186 



CELLS, TISSUES, AND ORGANISMS 



Study of the chromosomes of somatic cells of a number of human 

 patients has revealed an astonishingly large number of disease condi- 

 tions to be due to chromosomal aneuploidy. Thus diseases such as 

 mongolism ( Lejeune, Turpin, and Gautier, 1959 ) , gonadal dysgenesis 

 (Ford, 1959; Tjio, Puck, and Robinson, 1959). and Klinefelter's syn- 

 drome (Jacobs and Strong, 1959) are now, for the first time, under- 

 standable in terms of their underlying cellular defects, all of these 

 representing conditions of aneuploidy due to possession of an excess 

 or deficiency of a single, specific chromosome in each case. The mech- 





ii I 





\ 





8 9 10 11 12 



A A 

 f, A A 



13 14 15 



y 



Figure 3. Idiogram of normal human male chromosomes. 



