New pill to treat genetic diseases  

Thursday, May 03, 2007

A recent article in the Times Online talks about a pill that treats genetic disease. The pill, called PTC124, targets genetic mutations that are caused by a faulty transcription from a normal codon to a stop codon, causing the protein chain to end abnormally.

Orac has a very interesting article up explaining the science behind the discovery in more detail.

Basically, this drug works against what are called nonsense mutations. DNA provides the information necessary to produce proteins. It is made up of individual building blocks called nucleotides, while protein is made up of individual building blocks known as amino acids. The way that the genetic code in DNA is translated into proteins, which form enzymes, structural proteins, and proteins that carry out virtually every function necessary for life, is through large protein complexes called ribosomes. Ribosomes "read" the DNA, whose code is based on three-nucleotide sequences called codons, each of which codes for a different amino acid. Given four nucleotides and triplets, there are 64 possible codon combinations for 20 amino acids, which means that the genetic code is "degenerate"; i.e., most amino acids are coded for by more than one codon. There is a set of three codons, however, that do not code for any amino acid. They are known as stop codons, because when the ribosome encounters them it interprets it as a signal that the protein chain should end. When a mutation causes a codon to change from a normal codon that codes for an amino acid to a stop codon, it is known as a nonsense mutation, and it results in the termination of the protein chain wherever the mutation occurs.

The pill contains a compound that allows the faulty stop codon to be ignored during transcription, reversing the effect. PTC124 is still in clinical trials and set to finish a Phase II study soon. So far the results show minimal side effects and haven't shown that normal stop codons are ignored, only the nonsense mutations. It's still too early to say how safe or effective it will be in practice, but so far it looks promising.

I didn't think in my lifetime I'd see medical advances so promising in treating genetic diseases, and I certainly didn't think it would be a pill. It's exciting to see the results that a better understanding of our world are yielding.

(via Orac)

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