Hepatorenal Tyrosinemia (HRT, OMIM 276700) is an autosomal recessive inborn error of metabolism which mainlyaffects the liver, kidneys and peripheral nerve. The primary defect has been attributed to the last enzyme in the catabolic pathway of tyrosine: fumarylacetoacetate hydrolase (FAH: E. C. 184.108.40.206). Early diagnosis and timely treatment offers an improved prognosis of the tyrosinemic patients. This treatment would require an administration of 2-(2-nitoro-4-trifluoromethylbenzoyl)-1, 3-cyclohexanedione (NTBC, OrfadinÒ), a low phenylalanine and tyrosine diet, and liver transplantation.
Since several years, our laboratory carry out the diagnosis and the biological follow-up of tyrosinemic of all the own territory. In this report, we summarize the biochemical phenotype of 58 infants with HRT, focusing on the laboratory findings. The 58 infants (30 boys and 28 girls and 16 boys) came from 54 different families. The age at onset of the first symptoms of the disease varied from one week to four months, Thirty three patients died in the same month that the diagnosis was established, and twenty five are actually followed up after NTBC therapy and restriction diet. Elevated concentration of succinyl acetone in the urine, hypertyrosinemia and raised a-fetoprotein level were the most common indicators at the diagnosis. Urinalysis revealed no proteinuria, no cetonuria but sometimes glycosuria. Galactose and ferric chloride tests were negative. Positive reactions with 2, 4-dinitrophenyl hydrazine and cyanide-nitroprusside were observed occasionally. Only five urine specimens presented peculiar odour.
All patients showed hyperbilirubinemia (both direct and indirect bilirubin) and deterioration of liver function (elevated ASAT, ALAT and slightly increazed PAL and GGT).
Increased plasma ferritin and b2-microglobulin levels were seen intwenty four and five infants respectively.
However, fast plasma glucose, total cholesterol, triglycerides, albumin and proteins concentrations were either normal or slightly decreased.
HRT did not affect serum creatinine, urea, calcium, phosphorus and blood ammonia levels.