50 



A NEW TYPE OF BEACHYPHALANGY IN MAN. 



Table 1. — Numerical ratio between affected and normal individuals in the offspring of 



heterozygous individuals. 



This ratio, 23 normals to 26 brachyphalangous individuals, is strik- 

 ingly in accord with the expectation 1 :1. But it is necessary to keep 

 in mind the source of error introduced by the fact that in generations 

 II and III we have information about only the B !-type individuals. 

 It is impossible to tell if some of the fanaily members here characterized 

 as "normals" in reality were brachyphalangous of the B type. 



It is worth mentioning that there is a tradition in the family, as 

 we have heard several times, that every second child of a brachy- 

 phalangous family will have the malformation and that the oldest 

 one always is affected. The germ of truth in this tradition is that half 

 of the children are Ukely to be brachyphalangous, but the slightest 

 attention shows that the family's belief in alternative repetition is 

 not in accord with the facts.^ 



We have in our material one case interpreted as a marriage between 

 two individuals heterozygous for brachyphalangy, namely, the mar- 

 riage between 11.5 cf C. A. B. H. and his cousin 17.1 9F.G.0.(p. 26). 

 The expectation is in such a case that one out of four children should 

 be normal, while two should be heterozygous and one homozygous for 

 brachyphalangy. The family resulting from this marriage, family 

 3 of the IV generation, comprises 2 individuals; one of those is shown 

 to have been heterozygous for brachyphalangy. The reasons support- 

 ing the supposition that the other was homozygous for the factor are 

 discussed above (pp. 44-46). 



1 After this chapter had been written we noticed, curiously enough, that Farabee met exactly 

 a similar tradition in the family studied by him: "The family tradition is that every other child 

 bom of a short-fingered parent has short fingers" (1905). 



