Thursday, December 2, 2010
What happens when one single enzyme in your body isnt working correctly? One would think it wouldnt be that big of a deal right? Well, in this instance that incorrect. Phenylketonuria (PKU) is a disorder that one inherits, and if left untreated, there are changes in cells inside the brain that lead to mental retardation. This disorder has been traced to a tiny mutation in a single gene on chromosome 12. The cause of PKU is when a person inherits a genetic mutation that disrupts the function of a crucial metabolic enzyme (PAH). Normally, PAH is produced in the liver, and there is helps convert an amino acid, phenylalanine into another amino acid called tyrosine. A person without a good PAH can accumulate dangerously high phenylalanine levels in the brain. With an excess of phenylalanine, it poions neurons and causes mental retardation and epilepsy if the condition is not treated. A person only gets PKU when he or she inherits two copies of the mutated gene, one from each parent. So there have to be certain symptoms right? Well in a way yes, a child with undetected PKU may have a smaller than normal head, epilepsy, and mental retardation. The excess phenylalanine in the skin creates a musty odor and a deficiency in tyrosin leads to lighter skin and hair. Most children in developed countries are screened at brith for PKU, before symptoms develop. PKU appears in about 1 in 10,000 births in Caucasians and East Asians. There are some ethnic groups that have higher rates (Turks, Irish) and some even have lower rates (Japanese). PKU is exceedingly rare in Africans. As a newborn baby, they are screened for high levels of phenylalanine in their blood. Some other blood tests must be conducted in order to determine if high levels is due to PKU or another protein-BH4-which causes the same symptoms. As one can see, by just one single enzyme in the body not working, it can cause something very hurtful and horrible to a single person or even a whole family.