Subject: Genes environment etc

From: [email-masked] (Howard Wright)
Date: 16 Sep 1996 23:57:58 GMT

I recently heard an interesting radio interview on the ABC (Australian
Broadcasting Corporation) Heath Report that set me thinking. The
interview was actually about juvenile onset diabetes, not MS, but it
occurred to me that the ideas being discussed may be relevant to MS.
Like MS, juvenile onset diabetes is believed to be an autoimmune disease
where the immune system attacks the islet cells in the pancreas.  The
distribution of juvenile onset diabetes has some things in common with
MS.  For example, incomplete penetration in identical twins, and an
increasing incidence with increasing latitude away from the equator.

The interviewee, Professor Kevin Lafferty, Director of the John Curtin
School of Medical Research in Canberra, suggested that juvenile onset
diabetes depends on a genetic factor and an environmental factor such as
a virus or a bacteria.	But, rather than being a cause of the disease,
the environmental factor prevented the disease in genetically
susceptible individuals.  His theory is based on a study of mice bred to
be genetically susceptible to diabetes.  He has suggested that possibly
an infection somehow primes the immune system in such a way as to
prevent the attack on the islet cells.

Is it possible that the as yet unidentified environmental factor
involved in MS works the same way?  Is it possible that those of us who
have MS have the susceptibility to MS built in to our genes, and also
somehow missed out on exposure to a common childhood infection rather
than being exposed to some exotic bug?	This could possibly explain the
lower prevalence of MS in tropical climates and also the apparently
increasing incidence of MS in recent years.

Does anyone have any thoughts to offer?

The full transcript of the talk is available on the web at
http://www.abc.net.au/rn/talks/8.30/helthrpt/hstories/hr090996.htm