Volume 15

Treasury of human inheritance / edited by Karl Pearson, R.A. Fisher, L.S. Penrose.

Date:
1909-
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Treasury of human inheritance / edited by Karl Pearson, R.A. Fisher, L.S. Penrose. Source: Wellcome Collection.

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    common in dystrophia myotonica. Thus I find it difficult to know how to classify Boeters’s pedigrees, hut reproduce them here in case some other worker may succeed in solving the problem they present. With regard to dystrophia myotonica we have been fortunate in being given access to the material collected by Otto Maas over a period of years. This material covers 300 definite cases of the affection in 91 pedigrees; only those cases in which Maas found definite signs of myotonia are classified as affected individuals on our pedigree plates, but it is important to note that Maas regarded many other individuals, often all members of the pedigree, as showing suspicious or incipient signs of disease; he included slight hollows in the temporal regions, weakness in blowing out the cheeks, slight wasting in the lateral part of the thenar eminences, a suspicion of myotonia on tapping the thenar musculature, and an early loss of hair as signs of incipient affection when the individual concerned was known to be a member of a family exhibiting dystrophia myotonica. We have not felt able to accept these criteria as signs of disease merely because they occur in members of affected stocks, but have noted in the description of pedigree plates such signs as Maas observed and regarded as suspicious or indicative of incipient affection. It is a testimony to Dr Maas’s generosity that he should have thus allowed me to interpret his observations in a sense with which he is not in agreement; I do so in no dogmatic spirit, fully aware that Maas has a wider experience in detecting all grades of this affection than perhaps any other neurologist, but taking the standpoint that so far as is possible only ascertained facts, and not suspicions, should be introduced into pedigrees. The great and unique value of Maas’s material lies in having this mass of observations made by a single neurologist who carried out a routine examination of every member of the families, often repeatedly over a term of years, and spared himself no trouble in the pursuit of individuals to perhaps considerable distances. Maas takes the view that Thomsen’s disease and dystrophia myotonica are inherently the same disease; thus he, like Boeters, includes all his cases under the one category. It is clear that the relative rarity of pedigrees of Thomsen’s disease ensures for the most part that Maas’s material may be regarded as homogeneous; this very fact, however, must raise doubts of the homogeneity of Boeters’s series of pedigrees, particularly so when we recall that Thomsen in his long fife never met a case resembling his own outside his family, and Birt, working in Canada, never saw another case of the disease. Maas obtained his material by following up and investigating the families of patients with the disease attending a neurological hospital, primarily the National Hospital, Queen Square; also in a few cases by examining patients with cataract at an ophthalmological hospital; in other respects his material is quite unselected. Perhaps he would be unlikely to find the rare cases of Thomsen’s disease in such fields; certainly they would not be expected in an ophthalmological hospital amongst patients with cataract, and, indeed, a patient suffering from a not very disabling disease, which appears early in fife and affects many members of consecutive generations, probably adapts himself to the conditions he has learned to expect and tends to seek no aid from a neurological or other hospital. A further sample of pedigrees of dystrophia myotonica has been collected from the literature. These include 89 pedigrees with 349 affected individuals, of whom a few belong to pedigrees not appearing on the plates. It is valuable to have these two contributing samples of histories of the condition, bearing in mind that in series A, collected by Maas, all members of families were examined when possible, including many individuals who thought themselves normal but in whom the investigator detected signs of affection; thus when the age of onset of the disease is stated it is likely to be earlier when judged by the age at which signs of affection were demonstrable than in the series B, recorded by other observers, who state the age at which the patient first became aware of symptoms. Another source of divergence between the two series lies in the fact that many cases of series B are recorded by ophthalmologists who met the source of the pedigree through the associated cataract; thus some accentuation of this association may be expected in series B. Finally, Maas investigated the family history in every case to which he obtained access, whereas in published pedigrees there is always a selection in favour of the histories including multiple cases of the disease.