Phenylketonuria (PKU) is an inability to clear excess of the amino acid phenylalanine that, if left untreated, leads to brain dysfunction and intellectual disability. PKU is an inherited metabolic disease that is screened for in infancy in all 50 states and D.C., and is found most frequently in newborns. Variation exists between state laws mandating consistent coverage of low-phenylalanine dietary products for both private and state-run health insurances. Missouri law (RSMo § 191.331) provides for the screening of PKU at birth through fee-maintained screening programs, and for treatment via baby formula through the Metabolic Formula Program. Additional legislation has been proposed that would require health insurances to cover all PKU patients for dietary products for the disease through the age of six.