Hypertryptophanemia (HYPTRP) is a rare inherited metabolic disorder caused by congenital defects of tryptophan metabolism. Tryptophan is a precursor to the neurotransmitters serotonin and melatonin. It has been described that some patients had growth and developmental delay, ataxia, and photosensitive skin rash. Recently, HYPTRP due to tryptophan 2,3-dioxygenase deficiency has been reported.
