Genre: News package
Duration: 2 minutes 33 seconds
This is a brief (two and a half minute) news piece about a patient “S” , who suffers from Phenylketonuria (PKU) and the successful application by his parents for treatment using the drug Kuvan.
PKU is a well-characterised autosomal recessive inborn error of metabolism in which the body cannot appropriately process the amino acid phenylalanine (Phe) dues to mutation in the gene for the enzyme Phenylalanine hydroxylase (PAH), whose role is to convert phenylalanine to tyrosine. Because the genetic basis of PKU is well characterised, it features regularly in introductory courses on biochemistry and/or genetics.
Kuvan, also known as sapropterin, is a pharmaceutical version of tetrahydrobiopterin or BH4, which is an essential cofactor for PAH. Taking Kuvan is essentially increasing the concentration of BH4 in the body and thus promoting the activity of naturally occurring PAH to process more Phe to Try. Since the action of PAH is the rate-limiting step in the degradation of excess phenylalanine, increasing this reaction makes a significant contribution to lowering the concentration of Phe. However, this is not a complete solution, and patients with PKU are sometimes recommended to have a low phenylalanine diet, even if they are on the drug.
This clip could be used in a module teaching about the genetics and biochemistry of PKU. It is also an example of healthcare rationing, the complexities of deciding which medicines should be provided by the NHS. Decisions on the cost effectiveness of drugs is often made by the NICE, the National Institute for Health and Care Excellence (the name evolved, the acronym didn’t!) On this occasion, however, the decision was made by the High Court. Kuvan cost £100 per day, and the hospital treating S had argued it was not warranted on grounds of clinical efficacy. The high court disagreed, stating that the effectiveness of the drug was well established (eg. in this 2007 article from The Lancet).
Background on PKU can be found via this link (same article as liked above)
Some background to the case of S can be found via this link.