Paula,

To answer your earliest question on entire genome; I think this geneticist suggests exactly what you mean:

Currently, a screen of all known PD genes using conventional methods (sequencing and gene-dosage studies) is at least as expensive as sequencing the entire exome of an individual, which can be conducted for as little as US$5,000, with prices continuing to fall. Nevertheless, the key element for any meaningful study of the role of genetic factors in PD will remain the collection of a demographically and clinically well-characterized patient sample, such as the one described by Alcalay and colleagues.

For the full argument in support of genetic screening for early onset people (they are impacted more).

http://www.nature.com/nrneurol/journ....2010.197.html

Is this along the line of what you were thinking?

Laura