Jan, one of the differential dx for MS is adult-onset autosomal dominant leukodystrophy.

"An autosomal-dominant leukodystrophy presenting in adulthood, causing motor and cerebellar deficits, usually with prominent autonomic dysfunction. The genetic defect is unknown.

Especially resembles primary progressive MS, with chronic upper motor neuron and cerebellar deficits accompanied by confluent white-matter lesions on MRI and occasionally IgG abnormalities in the CSF.

Family history with autosomaldominant inheritance. Automatic involvement is also prominent early."

http://www.neurology.wisc.edu/public...bs/Neuro_2.pdf
(see #56, at the end of the document).

I think there are different kinds of leukodystrophies too:

http://www.ninds.nih.gov/disorders/l...odystrophy.htm

Cherie