Chapter 9: Disease (Genome)

•The ABO blood group gene is located on chromosome 9.

• This gene determines a person’s ABO blood type.

• Blood groups have been used in court cases to help identify murderers and in paternity suits.

• The ABO blood group system was first discovered in 1900 by Karl Landsteiner.

• Type O blood is known as the universal donor because people with this type can donate to anybody safely.

• In the 1920s, the genetics of the ABO blood groups were explained and in 1990, the gene involved was discovered to be galactosyl transferase enzyme recipe (1,062 letters long).

•The difference between the A gene and the B gene is seven letters out of 1,062.

• People with type A blood have the letters C, G, C, G.

• People with type B blood have the letters G, A ,A ,C .

• There are other rare differences.

• The O group has just a single spelling change compared with A. In people with type O blood, the 258th letter is missing altogether which causes a reading-shift or frame-shift mutation.

•The link between disease and mutations was first noticed in the late 1940s by an Oxford graduate student with a Kenyan background, Anthony Allison.

• The haemoglobin gene, where the sickle-cell mutation occurs as just a single-letter change, is not alone in this respect. According to one scientist, it is the tip of an iceberg of genetic resistance to malaria.

• Up to twelve different genes may vary in their ability to confer resistance to malaria. Nor is malaria alone. At least two genes vary in their ability tuberculosis, including the gene for the vitamin D receptor, which is also associated with a variability in susceptibility osteoporosis.

• A newly discovered but similar connection links the genetic disease cystic fibrosis with the infectious disease typhoid.

•The genome is a record of our pathological past, and the prevalence of O blood groups in native Americans may reflect the fact that cholera and other forms of diarrhoea never established themselves in the newly populated continents before relatively modern times.

• A better explanation is needed for the puzzling prevalence of the O version of the gene in native Americans, especially given that ancient pre-Columbian mummies from North America often seem to have A or B type blood.

• One possible explanation is syphilis, which seems to be indigenous to the Americas. People with O type blood seem to be less susceptible than those with other types.

•The genome is constantly changing, and what we know now is only a snapshot of what it will be in the future.

• J.B.S Haldane, Suresh Jayakar, Robert May, and William Hamilton are all scientists who have contributed to the understanding of how dynamic the genome truly is.

• There is no such thing as a definitive edition of the genome because it is always changing.

"A gilded No is more satisfactory than a dry yes" - Gracian