[Evolution of a case of tyrosinemia type I treated with NTBC]

Tyrosinemia type I is an autosomal recessive inherited disorder caused by deficient fumarylacetoacetase activity. Treatment with 2-(2-nitro-4-trifluoro-methylbenzoyl)-1,3-cyclohexanedione (NTBC), an inhibitor of 4-hydroxyphenylpyruvate dioxygenase, has successfully been applied for the last few years. Our aim was to evaluate the clinical and biochemical response to treatment with NTBC of a 18-year-old patient with a chronic form of tyrosinemia type I, whose main clinical feature was vitamin D-resistant rickets leading to severe osteoporosis with multiple bone fractures and skeletal deformities. After treatment, toxic metabolites became undetectable and porphobilinogen synthase activity returned to normal. Renal function improved, blood hemoglobin returned to normal and alfa-fetoprotein decreased. The patient's general condition greatly improved. However, the alfa-fetoprotein concentration slowly increased during the second year of NTBC treatment and hepatocellular carcinoma developed. NTBC treatment should be considered even in advanced cases of tyrosinemia type I, although only as a palliative therapy.