Antall József szerk.: Orvostörténeti közlemények 87-88. (Budapest, 1979)
TANULMÁNYOK - Czeizel, Endre: A heredodegeneraciós tan történeti értékelése (angol nyelven)
it is often a problem to recognize or differentiate some of the hereditary diseases of the nervous and muscular systems. But the level of genetic knowledge then can be judged as most essential. Jendrassik's communications on heredodegeneration appeared between 1896 and 1902. Mendel, or Mendelian law respectively was not "discovered" until 1900, so the genetic differential diagnosis of hereditary clinical pictures of the nervous and muscular systems due to the affections of the allels of the respective loci, the proof of their nosological specificity could take place only after. Jendrassik, unfortunately, did not take up this task, although he knew Mendel's work. (In 1911, he makes a digression to introduce the "ingenious" Mendel's laws when he discourses upon the majority of male infants at birth. He even makes an interesting experiment to harmonize Mendelian and Galtonian laws.) He sums up once more the doctrine of heredodegeneration in a study in German entitled "Die hereditären Krankheiten" published in the "Handbuch der Neurologie" edited by Lewandowsky in 1911. This study established the world fame of Jendrassik and the doctrine of heredodegeneration. In this monography he touched upon Mendel's activity, too, and even tries to evaluate his own observations in its light. Thus he gives a new bio-genetical classification, as follows. There are "1. latent hereditary forms, i.e. in which the parents are apparently normal and the process spreads over later to several generations. Here belong also the cases where the hereditary manifestation jumps over one or two generations; 2. forms with consanguinity of the parents, this is especially evident in spastic paralysis, retinitis pigmentosa, deaf-mutism, etc; 3. forms of bilateral hereditary diseases where the affection may be latent recessive, e. g. albinism. It is probable that the two latter forms are fundamentally identical; at last 4. sexually differential forms, that means healthy females and affected males; the offspring of affected —male are healthy, the male offspring of healthy —female are affected." Actually, points 1—3 describe autosomal recessive, and point 4 X-linked recessive inheritance. The autosomal dominant mode of inheritance is probably left out here because the evident "perpendicular" heredity had been many a times treated in the literature, in his own works, too. The fact is, however, that he does not try to compare Mendelian law with the familial of the respective diseases of heredodegeneration and to analyse them in his patients. Although this could have certainly made of him —knowing the extent of his patient material and his abilities —an establisher of clinical genetics. But in the last decade of his life he rather dealt with questions of natural philosophy, with the mechanism and localisation of thinking and other intellectual activities, with the problems of physical energy and also with music theory. The nosological distinction of heredodegenerative diseases has taken long decades and still has not ended. Presently, nearly 20 monolocus types of spastic paraplegia and nearly 50 of spinocerebellar ataxia are known. Thus, as it is put by P. E. Becker, one of the greatest authorities of neurological genetics in 1971: "...// is not surprising that Jendrassik in 1911 included a considerable number of heterogeneous hereditary diseases of the nervous system with the uniform designation «heredodegeneration» in the Handbook of Neurology." "The term «heredogeneration» is still evident in the
