Tyrosinemia Type I

I don’t know if I have mentioned it before, but I am in Genetics this semester and we are doing research on genetic disease and different studies relating to them. As I was looking up some information to put on the web page for the class I came across an interesting article that described a study that compared tests for tyrosinemia type I. Before describing the study though here is some background information on the disease. Tyrosinemia type I is a hereditary metabolic genetic disorder that results from deficiency of the enzyme fumarylacetoacetate hydrolase (FAH) that breaks down tyrosine. It generally presents within the first few months following birth but could take up to a year before symptoms are noticed. The lack of FAH causes toxins to build up in the liver and causes liver and renal tubular dysfunction. If the patient is not diagnosed or does not receive treatment, then death usually results within the first ten years of life. It is estimated that one to two million people are affected by the disorder; in the United States in occurs in 1 in 100,000 babies. For each person the symptoms are varied and range from mild to nearly uncontrollable, but with proper treatment individuals can maintain normal lifestyle. The study was the “Preliminary proficiency testing results for succinylacetone in dried blood spots for newborn screening for tyrosinemia type I” and it focused on testing for the disease rather than treatment. It is estimated that only 50% of patients are diagnosed with tyrosinemia type one and given treatment before they die. If more effective testing methods could be developed then this number could be drastically increased. The Center for Disease Control and Prevention is investigating the screening methods that are used to identify the disease; they are specifically focusing on the metabolite succinylacetone. The researchers compared and evaluated the newborn screening methods of different laboratories that measured succinylacetone in dried blood spot samples to detect asymptomatic tyrosinemia type I. Pre-prepared and pre-determined samples were given to the labs to analyze along with a questionnaire. Surprisingly the labs each reported back large differences in the amount of succinylacetone they found in the blood. The wide range of concentrations and inability to repeat in laboratory setting emphasized the need to “harmonize quantitative results among laboratories” according to the CDC. Dried blood spot matrix calibers are used to analyze the blood results, currently there are no preparation standards for the calibers so this would be the first step in fixing the problem. The CDC will continue to investigate this topic to insure a more effective and universal method is developed in order to catch this disease in its early stages.After doing some more research on the disease this study left me feeling worried. Treatment is essential to prevent death of the children and while no other articles I found suggested that the testing methods were ineffective I think that this study speaks for itself.