Deficiency of Fumarylacetoacetase in the Acute Form of Hereditary Tyrosinemia with Reference to Prenatal Diagnosis
The terms tyrosinemia and tyrosinosis have been widely used to describe at least seven distinct disorders of tyrosine metabolism associated with diverse clinical and biochemical consequences in infants, children and even adults (1). The only consistent biochemical abnormality within these syndromes has been the finding of elevated levels of plasma tyrosine, a non-essential amino acid derived from phenylalanine by the action of the enzyme phenylalanine hydroxylase. In most of the reported patients with tyrosinemia the clinical presentation resembled that of acute liver failure (acute infantile stage) while later manifestations (chronic stage) included liver cirrhosis, multiple renal tubular dysfunction, hypophosphatemic rickets and porphyria-like symptoms. Other less frequent modes of presentation were mental retardation, skin and corneal dystrophies and metabolic acidosis, without liver involvement. The major characteristics of the most common forms of tyrosinemia are outlined in Table I. For the purpose of this presentation, we will restrict our discussion to hereditary tyrosinemia.
KeywordsAmniotic Fluid Corneal Dystrophy Homogentisic Acid Acute Intermittent Porphyria Tyrosine Metabolism
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