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DNA Protein Conclusion Phenylketonuria by Zamaan Qureshi and Chinmay Amin Intro: Phenylketonuria (PKU) is rare genetic disorder which causes an amino acid, phenylalanine to build up in the body. PKU is caused by an issue in the enzyme that helps to break down phenylalanine. The first cases were identified in 1934 when Dr. Asbjørn Følling examined two severely mentally retarded children. He proved that PKU was responsible for this by noticing phenylpyruvic in their urine. Phenylketonuria was the first inborn issue that impacted the mind. Onset of this disease is usually from birth two 2 years old. In extreme rare cases, the disease doesn’t appear late into adulthood. In one case, the disease wasn’t noticed until the patient was 59 years old. Symptoms “include intellectual disability (formerly called mental retardation), delayed development, behavioral, emotional and social problems, psychiatric disorders, neurological problems that may include seizures, hyperactivity, poor bone strength, skin rashes (eczema), a musty odor in the child's breath, skin or urine, caused by too much phenylalanine in the body, fair skin and blue eyes, because phenylalanine cannot transform into melanin — the pigment responsible for hair and skin tone, and an abnormally small head (microcephaly)” (Mayo Clinic). Prognosis http://medifitbiologicals.com/phenylketonuria/ Within the first 1-2 days of birth, doctors can test for Phenylketonuria by taking the blood of the heel of the baby. for the long term is normal unless there are issues with therapy or if blood phenylalanine levels rise. Normal life expectancy if no issues occur. Location: Chromosome 12 (12q) 12q23.2 Protein: Phenylalanine Hydroxylase (PAH) is an enzyme for breaking down a part of an amino acid called phenylalanine. Interestingly, phenylalanine is found in all proteins humans consume and some artificial sweeteners. On top of this, Phenylalanine Hydroxylase converts phenylalanine into tyrosine, which our bodies use to make different variations of hormones, chemical signals that go to the brain, and a physical feature called melanin which is a pigment. This is what colors our skin and hair. Beyond this, if tyrosine s broken down further, it can be used to produce ATP. Approximately 500 mutations have been found in the PAH gene, all of these people have PKU. Generally, the mutations that occur are only single amino acid changes, however, there are a variation of deletions that have been identified. A rare kind of mutation in the PAH gene sees that the actual production of PAH enzyme is incorrect. When these variations of mutations occur, the processing of phenylalanine is disturbed. Due to this, phenylalanine builds up in the blood and tissues, and because of what tyrosine does to help our brain signals, and because the nerve cells are extremely sensitive, the phenylalanine builds up and shuts down brain signals. When untreated, the disease leads to severe brain damage. Other names of the enzyme Phenylalanine Hydroxylase include… • L-Phenylalanine,tetrahydrobiopterin:oxygen oxidoreductase (4-hydroxylating) • PH4H_HUMAN • Phenylalaninase • Phenylalanine 4-Hydroxylase • Phenylalanine 4-Monooxygenase • PKU1 http://drustapbio.wikia.com/wiki/Phenylketonuria This image describes some of the physical features of patients with Phenylketonuria who are mentally retarded vs normal children. Inheritance: Autosomal Recessive https://ghr.nlm.nih.gov/gene/PAH http://omim.org/entry/612349 Examples of PKU in Patients 1) Mecca, Saudi Arabia (1988) In the year 1998, in Mecca, Saudi Arabia, there was a case of PKU involving an ethnically Malay boy (Initials H.A.R. - no full name given) born through a fairly normal pregnancy. However, he showed signs of being abnormal (not being able to hold his head up for 3 months, or sit without support for 20 months). He also experienced changing of hair color, and signs of standard retardation later in his youth. Many tests did not show any conventional abnormalities, but through a chromatography test of his urine, it was discovered that there was excess Phenylalanine. He, like many others with PKU, was put on a low Phenylalanine diet to prevent clotting and further retardation. http://www.e-mjm.org/1989/v44n3/phenylketonuria.pdf PKU Diet PKU Patients require a specific, low protein diet, because these foods create high blood PHE levels and the liver of people with PKU are not able to break down the acid PHE. Based on research, PKU patients should have to follow this diet for the rest of their life in order to ensure that they are fine even when PHE levels are low. www.nursebuff.com https://depts.washington.edu/pku/about/diet.html PKU Video- https://www.youtube.com/watch?v=XKSoMi4U-1k “Living with PKU with Kevin Alexander”