Genetical factors in the aetiology of multiple sclerosis

Decreased erythrocyte glutathione peroxidase activity in multiple sclerosis

The mean activity of glutathione peroxidase (GSH-PX) in erythrocytes of 22 Israel-Jewish patients with multiple sclerosis (19.3 +/- 4.5 U/gHb) was significantly lower than in a control group of 30 Jewish patients with various neurological disorders (24.3 +/- 5.1 U/gHb). This observation confirms a similar finding of a decreased activity of GSH-Px in erythrocytes of multiple sclerosis patients in Denmark (Shukla et al. 1977). These results are discussed in relation to the possibility of selenium deficiency and to the recently described genetic polymorphism and ethnic variation of GSH-Px activity in human red cells. It is concluded that additional investigations are required in order to elucidate the cause of the decreased activity of this enzyme in red cells of patients with multiple sclerosis.

Multiple sclerosis: relationship between seasonal variations of relapse and age of onset

The incidence of multiple sclerosis (MS) is age-dependent being rare prior to age 10, unusual prior to age 15, with a peak in the mid 20s. The manifestation of MS, therefore, appears to be dependent upon having passed through the pubertal period suggesting an endocrine influence on the timing of onset of the disease. Since pineal melatonin secretion progressively declines from childhood to puberty and as melatonin exerts an immunomodulating influence, we have proposed that the dramatic decline in melatonin secretion just prior to the onset of the clinical manifestations of puberty may lead to disruption of immune responses resulting in either reactivation of the infective agent or in an increased susceptibility to pubertal or post-pubertal infection. Melatonin secretion undergoes annual rhythms with a zenith in winter and declines to a nadir in the spring. Thus, the fall in melatonin secretion in the spring may account for epidemiological findings revealing a high incidence of relapse of MS in the spring. If the manifestations of MS are related to the fall in melatonin secretion in the post-pubertal period, then one would expect patients with a pubertal onset of the disease to have a higher incidence of relapses in spring than in winter. To test this hypothesis, we investigated in 51 patients the relationship between the seasonal occurrence of the last MS relapse with the age of onset of first manifestation of MS. While 9 of 22 patients (40.9%) who relapsed in spring (March-May) had the onset of MS prior to age 18, only 2 of 29 patients (6.9%) who relapsed in winter (November-February) experienced the onset of first symptoms prior to the age of 18 years (p < .005). These findings thus support the hypothesis implicating the pineal gland and melatonin secretion in the timing of onset of MS. Moreover, the findings may have clinical implications with respect to the prophylaxis of MS relapse in patients who experience seasonally-dependent exacerbation of symptoms.

Multiple sclerosis: the role of puberty and the pineal gland in its pathogenesis

Epidemiological studies demonstrate that the incidence of multiple sclerosis (MS) is age-dependent being rare prior to age 10, unusual prior to age 15, with a peak in the mid 20s. It has been suggested that the manifestation of MS is dependent upon having passed through the pubertal period. In the present communication, I propose that critical changes in pineal melatonin secretion, which occur in temporal relationship to the onset of puberty, are intimately related to the timing of onset of the clinical manifestations of MS. Specifically, it is suggested that the fall in melatonin secretion during the prepubertal period, which may disrupt pineal-mediated immunomodulation, may stimulate either the reactivation of the infective agent or increase the susceptibility to infection during the pubertal period. Similarly, the rapid fall in melatonin secretion just prior to delivery may account for the frequent occurrence of relapse in MS patients during the postpartum period. In contrast, pregnancy, which is associated with high melatonin concentrations, is often accompanied by remission of symptoms. Thus, the presence of high melatonin levels may provide a protective effect, while a decline in melatonin secretion may increase the risk for the development and exacerbation of the disease. The melatonin hypothesis of MS may explain other epidemiological and clinical phenomena associated with the disease such as the low incidence of MS in the black African and American populations, the inverse correlation with sun light and geomagnetic field exposure, the occurrence of relapses in relation to seasonal changes and fluctuations in mood, and the association of MS with affective illness and malignant disease. Therapeutically, this hypothesis implies that application of bright light therapy or the use of other major synchronizers of circadian rhythms such as sleep deprivation or application of external weak magnetic fields may be beneficial in the treatment and/or prophylaxis of relapses in the disease.

Life history and bioeconomy of the house mouse

1. More is known about the western European house mouse, Mus (musculus) domesticus than any other non-human mammal. If laboratory and field information is combined, an extremely valuable understanding of the species' bioeconomy could be obtained. 2. The seven stages of mouse life-history are surveyed (up to birth, nest life, sex life, social structure, population statics and stability, senescence, and death), and the interactions between the changing phenotype and the environment are described. 3. These interactions can be used to build up a model of the opportunities and compromises which result in the fitness of individual mice. It is not yet possible to quantify such a model, but this should in principle be achievable.

