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Wednesday, Dec 03, 2008 | 12:00 PM
Madisons Foundation - Moms And Dads In Search Of Needed Support
Hawkinsinuria
4-hydroxyphenylpyruvate hydroxylase deficiency,
4-hydroxyphenylpyruvate dioxygenase deficiency
Thursday, 28 July 2005
Last Updated Thursday, 28 July 2005
What
Hawkinsinuria is an autosomal dominant genetic disorder medically classified as a tyrosinemia due to an inborn error of amino acid metabolism. Children with this disease have a mutation in one of the enzymes responsible for breaking down tyrosine, an amino acid, in the body. The mutation decreases the function of the enzyme, called 4-hydroxyphenylpyruvate hydroxylase. This results in the accumulation of hawkinsin, an amino acid metabolite (degradation product), in the child’s blood which is responsible for the symptoms. It is excreted in the urine.Who
Hawkinsinuria is usually detected in the newborn soon after they stop breast-feeding or when they begin taking formula. It is a rare disease with an estimated incidence of less than 1 per 100,000 people. It occurs equally in both males and females.Signs and Symptoms
Children with hawkinsinuria often do not show symptoms. However, symptomatic children may present with one or more of the following: - emitting an odd odor described as a “swimming pool” odor - enlarged liver - failure to thrive (failure to gain weight) - diminished activity or irritability - hair abnormality, where the hair is fine, fair, sparse and/or stubby - short stature Degree of symptoms appears to be dependent upon the quantity of protein ingested during infancy; the greater the protein intake, the greater the clinical symptoms.Possible Causes
The body uses dietary amino acids for growth, energy and to build other molecules. The body needs to metabolize (break down) the amino acids and it does so by many chemical reactions. These reactions depend on enzymes that turn the original amino acid into different subsequent chemicals (which are referred to as metabolites). In tyrosine metabolism, one of the enzymes that is required is the 4-hydroxyphenylpyruvate hydroxylase (aka 4-hydroxyphenylpyruvate dioxygenase). In Hawkinsinuria, the mutation in this enzyme affects its activity so that when its turn comes to facilitate the chemical reaction, it is unable to do so, and the metabolic process does not continue normally. Ultimately, this failure results in the accumulation of an organic acid called hawkinsin which is responsible for the symptoms of Hawkinsinuria.Diagnosis
Laboratory tests show certain general findings. Since these infants have a metabolic acidosis their blood will be acidic. Also, tyrosine metabolites like hawkinsin are detected in their urine. The hawkinsin acid is detected by a specific test called gas chromatography-mass spectrometry (GC-MS).Treatment
A low protein diet and a diet low in the amino acids phenylalanine and tyrosine improve the symptoms. After about 1 year of age, this restriction can be discontinued as tolerance to these amino acids occurs and a regular diet no longer causes symptoms.Prognosis
Long-term prognosis is very positive. Once treated, children usually develop normally both physically and mentally.Connect with other parents
In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.Weblinks
There are few weblinks that discuss Hawkinsinuria, but below are websites that provide information on tyrosinemia. Children with Hawkinsuria have much less severe symptoms compared to hereditary tyrosinemia and do not require liver transplantation.
MSN Support Group
A support group on the Microsoft network. This site allows you to connect to others affected by Hereitary Tyrosinemia. It also has information about the disease as well as links to other good sites.
Liver Kids
A nice website with information about the tyrosinemia as well as links to other informative sites. There is also information about liver donations on this site.
CLIMB (Children Living with Inherited Metabolic Diseases)
British website that provides little information on Hawkinsuria but has support information and newsletters for children with metabolic diseases.