As mentioned in my previous post, cystic fibrosis is a genetically linked disorder. The condition is inherited in an autosomal recessive pattern, which means that in order to inherit the disease, two mutated copies of the gene must be present (in contrast to autosomal dominant disorders, in which only a single copy of the mutant gene is required to result in the disease – see Huntington's disease for an example) . If only one mutated copy is inherited, then the person is unaffected, but becomes a carrier. If two carriers have children together, then there is a one in four chance of each child having the disease. This can possibly be described better with a diagram (taken from the CF Trust website):
The mutation in question occurs in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The CFTR gene is found on Chromosome 7, is 230,000 base pairs long and encodes a protein which is 1,480 amino acids long. There are over 1,500 mutations which can occur to cause the disorder – the most common being ∆F508, which occurs in around two-thirds of CF cases (66-70%) worldwide. The ∆F508 mutation results in abnormal folding of the protein it encodes - an ion channel – leading to its rapid degradation. Rapid degradation of CFTR, along with other protein faults caused by alternative mutations, result in the symptoms of CF due to the loss functioning CFTR. In my next science post, I will explore how CFTR works normally, and how abnormally functioning CFTR in CF sufferers causes the symptoms associated with the disorder.
Also, it's Cystic Fibrosis Week! Check out the link for fundraising events and related good things.
And a brief training update - I've increased my running now to 5 min run/1 min walk over 23 mins, which is going ok, but unfortunately I've got a bit of a thigh strain. Hopefully it'll get better soon!