Sib risk and the dizygotic twin concordance rate for multiple sclerosis

Data have been reviewed on sib risk and the dizygotic twin concordance rate in multiple sclerosis. Even when rigorous criteria are applied, the dizygotic twin concordance rate for multiple sclerosis is apparently higher (perhaps 10 times higher) than could be explained by the sib risk. In contrast, twins with Parkinson's disease have low concordance rates even when ascertainment is by informal methods. It is concluded that such methods of ascertainment are not as biased as has been suggested, and that the high concordance rates reported for multiple sclerosis are a characteristic of the disease rather than an artifact of the ascertainment. Three hypotheses are considered which might, in principle, explain this high dizygotic twin concordance rate in multiple sclerosis: 1 One is certainly false, viz, that it is due to an excessive liability of dizygotic twins to the disease. 2 It is possible that a pathogen occurs in early infancy or in pregnancy itself. 3 It seems more likely that the high concordance rate may be explained in terms of age related events or sequences of events. (If such events were pathogenic for one member of a sibship, they would be pathogenic for another only if it were a co-twin).

Essential fatty acids in the serum and cerebrospinal fluid of multiple sclerosis patients

Statistical evaluation of essential fatty acids (determined by gas chromatography) in the serum and cerebrospinal fluid of patients with definite MS and acute CCT showed marked differences as compared to healthy subjects. It was also evident that the decrease of essential fatty acids in MS patients differed from that of CCT patients. Whereas the fatty acid levels in the serum of MS patients revealed only minor differences as compared to the controls and CCT patients, MS patients did show a clear decrease, especially of linoleic and arachidonic acids, in the CSF. This difference was most pronounced in cholesterol esters in the CSF. One absorption study with safflower oil demonstrated normal enteral absorption of essential fatty acids and the ability to cross the blood-CSF barrier.

Power of the affected-sib-pair method to defect disease susceptibility loci of small effect: an application to multiple sclerosis

The distribution of marker locus identity-by-descent scores in affected sib pairs provides a powerful tool for detecting the presence of a linked non-Mendelian disease susceptibility locus. This basic approach is here extended to include a trio of sibs. A special type of sib trio consisting of two affected and one unaffected sib is investigated. It is shown that compared to affected-sib-pairs, trios with the above configuration are less efficient in detecting the presence of a linked disease susceptibility locus. When the generalized two-allele single locus model is fitted to sib pairs affected with multiple sclerosis, an estimate of the recombination fraction of 0.21 between the putative disease susceptibility locus and the HLA complex is obtained. However, this transmission model is deemed inadequate since a recombination fraction this large is inconsistent with the variety of HLA associations observed at the population level.

A goodness-of-fit test for the polygenic threshold model: application to multiple sclerosis

Recently it has been suggested that multiple sclerosis may be a multifactorial disorder. We found in British Columbia 364 families (sibship size greater than or equal to 2) in which at least on sibling was diagnosed as having "clinically definite" multiple sclerosis. The data were tested for goodness-of-fit to the multifactorial model using an analysis that considers various parameters including ascertainment probability heritability, and sex-dependent prevalence rates. The results suggest that multiple sclerosis does not fit the multifactorial model. As an alternative genetic model we propose that a major gene could be responsible for at least a portion of the cases of multiple sclerosis.

Histocompatibility determinants in Israeli Jewish patients with multiple sclerosis

The distribution of 24 HLA antigens of the A and B loci was investigated in 197 Israeli Jewish patients with multiple sclerosis (MS) from various Jewish ethnic origins including central and eastern Europe, countries bordering the Mediterranean, the Middle East and from native-born Israelis. The results were compared with the HLA antigen frequencies in a control sample of 455 unrelated individuals representing the general Jewish population. The frequency of HLA-Bw40 among all MS patients (15%) was significantly greater (P less than 0.001) than among the controls (7%). In contrast to the findings in MS patients from other populations, there was no increased frequency of A3 and B7 and Dw2 was present in only one out of 28 patients. The study showed a similar distribution of HLA-A and -B locus antigens, especially of Bw40, in Jews of diverse ethnic origins represented in the control group.

Anomalous lymphocyte-antigen reaction in relatives of multiple sclerosis patients. A study of a possible genetic factor in the disease

A combined familial study of multiple sclerosis (MS) in England and in the Rostock area of the GDR using the macrophage electrophoretic mobility (MEM)-LAD test embracing 132 relatives has revealed a closely similar pattern of distribution of "anomalous" LAD (Linoleic Acid Depression) values in relatives (77% type of reaction) to that originally reported in the British study. The anomaly in predominantly associated with females--all mothers of MS patients being affected, whilst daughters and sisters are also represented. In addition unusual full MS type of reaction (90% reduction) has been found in some children related to patients. There is clearly a genetic element in the development of MS probably mainfested in the inborn mishandling of unsaturated fatty acids suggested by Thompson; no recognizable pattern of inheritance is noticeable even within the combined material. There is evidence that the metabolic anomaly alone does not inevitably lead to MS, and the full abnormality may be present at an early age. A survey about the examinations and a selection of characteristic family trees of MS are given, illustrating the manner in which the 77% type anomaly is distributed with occasional omission of a generation.

