Ghost In Your Genes
Genetic inheritance was thought to have involve the transmission of DNA from one generation to the next affected by occasional mutations in the DNA itself. They found out that the human genome was less complex and had less genes then even less complex organisms such as plants. The human genome, only containing about 30,000 genes, now lead scientists to believe that other factors allow genes to be switched on and off in response to the environment. Professor Pembrey was drawn to two genetic diseases due to families exhibiting unconventional genetic inheritance patterns. The two diseases were Angelman syndrome, which displays clinical symptoms of jerky movements, little or no speech and a very happy personality, and Prader-Willi syndrome, in which patients are found to be very floppy in infancy and develop an insatiable appetite associated with obesity in later life. He found out that these two diseases were caused by the same genetic alteration. There was a small deletion on chromosome 15. The parent from whom the mutation was inherited determined which disease the patient would get. If it was inherited from the mother the child would have Angelman syndrome and if it was inherited from the father the child would have Prader-Willi syndrome. This suggested that the chromosome knew its origin and must had been tagged or imprinted in some way. This was known as genomic imprinting. During sperm and egg production(meiosis), a chemical change results in the same DNA sequence on each chromosome having different functional properties. These events can lead to a particular gene being turned on or off. This is what epigenetics is based of. Professor Reik noticed that when a mouse embryo was placed in a culture dish some of genes would be switched off and wondered whether this could also be true for human embryos during in vitro fertilization or IVF. Using the disease, Beckwith-Wiedeman syndrome, Reik discovered that Beckwith-Wiedeman syndrome...
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