Section 16 — Human Cytogenetics 



beginning. More investigations will be done 

 with other tissues of the mongoloid child to 

 test the number of chromosomes. It may very 

 well be possible that these tissues will have a 

 mosaic character as a result of the mitotic 

 non-disjunction. 



The examination offers possibilities as to the 

 localization of particular bloodgroups on 

 particular chromosomes. The examination is not 

 yet finished and will be extended — if possible. 



If congenital dysplasias, whatever they may 

 be, be sometimes discordant in human mono- 

 zygotic twins and if there be moreover a dis- 

 congruency in the chromosome-pattern, one 

 may conclude that their origin lies in a very early 

 developmental phase. 



families of Group A and six families of Group 

 B. The parents of the mongoloid children had 

 a normal karyotype in 13 families. Some normal 

 siblings were found to have a normal karyotype 

 as well. All but one mongoloid of these thirteen 

 families has 47 chromosomes with a trisomy G m . 

 Translocation of a G m chromosome as cause of 

 familial mongolism was found in one family 

 only, where the mother and one mongoloid 

 child had 45 and 46 chromosomes respectively 

 with a 15/21 translocation. The father has a 

 normal karyotype. The other mongoloid child 

 died before the chromosomes were studied. 

 Evidence will be presented that several causes 

 may lead to familial mongolism and that 

 familial translocation is not its main cause. 



16.27. Chromosomal Mosaicism in a Mongol Child 

 with Average Intelligence. P. Giraud, R. Ber- 

 nard, A. Stahl, F. Giraud, M. Lebeuf, 

 and M. Hartung (Aix-Marseille, France). 



The authors are reporting the case of a 

 sixteen-year-old girl, with the typical features of 

 Mongol disease (Down's Syndrome). 



Her mental level is sufficient for a quite normal 

 (on the medium range) scholar activity. 



The chromosomic study (including a skin 

 biopsy) shows a mosaicim: Fifty (50) cells have 

 been counted and analyzed. Among these, eight 

 (8) cells were found as being 47 chromosomes, 

 trisomic for the 21 chromosome; the others 

 being normal, with 46 chromosomes. 



The authors are supputing about the con- 

 nections of a such mosaicism with the different 

 features of Mongolism, with particular attention 

 to the intellectual development. 



16.28. Familial Mongolism. 



(Iowa City, U.S.A.). 



Hans Zellweger 



Thirty-two families with more than one case of 

 mongolism are under investigation: 



A. In fifteen families more than one mongoloid 

 has been found in one and the same sibship 

 (4 times both twins, 9 times two siblings, 2 

 times three siblings were affected). 



B. Seventeen families were found with two to 

 six cases of mongolism in a wider kindred with 

 no single sibship (except one) having more than 

 one mongoloid. 



The average maternal age at the time of birth 

 of the affected children was 29.1 years in Group 

 A and 34.4 years in Group B. So far chromo- 

 somal analyses have been performed in eight 



16.29. An Extra Chromosome in Patients with 

 Pelger-Huet's Abnormality of Leucocytes. 



H. Siebner, F. Heni and D. Klaus (Tubingen, 

 Germany). 



In several patients of different sibships with a 

 Pelger-Huet's abnormality of the polymorphonu- 

 clear leucocytes a small extra chromosome with 

 subterminal centromere was found in cultures 

 from peripheral blood and in a higher percentage 

 in cultures from bone-marrow. Classified by its 

 size it belongs between the pair of autosomes 20 

 and 21 following the Denver-classification. 



A trisomy 21 appears to be unlikely, because 

 the leucocyte alkaline-phosphatase activity was 

 not increased in the studied patients, although 

 there is a well-known defective lobulation of 

 polymorphonuclear leucocytes in mongols. 

 Relations to the Ch^-chromosome and the 

 Philadelphia-chromosome are discussed. 



The extra chromosome may be regarded as 

 the result of a deletion with nondisjunction of a 

 larger chromosome. There is also the possibility 

 of the same mechanism which is assumed by 

 Patau about the marker chromosome of 

 Waldenstrom's Macroglobulinaemia. Chromo- 

 somes of one culture were labelled with tritiated 

 thymidine. 



16.30. Pyknotic and Binucleate Cells in Irradiated 

 Peripheral Blood Cultures. J. Weuer, Dorothy 

 L. Weuer and H. E. Duggan (Edmonton, 

 Canada). 



Irradiated peripheral blood when cultured 

 yields aberrant nuclear forms. Apart from 

 chromosome aberrations the binucleate cells 

 and the pyknotic leukocytes are also important. 



308 



