<unk>  is considered benign as most patients remain asymptomatic, early correlational evidence from the first decade of<unk>  research lead to the theory that<unk>  was associated with multiple developmental symptoms including hyperactivity, speech impediment, developmental delay, learning difficulties, and sometimes mental retardation. However, these claims were later deemed coincidental as a large subpopulation of infants that tested positive for<unk>  were found to have normal IQ and speech characteristics; as such<unk>  has since been reclassified as a benign inborn error of metabolism.
Histidinemia
Isovaleric acidemia
Pipecolic acidemia
Galactosemia
Hyperphenylalaninemia
D-Glyceric acidemia
Hypoplasminogenemia
Hawkinsinuria