High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the...

Seryl-tRNA synthetase 1 (SARS1) deficiency is a rare autosomal recessive disorder presenting with neurodevelopmental delay, deafness, cardiomyopathy, and fatal metabolic decompensation triggered by febrile episodes. While amino acid chronic supplementation is established, no guidelines exist for acute management. We report the case of a 9-year-old male of Turkish origin with genetically confirmed SARS1 deficiency, admitted with fever, vomiting, hypotonia, and seizures. The clinical course rapidly progressed to metabolic decompensation and severe acute cardiac failure, characterised by a left ventricular ejection fraction of 20%, necessitating mechanical ventilation and vasopressor support. Notably, the patient's family history included the death of three siblings during similar febrile episodes. During hospitalisation, the patient's specific L-serine supplementation dosage was progressively tripled concurrently with standard supportive care. Unlike the fatal outcomes observed in his siblings, untreated by L-serine, the patient survived and recovered following this high-dose regimen. Cardiac biomarkers normalised within 20 days, and follow-up echocardiography at 1 month demonstrated complete resolution of myocardial oedema. However, a year later, the patient presented with another febrile crisis at 10 years old, and despite an emergency protocol, the patient developed severe biventricular dysfunction progressing to fatal cardiogenic shock. This constitutes the first documented survival of a SARS1-related metabolic crisis managed with high-dose L-serine. The findings strongly suggest that early, aggressive escalation of L-serine dosage can be a viable therapeutic strategy for acute decompensation in SARS1 deficiency.