Autosomal Recessive Guanosine Triphosphate Cyclohydrolase I Deficiency: Redefining the Phenotypic Spectrum and Outcomes.

The clinical spectrum of arGTPCH deficiency is a continuum from early-onset encephalopathies to classical DRD. Genotype and biochemical alterations may allow early diagnosis and predict clinical severity. Early treatment remains critical, especially for the most severe patients.