA synthetase deficiencies have been treated.

The study included only nine children, which is very small. There was no control group of children who didn’t receive treatment, so we can’t be completely certain the improvements were caused by the supplement rather than other factors. The follow-up period wasn’t specified, so we don’t know how long the benefits lasted. The study didn’t compare tyrosine supplementation alone versus tyrosine plus high-protein diet in a systematic way. More research with larger groups and longer follow-up is needed to confirm these preliminary findings.

The Bottom Line

For patients with confirmed YARS1 deficiency: Tyrosine supplementation combined with a high-protein diet appears to be a reasonable treatment option worth discussing with your genetic specialist or metabolic disease doctor. The evidence is preliminary but promising, with a good safety profile. Start with medical supervision to determine the right dose for your specific genetic variant. Moderate confidence level—this is early research, but the results are encouraging enough to warrant clinical trials.

This research is specifically relevant to families with children diagnosed with YARS1 deficiency. Genetic counselors and metabolic disease specialists should be aware of this potential treatment option. Parents of children with other rare genetic disorders affecting protein synthesis may also find this research relevant as it demonstrates a general treatment principle. This research is not applicable to the general population.

Based on this study, improvements in movement and coordination appeared relatively quickly after starting supplementation. Vomiting stopped in all cases, suggesting rapid symptom relief. Weight gain took longer to develop. Long-term benefits and whether improvements continue indefinitely are unknown and require further study. Expect to see initial changes within weeks, but plan for ongoing monitoring over months.

Want to Apply This Research?

  • Track daily tyrosine supplement dose and timing, protein intake (grams per day), and weekly measurements of: movement/coordination improvements (using a simple 1-10 scale), vomiting episodes (count per week), and weight (weekly weigh-ins). Note any changes in behavior, language development, or energy levels.
  • Users can log their daily tyrosine supplement intake and high-protein food choices. The app could provide reminders for supplement timing and suggest high-protein meal options. Users can rate their child’s energy, coordination, and behavior daily to track improvements over time.
  • Create a weekly dashboard showing supplement adherence, protein intake trends, and a composite score of symptom improvements. Set monthly check-in reminders to review progress with the medical team. Track any side effects or concerns. Generate monthly reports to share with healthcare providers to inform dose adjustments.

This research describes a promising early-stage treatment for YARS1 deficiency, an extremely rare genetic disorder. These findings are based on a small study of nine patients and should not be considered definitive medical advice. If you or a family member has YARS1 deficiency, discuss tyrosine supplementation with your genetic specialist or metabolic disease physician before starting any new treatment. Do not start tyrosine supplements without medical supervision, as appropriate dosing may vary based on individual genetic mutations and other health factors. This summary is for educational purposes and does not replace professional medical diagnosis or treatment.