298 ALBERT EHRENFRIED 



group inherited from the father, and 56 per cent of the females from the 

 mother. 



It was found that if the father was affected 52.4 per cent of the offspring 

 had the disease, while if the mother was affected 41.4 per cent of the chil- 

 dren were affected. 



It has long been recognized that the disease may be transmitted by an 

 unaffected female. Stocks found that about 5 per cent of all cases seem to 

 inherit through an unaffected mother, and that about 25 per cent of females 

 who transmit show no evidence of the affection. But these unaffected 

 mothers transmit with the same intensity and in the same proportion of off- 

 spring as those affected. No case has been recorded of an unaffected male 

 transmitting the disease. 



A study of the grandparents in relation to the parents yields interesting 

 data. It has been found that when the father and his father are affected, 

 63.4 per cent of the children are affected; father and his mother give 45.7 

 per cent; mother and her mother 43.8 per cent; and mother and her father 

 give 37.5 per cent. Thus two successive generations of males give by far 

 the highest percentage of occurrence. 



Insofar as the affected male is known to transmit to a higher percentage 

 of his offspring than the affected female, it will be seen that in successive 

 male transmissions this effect will be cumulative. But this tendency may 

 be offset in some measure by the observation that a considerable percentage 

 of affected males are likely to remain single. 



On the other hand, Stocks records 9 instances of an affected person marry- 

 ing twice— 6 males and 3 females. There was a total of 43 children. In 

 the first marriages 60 per cent of the offspring were affected, and in the second 

 marriages 77 per cent. 



Consanguinity has not appeared as an important factor in the condition, — 

 having been noted in only five families in this series. The affection is re- 

 ported as having been found once in a pair of twins. 



In summary, I have stated the opinion that scientific medicine in its 

 recent developments has taken but little cognizance of the tremendous force 

 of hereditary factors in the origin and occurrence of disease. 



That if the data available in medical literature on the subject of disorders 

 determined by germ plasm were organized and classified, it would lead to a 

 clearer understanding of the subject, and a better appreciation of the in- 

 fluences of heredity upon human life and health. 



That hereditary deforming chondrodysplasia, which I have briefly de- 

 scribed, clinically, pathologically, and genetically, is a well-defined disease 



