SPR Deficiency (Biopterin Deficiency)

Sepiapterin reductase deficiency is a disorder of tetrahydrobiopterin metabolism. Tetrahydrobiopterin plays a role as a cofactor in Phenylalanine, L-Dopa and Serotonin metabolism. Only a few patients have been described with Sepiapterin reductase deficiency. They had various degrees of developmental delay / intellectual disability and developed L-Dopa responsive dystonia with diurnal variation (Segawa syndrome). Sepiapterin reductase deficiency does not go along with elevated blood phenylalanine levels and thus is not detected via newborn screening for hyperphenyalaninemias.

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