Erythrocyte-UFA (Eufa) mobility test for multiple sclerosis: implications for pathogenesis and handling of the disease

Erythrocytes from patients with Multiple Sclerosis (MS) show a highly significant reduction in their absolute electrophoretic mobility in the presence of linoleic and arachidonic acids (LA; AA). Patients with other (destructive) neurological disease (OND) and normal subjects show an increased absolute mobility of their erythrocytes in the presence of LA and AA. About 40 per cent of blood relatives of MS patients show an intermediate type of reaction - being slowed by LA and speeded up by AA. Administration of LA (or gamma linolenate) to an MS patient for some months leads to change in the mobilities from the MS to normal type, the AA result altering first. The effect of LA and AA on the absolute mobility of RBC may thus be used as a simple laboratory test involving a long established technique and eliminating the animal and other needs of the macrophage electrophoretic mobility (MEM) test. The implications of these findings for our understanding and handling of MS are briefly discussed.

The linoleic acid depression (LAD) test for multiple sclerosis using the macrophage electrophoretic mobility (MEM) test

With the macrophage electrophoretic mobility (MEM) test of Field & Caspary, lymphocyte sensitization to thyroid antigen (F1-fraction) is demonstrable in all subjects--multiple sclerosis (MS) patients, those with other (destructive) neurological diseases (OND) and normals. The MEM-LAD test enables a further differentiation to be made in neurological patients compared ot normals: Linoleic acid inhibits the positive result by about 95 per cent in the case of MS, 58 per cent in normals and 45 per cent in OND. The high reduction appears to be a characteristic of MS. It is seen at all stages and in all forms of the disease and is not materially influenced by moderate immunosuppressive therapy. The mothers of MS patients show an intermediate result of about 78 per cent, suggesting a familial (genetic) background to the metabolic phenomenon described here; there is, however, evidence of an added exogenic factor for the development of the disease. The theoretical basis of the LAD test suggests further therapeutic trials of linoleic acid in treatment of MS.

Racial predilection in multiple sclerosis

Comparisons between the geographic distribution of multiple sclerosis and the habitats of various racial groups showed that racial factors alone could not explain the increase in prevalence of the disease with latitude. Racially similar groups living in different areas had different frequencies of multiple sclerosis. Conversely, racially different groups, living in the same area, had similar prevalence rates of multiple sclerosis. Moreover, migrants moving from one environment to another at a young age (before adolescence) appeared "to acquire" the risk of multiple sclerosis of the new environment. These observations suggest than an environmental factor independent of race influenced the risk of acquiring multiple sclerosis. Nonetheless, some genetic factors associated with race may also be implicated, for example, HL-A tissue antigens (perhaps by virtue of a common association with the immune response (Ir) gene), the Gm and Inv immunoglobulin characteristics and skin pigmentary characteristics (perhaps through interactions between pigmentation and calcium metabolism). The specific environmental factors determining risk of multiple sclerosis and the mechanism whereby the racial (genetic) factors may influence risk remain to be elucidated.

The natural history of man in Shetland

The Shetland Islands lie in the North Atlantic approximately equi-distant between Scotland, Norway and the Faroes. The earliest known colonizers came from the Mediterranean, but when the Vikings arrived (c. AD 800), there seem to have few or no human inhabitants. The descendants of the west Scandinavians who came to the islands in the early Viking movement still comprise the bulk of the human population, and form a series of isolates unique in the United Kingdom.

The paper summarizes the available information on the origins and physical characteristics of the Shetlanders. Much of this is trivial, but in the absence of any other review we have brought together what is known. The only blood group data are ABO frequencies which are similar to those on the other North Atlantic islands (Orkney, Faroe and Iceland). The best estimates of relationship are based on comparisons of non-metrical skull variant frequencies which show that the nearest relatives of the Shetlanders are the inhabitants of Jaeren in southern Norway. The same conclusion comes from independent evidence of linguistic affinities.

Shetland has the highest known prevalence of multiple sclerosis in the world, and possibly a high incidence of gastric ulceration. It also has a large number of standard Down's syndrome (trisomy-21) patients. These could be the result of the fathers' periodic absences at sea, resulting in their families being spread over a large span of years. Clearly there are interesting and possibly important morbidity and mortality factors operating in the population—which could give significant information about genetical factors in disease. Data on mental defect and psychiatric disease are also presented.