The positive predictive value of HT in newborn screening was 3.4%.The case of HT1,with 666.9 μmol/L of screening TYR and 3.87 μmol/L of SA values, appeared with cholestasis, mild elevated of liver enzyme and lactic acid and died at 2 months old even with medical milk powder (tyrosine and phenylalanine free).The case of HT2, with 625.6 μmol/L of screening TYR and normal SA, has normal score of Bayley assessment with medical milk treatment. This evidence concerns the gene TYR and cholestasis.