Hereditary defect of cobalamin metabolism with adolescence onset resembling multiple sclerosis: 41-year follow up in two cases

New Epidermal-Growth-Factor-Related Insights Into the Pathogenesis of Multiple Sclerosis: Is It Also Epistemology?

Recent findings showing that epidermal growth factor (EGF) is significantly decreased in the cerebrospinal fluid (CSF) and spinal cord (SC) of living or deceased multiple sclerosis (MS) patients, and that its repeated administration to rodents with chemically- or virally-induced demyelination of the central nervous system (CNS) or experimental allergic encephalomyelitis (EAE) prevents demyelination and inflammatory reactions in the CNS, have led to a critical reassessment of the MS pathogenesis, partly because EGF is considered to have little or no role in immunology. EGF is the only myelinotrophic factor that has been tested in the CSF and spinal cord of MS patients, and it has been shown there is a good correspondence between liquid and tissue levels. This review: (a) briefly summarises the positive EGF effects on neural stem cells, oligodendrocyte cell lineage, and astrocytes in order to explain, at least in part, the biological basis of the myelin loss and remyelination failure in MS; and (b) after a short analysis of the evolution of the principle of cause-effect in the history of Western philosophy, highlights the lack of any experimental immune-, toxin-, or virus-mediated model that precisely reproduces the histopathological features and “clinical” symptoms of MS, thus underlining the inapplicability of Claude Bernard's crucial sequence of “observation, hypothesis, and hypothesis testing.” This is followed by a discussion of most of the putative non-immunologically-linked points of MS pathogenesis (abnormalities in myelinotrophic factor CSF levels, oligodendrocytes (ODCs), astrocytes, extracellular matrix, and epigenetics) on the basis of Popper's falsification principle, and the suggestion that autoimmunity and phologosis reactions (surely the most devasting consequences of the disease) are probably the last links in a chain of events that trigger the reactions. As it is likely that there is a lack of other myelinotrophic growth factors because myelinogenesis is controlled by various CNS and extra-CNS growth factors and other molecules within and outside ODCs, further studies are needed to investigate the role of non-immunological molecules at the time of the onset of the disease. In the words of Galilei, the human mind should be prepared to understand what nature has created.

Multiple sclerosis and intracellular cobalamin defect (MMACHC/PRDX1) comorbidity in a young male

Background

Methylmalonic acidaemia with homocystinuria type C (cblC defect) is an inherited error of cobalamin metabolism. Cobalamin deficient processing results in high levels of methylmalonic acid and homocysteine. The latter is considered to be a risk factor for multiple sclerosis (MS). We report on the first case of a patient with comorbid cblC defect and MS.

Case report

This young male presented at the age of 14 with a relapsing-remitting neurological disorder associated with imaging alterations suggestive of MS. Treatment resulted in a partial clinical improvement with vanishing of white matter lesions. Later on, the emergence of unexpected clinical features led to a metabolic work-up, revealing a cobalamin intracellular defect. Genetic analysis disclosed a single variant in MMACHC (c.482G > A; p.Arg161Gln) and another splicing variant in PRDX1 (c.1-515G > T) that cause the silencing of the wild-type MMACHC allele, so confirming the diagnosis of cblC defect. Although cblC treatment was effective, when 17-year-old he experienced a relapse of neurological symptoms. Further imaging and laboratory studies eventually supported the diagnosis of MS.

Discussion

While the comorbid association of MS and cblC in our patient may remain anecdotic, we suggest measuring Hcy and MMA levels in young patients with a relapsing-remitting demyelinating disorder, in order not to miss a cblC defect, that requires a specific and effective treatment.