Long-term follow up of a new case of hawkinsinuria

Hawkinsinuria is a rarely diagnosed autosomal dominantly transmitted inborn error of tyrosine metabolism with impaired conversion of 4-hydroxyphenylpy ruvate to homogentisate. As a consequence of the defective 4-hydroxyphenylp yruvate dioxigenase activity, large amounts of the unusual, ninhydrin-posit ive amino acid hawkinsin and later on in life 4-hydroxycyclohexylacetic aci d are formed and excreted. Clinically the disease is characterised mainly b y chronic metabolic acidosis and severe growth retardation as a result of p rotein overload. As the ability to form 4-hydroxycyclohexylacetic acid and thereby to cope with the still not very well defined reactive and toxic int ermediates increases, clinical symptoms vanish. We report here a new patien t with hawkinsinuria having experienced a series of admissions because of u nclear hepatopathy, growth retardation, and renal tubular acidosis. Conclusion Prolonged tyrosyluria in the newborn and young baby should cause the clinical chemist not only to exclude tyrosinaemia, galactosaemia, and fructose intolerance but also to look carefully for hawkinsin in the aminoa cid chromatogram.