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Letter to the Editor: Response to Richard Dowson’s letter to the editor published in the May 18th/2022 edition

A letter to the editor from Leon Retief
Letter to the Editor MJT1
Letter to the Editor

I had intended my previous letter about multiple sclerosis to be my last on the subject, however, Mr. Richard Dowson’s letter of 14 May (published online at contains yet more statements which should not slip by without a response.

A risk factor is anything which increases the chance of someone contracting a disease. In the case of MS these risk factors include, among others, low vitamin D levels, Epstein-Barr virus and genetic susceptibility.

Nobody that I know of has attempted to show that any of the above factors are by themselves the sole, actual cause of MS, but all have been shown to play a role in its etiology – i.e., every factor is necessary but not sufficient, in the same way that a motorcar by itself is necessary for a motor vehicle accident, but not sufficient - other factors also have to come into play.

Mr. Dowson contradicts himself considerably: on the one hand we read “Funded studies examined Vitamin D as the cause of MS…” and that no link has ever been confirmed. On the other hand, “… it is just another ‘risk factor’. “

It has long ago been shown to not to be a cause of MS and nothing in the present literature asserts this. Nevertheless, it is undeniably a risk factor.

One cannot have your cake and eat it, too. If it is a risk factor then there is a link. This has been shown in many research papers and also in six links I gave in my previous letter. Perhaps Mr. Dowson overlooked them. 

Mr. Dowson also writes: “After a 7-year Review of MS Literature, I found no valid research proving a genetic link to MS.”

Perhaps Mr. Dowson should take a closer look. The literature teems with good research about the contribution of genes to the development of MS. Although MS is known not to be a genetic disease, the contribution of genes to this disease cannot be denied. The first mention of a link between genes and MS that I know of dates from 1997, see links 1 - 6 and in particular 7, where one can read the following: “The role of genetic contribution to MS emerged from both twin and familial clustering studies…” 

“Monozygotic or identical twins were shown to exhibit significantly higher clinical concordance rate (25%–30%) than dizygotic or fraternal twins (3%–7%)… “

“The lifetime risk of MS in first-degree relatives of MS index cases is estimated at 3% (4% for siblings, 2% for parents, 2% for children), or threefold greater than the age-adjusted risk for second-degree and third-degree relatives (1%) and 10- to 30-fold greater than the age-adjusted risk in the general population (0.1%–0.3%)…”

“… the risk of half-siblings is lower than that of full siblings, whereas the risk for step-siblings of MS index cases and for individuals adopted by families with MS are similar to the general population. Thus, the familial recurrence risk of MS increases in proportion to the amount of genetic sharing with the affected family member but not in a linear relationship. A meta-analysis of more than 500 studies reported a recurrence risk for monozygotic twins of 18.2% and 2.7% for siblings, and a sibling relative risk (λs) of 16.8…”

Lastly, neither Alzheimer’s disease nor Parkinsonism are, according to Mr. Dowson, “explained away” as purely or even predominantly genetic disease, but elaborating on this completely wrong statement falls outside the scope of this letter.

I am reminded of Richard Feynman’s famous aphorism: The first principle is that you must not fool yourself, and you are the easiest person to fool.

Concentrating on a single agent as the cause of a multifaceted disease like MS is a sure way to fool yourself.


Leon Retief   

The views and opinions expressed in this article are those of the author, and do not necessarily reflect the position of this publication.