Unclear symptoms, early diagnosis and perfect outcome: a case diagnosed as sepiapterin reductase deficiency hidden behind vitamin B12 deficiency

J Pediatr Endocrinol Metab. 2024 Dec 31;38(2):196-200. doi: 10.1515/jpem-2024-0515. Print 2025 Feb 25.

Abstract

Objectives: Sepiapterin reductase deficiency (SRD) is a rare dopa-sensitive neurotransmitter disorder caused by autosomal recessive mutations in the sepiapterin reductase gene. The triad of paroxysmal stiffening, oculogyric crises, and hypotonia are highly suggestive in some patients. However, in other patients, the clinical picture may be nonspecific and remain under-recognized and misdiagnosed as cerebral palsy.

Case presentation: We present a nine-month-old boy who initially presented with hypotonia and developmental delay, diagnosed as vitamin B12 deficiency. Upon he did not respond to vitamin replacement treatment, he was diagnosed with SRD by whole-exome sequencing (WES). The boy improved dramatically under treatment with L-dopa, 5-hydroxytryptophan and BH4.

Conclusions: We aim to emphasize that SRD can present with nonspecific symptoms, leading to a diagnostic delay for this rare but treatable disease. Moreover, our case is the first to demonstrate the clinical benefit of BH4 add-on treatment. Early intervention is crucial for good outcome and neurodevelopment.

Keywords: BH4 add-on treatment; hypotonic infant; sepiapterin reductase deficiency; vitamin B12 deficiency.

Publication types

  • Case Reports

MeSH terms

  • Alcohol Oxidoreductases / deficiency
  • Alcohol Oxidoreductases / genetics
  • Biopterins / analogs & derivatives
  • Biopterins / deficiency
  • Biopterins / therapeutic use
  • Diagnosis, Differential
  • Early Diagnosis*
  • Humans
  • Infant
  • Levodopa / therapeutic use
  • Male
  • Prognosis
  • Vitamin B 12 Deficiency* / complications
  • Vitamin B 12 Deficiency* / diagnosis
  • Vitamin B 12 Deficiency* / drug therapy
  • Vitamin B 12 Deficiency* / genetics

Substances

  • Alcohol Oxidoreductases
  • sepiapterin reductase
  • Levodopa
  • Biopterins
  • sapropterin