More Than Human Embracing The Promise Of Biological Enhancement

CHAPTER 1 Choosing Our Bodies In 1989, Raj and Van DeSilva were desperate. Their daughter Ashanti, just four, was dying. She was born with a crippled immune system, a consequence of a problem in her genes. Every human being has around thirty thousand genes. In fact, we have two copies of each of those genes--one inherited from our mother, the other from our father. Our genes tell our cells what proteins to make, and when. Each protein is a tiny molecular machine. Every cell in your body is built out of millions of these little machines, working together in precise ways. Proteins break down food, ferry energy to the right places, and form scaffoldings that maintain cell health and structure. Some proteins synthesize messenger molecules to pass signals in the brain, and other proteins form receptors to receive those signals. Even the machines inside each of your cells that build new proteinscalled ribosomesare themselves made up of other proteins. Ashanti DeSilva inherited two broken copies of the gene that contains the instructions for manufacturing a protein called adenoside deaminase (ADA). If she had had just one broken copy, she would have been fine. The other copy of the gene would have made up the difference. With two broken copies, her body didn't have the right instructions to manufacture ADA at all. ADA plays a crucial role in our resistance to disease. Without it, special white blood cells called T cells die off. Without T cells, ADA-deficient children are wide open to the attacks of viruses and bacteria. These children have what's called severe combined immune deficiency (SCID) disorder, more commonly known as bubble boy disease. To a person with a weak immune system, the outside world is threatening. Everyone you touch, share a glass with, or share the same air with is a potential source of dangerous pathogens. Lacking the ability to defend herself, Ashanti was largely confined to her home. The standard treatment for ADA deficiency is frequent injections of PEG-ADA, a synthetic form of the ADA enzyme. PEG-ADA can mean the difference between life and death for an ADA-deficient child. Unfortunately, although it usually produces a rapid improvement when first used, children tend to respond less and less to the drug each time they receive a dose. Ashanti DeSilva started receiving PEG-ADA injections at the age of two, and initially she responded well. Her T-cell count rose sharply and she developed some resistance to disease. But by the age of four, she was slipping away, no longer responding strongly to her injections. If she was to live, she'd need something more than PEG-ADA. The only other option at the time, a bone-marrow transplant, was ruled out by the lack of matching donors. In early 1990, while Ashanti's parents were searching frantically for help, French Anderson, a geneticist at the National Institutes of Health, was seeking permission to perform the first gene-therapy trials on humans. Anderson, an intense fifth-degree blackbelt in tae kwon do and respected researcher in the field of genetics, wanted to show that he could treat genetic diseases caused by faulty copies of genes by inserting new, working copies of the same gene. Scientists had already shown that it was possible to insert new genes into plants and animals. Genetic engineering got its start in 1972, when geneticists Stanley Cohen and Herbert Boyer first met at a scientific conference in Hawaii on plasmids, small circular loops of extra chromosomal DNA in which bacteria carry their genes. Cohen, then a professor at Stanford, had been working on ways to insert new plasmids into bacteria. Researchers in Boyer's lab at the University of California in San Francisco had recently discovered restriction enzymes, molecular tools that could be used to slice and dice DNA at specific points. Over hot pastramiNaam, Ramez is the author of 'More Than Human Embracing The Promise Of Biological Enhancement', published 2005 under ISBN 9780767918435 and ISBN 0767918436.