Abstract
Abstract Isolated sulfite oxidase deficiency (ISOD) is a devastating, neurometabolic disorder caused by mutations in the SUOX gene necessary for the final step in the sulfur-containing amino acid catabolic pathway. Patients classically present in the neonatal period with neurologic manifestations. Biochemical findings include elevated sulfocysteine, low cystine and undetectable homocysteine with normal uric acid levels. Other associated biochemical markers include elevated plasma alpha-aminoadipic semialdehyde and piperideine-6-carboxylic acid. We report a patient with classic neonatal onset ISOD (refractory seizures, hypertonicity, brain abnormalities, pathogenic SUOX mutations). Her clinical course was marked by extreme irritability, prompting the use of a low methionine and cystine diet to decrease toxic metabolites thought to be contributing to her symptoms. Biochemical markers and extreme irritability improved with dietary treatment (methionine=30mg/kg/day). She died of sepsis in early infancy, precluding long term follow-up. This case reviews the potential benefits and limitations of diet therapy in this rare disorder.
Highlights
Case ReportA term female infant was born by spontaneous vaginal delivery to Hispanic primigravida parents without known consanguinity
Isolated sulfite oxidase deficiency (ISOD) is a devastating, neurometabolic disorder caused by mutations in the SUOX gene necessary for the final step in the sulfur-containing amino acid catabolic pathway
While most authors report no long term benefit with dietary treatment for patients with a classic phenotype, 1,2,6 patients with a milder disease may benefit . 1,7,8 We report a new case of severe neonatal ISOD, describing its clinical course, magnetic resonance imaging (MRI)
Summary
A term female infant was born by spontaneous vaginal delivery to Hispanic primigravida parents without known consanguinity. A repeat ophthalmology exam at 3 weeks of age was improved and did not demonstrate ectopia lentis She was initially NPO on admission and when enteral feedings were established she was fed breastmilk. At 2 1⁄2 weeks of age, feedings were stopped due to intolerance and concern for necrotizing enterocolitis (bilious residuals, abdominal distention), requiring a prolonged NPO period for bowel rest and total parenteral nutrition (TPN) support. Her hospital course was marked by extreme irritability during this period, that required frequent morphine administration. Nutrition Source Methionine mg/kg/day (U) sulfocysteine (U) xanthine (U) hypoxanthine (P) homocysteine (P) cystine (P) methionine (P) uric acid (P) AASA (P) P6C
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