Matt Ridley on some recent discoveries in genetics and medicine that may help to explain certain diseases like multiple sclerosis:
The virus implicated in multiple sclerosis is called HERV-Fc1, a bizarre beast called an “endogenous” retrovirus. What this means is that its genes are part of the human genome. For millions of years, they have been integrated into our own DNA and passed on by normal heredity. It was one of the shocks of genomic science to find that the human genome contains more retroviral than “human” genes: some 5% to 8% of the entire genome.
Normally, the genes of endogenous retroviruses remain dormant, but — a bit like a computer virus that springs into action on a trigger — something wakes them up sometimes, and actual viruses are made from them, which then infect other cells in the body. The Danish scientists suggest that this is what happens in multiple sclerosis. Bjørn Nexø of Aarhus University writes that “retroviral infections often develop into running battles between the immune system and virus, with the virus mutating repeatedly to avoid the immune system, and the immune system repeatedly catching up. One can see the episodic nature of multiple sclerosis as such a running battle.”
The possibility that you can inherit the genes of a virus blurs the distinction between a genetic and an infectious disease. The HERV-Fc1 genes lie on the X chromosome. Since women have twice as many X chromosomes as men, this might explain why some forms of MS are more common in women. Dr. Nexø concludes hopefully: “The finding that a disease is caused by an infectious agent is an encouraging one. These are the diseases which we know best how to treat.
The research also appears to show a link between cat ownership and schizophrenia:
Human beings can also catch toxoplasma from cats, and it’s known to affect behavior: altering personalities, slowing reaction times and increasing the risk of car accidents. More than 20 studies have now found an association between schizophrenia and toxoplasma. Schizophrenia is more common among those who had pet cats in their childhood homes (but not in those who had pet dogs).
Indeed, some scientists think that schizophrenia only became common, around 1870, when keeping cats as indoor pets became fashionable. The parasite has genes for dopamine, a neurochemical found in excess in schizophrenics.
