Bio-Tech: The Genetics of Aging
The Genetics of Aging
Genetic surgery may be used to deal with aging. Among other factors that cause an organism to age, there are at least two distinct genetic causes.
DNA Damage
DNA can be damaged by radiation, chemicals, or errors introduced during replication. Cells contain mechanisms to detect and repair this damage, but over time the errors occur faster than they can be fixed. Eventually, the DNA can become so damaged that it no longer functions properly. Cells that inherit such DNA become senescent (unable to divide), and eventually die without producing new cells. If the senescence mechanism breaks, the cells grow into a cancer. Degradation of DNA in the mitochondria is also suspected to be a significant cause of aging effects.
Gene therapy could be used to improve the correction of these errors, postponing cell death and some of the effects of old age.
Telomere Length
Telomeres are repetitive DNA sequences up to 20,000 base pairs long on the ends of chromosomes. They serve as caps to prevent the loss of genetic data during DNA replication, and are necessary because every time a DNA strand is copied, the DNA polymerase reaction stops a few hundred bases before reaching the ends. Without telomeres to pad the protein-encoding bases, meaningful data would be lost.
Over time, the telomere chain shortens, and may eventually vanish. At this point, the cell detects DNA damage and becomes senescent. Since it cannot repair this damage, it will eventually undergo apoptosis. As an organism grows older, more and more cells throughout its body suffer this fate, organs begin to fail at an increasing rate, and the organism eventually succumbs to age.
Preventing or reversing the loss of telomeres is likely to be an important part of staving off the effects of old age. This could be achieved with genetic surgery or proteus viruses, to regulate the enzyme telomerase in adult cells. Telomerase exists naturally in gametes, and acts there to extend the telomere chain, ensuring offspring inherit DNA with sufficient telomeres to live a full life. In adult cells, it needs to be produced and then controlled carefully to avoid producing immortal cancerous cells!