Clinical genetics / edited by Arnold Sorsby.

Date:
1953
Catalogue details

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

Credit: Clinical genetics / edited by Arnold Sorsby. Source: Wellcome Collection.

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    DISEASES OF THE SKIN may undergo sarcomatous metaplasia, but this is uncommon and probably occurs in less than 5 per cent of cases. The pigmentation varies in intensity, is patchy, and may occur independently of the subcutaneous tumours. The disease is essentially benign but disfiguring. Fig. 118.—Multiple neurofibromatosis. {By courtesy of St. Thomas's Hospital, London.) Fig. 119.—Neurofibromatosis showing local¬ ized tumours on the forearm. {By courtesy of St. John's Hospital and the Institute of Dermatology, London.) A Fig. 120.—Pedigree of multiple neurofibro¬ matosis; III/I died of fibrocarcoma with metastases. Heredity.—There is a tendency for affected members of the same family to show more or less similar chnical pictures, although different famihes may vary some¬ what in the degree of tumour formation or of pigmentation, and in the situation of deeper neurofibromas. Cockayne describes over 100 famihes in which neuro¬ fibromatosis was inherited as a strictly dominant character. Nearly all the pedigrees described by the numerous authors on the subject indicate the presence of a single dominant gene with a high degree of penetrance and variable degree of expression (Fig. 120). This may be partly explained, however, by the fact that pigmentation or deep-seated tumours have passed unnoticed; and, of course, not all the family is usually examined by a critical physician. It is possible that a modifying gene may influence the pathogenic gene, as in epiloia. Certainly the clinical picture is definite and circumscribed but it must be remembered that not all the features of the disease are necessarily present in every patient. Whether the dominant pedigrees of bilateral acoustic neurofibromas, which have been reported in absence of other signs of von Recklinghausen's disease, are due to the same gene is not so certain. Several authors have suggested that adenoma sebaceum and multiple neurofibromatosis are part of one disease, but clinical and genetical evidence against this seems to be overwhelming. 232