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

Table 2 Urinary organic acid analysis results

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

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).

ISSN: 1750-1172