104 



J. LEJEUNE 



clone with a quite small Ph^ chromosome; 2 (Riiffie and Lejeune, 1962) 

 exhibiting a clone of 45 with the loss of one of the small acrocentrics. 



Table I 



Author 



Number of Number of cases 

 cases with Ph^ 



Remarks on negatives 

 cases 



Nowell and Hungerford, 1961 



Tough et al., 1961 



Ohno et al, 1961 

 Fitzgerald, 1962 



Taken together we have the actual correlation: 



This simple comparison excludes a chance effect and leads to the hypothesis 

 that the same acrocentric is involved in all cases, namely the 21. It must be 

 emphasized that this identification agrees with the microscopic observations 

 and also with the abnormality of the nuclei of granulocytes known in mongols 



since 1947 (Turpin and Bernyer). 



A very simple conclusion drawn from these data could be as follows: there 

 are on chromosome 21 genes or blocks of genes which normally depress the 

 granulocytic series. Triplication of these increases the reactivity of the 

 lymphatic series, and conversely, loss of them permits abnormal growth of 

 the granulocytic series. 



Those reflections are, for the moment, purely theoretical, and the number 

 of observations on which they are based is much too small. Nevertheless, it can 

 reasonably be hoped that in the near future, accumulation of data will 

 allow a judgment on the role of chromosomal aberrations m the production of 

 human leukaemias. 



