Column 1 shows the result of a first biopsy in the presented patient (at diagnosis), the second column of a confirmatory biopsy in the same patient. Column 3 shows the results in a type III tyrosinemia, for comparison. The last column shows control values. FAH is clearly decreased, but measurable in both biopsies in our patient (approx. 5% of normal). 4-HPD is unexpectedly not equally decreased as would be expected in type I tyrosinemia, also contrasting with the value measured in the type III tyrosinemia biopsy. The fact that 4-HPD is not decreased, is compatible with the absence of SA and SAA in our patient. ASAT, ALAT and LDH are internal controls, demonstrating the quality of the tissue samples used.