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Table 2 Urinary organic acid analysis results

From: A novel mutation causing mild, atypical fumarylacetoacetase deficiency (Tyrosinemia type I): a case report

Age 4 months 5 months 8 months 18 months
Succinylacetone 0.2 0.1 0.1 ≈ 0.1
Succinylacetoacetate ≈ 0.1 <0.1 ≈ 0.3 <0.1
4-oxo-6-hydroxyheptanoic acid 4 1 2 8
creatinine, mmol/L 3.1 1.6 3.1 3.2
  1. A significantly increased excretion of aberrant tyrosine metabolites was detected, with 4-oxo-6-hydroxyheptanoic acid as the dominant metabolite. The excretion of phenolic tyrosine metabolites was not significantly increased: in the first sample 4-hydroxyphenylpyruvate was 7 mmol/mol creatinine, which can be considered as marginally increased (ref value in newborns <10, in infants <5). In later samples, we found 4-hydroxyphenylpyruvate <1 mmol/mol creatinine (reference value <5) and 4-hydroxyphenyllactate 2 mmol/mol creatinine (reference value < 10). These values are in accordance with a normal 4-hydroxyphenylpyruvate dioxygenase activity (Table 1).