What is DPD Deficiency?
DPD Deficiency (Dihydropyrimidine dehydrogenase deficiency) is an autosomal recessive metabolic disorder in which there is absent or significantly decreased activity of dihydropyrimidine dehydrogenase, an enzyme involved in the metabolism of uracil and thymine.
There are two ways of knowing you have DPD Deficiency. In some people with severe DPD Deficiency, the disorder becomes apparent as an infant. They will show neurological problems such as recurrent seizures (epilepsy), intellectual disability, small head size (microcephaly), increased muscle tone (hypertonia), delayed development of motor skills such as walking, and autistic behaviors that affect communication and social interaction. Amazingly, other affected individuals are asymptomatic. They do not have any signs or symptoms of the condition. Individuals with asymptomatic DPD Deficiency may be identified only by laboratory testing.
How does DPD Deficiency relate to chemotherapy?
DPD is also needed to break down the chemotherapy drugs 5-FU (fluorouracil) and capecitabine. Without the DPD enzyme in your body, undergoing 5-FU based chemotherapy can be a serious risk. Roughly 4-8% of the population has some form of DPD Deficiency, ranging from partial deficiency to complete lack of the enzyme in their system. In Kerrie’s case, she unknowingly has a total deficiency.
Patients with full or partial DPD Deficiency are at serious risk of neuroencephalopathy (brain damage) and death.
A potential sign of DPD Deficiency is consistently having high levels of thymine or uracil in your blood, since the enzyme needed to process these is absent from your body. This could be the first indication that there is a potential risk for DPD Deficiency and further blood tests before chemotherapy could prevent severe 5-FU toxicity.
At the moment, people treated with 5-FU (fluorouracil) or capecitabine do not have routine testing for DPD Deficiency before their treatment. Up to 30% of cancer patients receiving 5-FU experience severe toxicity (grades 3 and 4).
Get tested BEFORE you start treatment
If you are to receive 5-FU (fluorouracil) or capecitabine as part of your chemotherapy treatment you should insist your doctor arrange a test PRIOR to beginning treatment. Hopefully you are not are reading this after having severe side effects from your treatment.
Pre-testing for DPD Deficiency is HIGHLY recommended before treatment with 5-FU (fluorouracil). MedScape talks about testing facilities on their website.
Learn more about DPD Deficiency at www.dpd-deficiency.com.
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