Guthrie's bacterial inhibition test:- Screening test for phenylketonuria (PKU) Used to detect the abnormal presence of phenylalanine metabolites in blood i.e. Phenyl pyruvate Phenyl alanine Phenyl lactate. Procedure: A small amount of blood sample is taken from heel of the infant and placed in a medium with a strain of Bacillus subtilis, a bacteria that cannot grow without phenylalanine. If phenylalanine metabolites are present, then these bacteria reproduce, and the test result is positive,indicating that patient has PKU. Benedict's test Benedict's reagent(blue in color) is taken in a test tube and the urine sample is added to it | Then the test tube is heated. | If color changes to green, orange or brick red then it shows a positive test for reducing sugar. GALT assay- used for galactosemia. Mutation analysis- can be used for mutation detection, or as a confirmation of next generation sequencing and microarray results.