Here are my thoughts:
1. MS is a disease that affects a specific portion of the CNS, namely the myelin sheath (white matter) as well as the axons (gray matter).
2. Neurons are spared in MS. If MS was simply a matter of the immune system indiscriminately causing damage to the central nervous system, it seems neurons would be affected more. You would see more symptoms in people that have similar characteristics of Alzheimers which is a disease that only effects neurons (loss of memory of self, friends, family, etc).
Alzheimer’s disease results in extensive damage to the gray matter of the brain, which is basically a buildup of proteins in the brain in the form of “plaques” and “tangles,” which are associated with dying or injured neurons.
3. MS has a specific pattern of disease, hence the EDSS score which looks specifically at these defects:
■ pyramidal - weakness or difficulty moving limbs
■ cerebellar - ataxia, loss of coordination or tremor
■ brainstem - problems with speech, swallowing and nystagmus
■ sensory - numbness or loss of sensations
■ bowel and bladder function
■ visual function
■ cerebral (or mental) functions
4. There is a huge amount of evidence that shows MS is a disease that has genetic as well as environmental components. If MS was strictly genetic (like CCSVI or a metabolic disorder as described above), it would be seen in 100% in identical twins (same DNA). But the reality is that one twin is only 30% as likely to acquire MS if the other twin has MS.
5. The phenotype of MS will not always be the same. Here is a good article on this:http://www.direct-ms.org/pdf/ImmunologyMS/Frohman%20Mechanisms.pdf
It is also important to recognize that the aggregate contribution of germline genetic variants to the disease course of a given patient with MS may be modest. This is highlighted by observations that the clinical expression of MS may be very different even between monozygotic twin siblings who both have the disease. It is therefore likely that several postgermline events influence the clinical expression of MS.