Antall József szerk.: Orvostörténeti közlemények 87-88. (Budapest, 1979)

TANULMÁNYOK - Czeizel, Endre: A heredodegeneraciós tan történeti értékelése (angol nyelven)

2. "// is wrong to regard only those cases as familial or hereditary affection where the clinical picture occurred in several members of the family, for single cases may also be observed, for even in the most affected families may occur exceptions." (Only those who are familiar with human genetics can really appreciate the depth of this statement, for that is why the genealogical table of patients suffering from the same disease are nowadays analysed together [Weinberg's proband method]. Jendrassik also realized that an exact evaluation of heredity could be hoped solely in the knowledge of the fate of all the gametes.) 3. "Heredity as aetiology is specific: it develops such clinical pictures that would not come to life for any other reason. Independent occurrence of symptoms that do not occur by themselves in other diseases or unusual, odd joining of symptoms that would not occur together in other cases, generally develop on a hereditary basis." (Hereditary affections, due to the pleiotropy of the gene mostly form really characteristic syndromes.) 4. "Hereditary diseases do not appear in typical, well-definable clinical pictures, but the variation of symptoms occurs in infinite series in the most heterogeneous circle. Although the respective types may be used in practice, they should not be conceived of as distinct diseases". (Though this statement cannot be accepted any more, his way of putting it is understandable considering clinical knowledge of the time.) 5. "Any tissue of the organism may be affected by hereditary defects, the nervous system as well as the musculature, the connective tissue, the bones, the individual organs, etc." (All this has been proved since then beyond doubt.) 6. "Unusually grouped symptoms of slow advance most probably correspond to inherited degeneration." (This is really characteristic of most of the clinical pictures of neuropathology.) 7. "Close relationship of the parents increases the possibility of heredodegeneration"

. In 13 cases of this sort out of 21 the parents were in close relationship. Jendrassik's explanation is also very clear: the marriage of relatives "accentuates more sharply" the manifestation of genetic load. He mentions as an example the case of a patient born from a brother-sister relation, (he has several such cases in his material) who had only 512 ancestors in 10 ascending generations instead of the usual 1024. (Clinical pictures due to latent recessive genes and polygenic systems are more probable to occur in the children of blood relatives.) Essentially, Jendrassik wanted to achieve two aims of fundamental importance. First: to separate from the heap of neurological diseases the genetically defined ones, i. e. those different from external affections in their origin, clinical appearance and development. This is a great merit of his, since it is along this path that the distinction of exogenous and hereditary neurological diseases became conscious and took a start. Second: he aimed at unifying all genetically defined clinical pictures of neurology into a uniform pathological unit, the so-called heredodegeneration. This view could not stand the flow of time, but his endeavour, especially when considering the date of his activity, is understandable. It is a matter of numerous and fortunately rare clinical pictures. (Such a disease falls on one person out of 10 000, 100 000, maybe 1 million.) Besides, their clinical appearance varies very much. That is why even today, in the possession of uncomparably more developed diagnostical devices, 11 Orvostörténeti