8 A NEW TYPE OF BRACHYPHALANGY IN MAN. 



II. REVIEW OF LITERATURE. 



After the rediscovery of Mendel's work it was not long until evidence 

 was presented to the effect that several human characters are inherited 

 in a way consistent with the Mendelian laws. Among the clearest 

 cases are, as is well known, several malformations affecting the hands 

 and feet, such as adactyly, monodactyly, hypodactyly, syndactyly, 

 and Polydactyly; hypophalangy, brachyphalangy, hyperphalangy, and 

 ankylosis of phalanges, separately or in different combinations. They 

 all behave as dominant characters; and as the standard case, Far- 

 abee's fundamental investigation of a brachyphalangous (by him 

 described as hypophalangous) family will retain its merited place in 

 the text-books dealing with this subject. 



In the following pages consideration will be given only to brachy- 

 phalangy and combinations in which brachyphalangy is the main 

 feature. Brachyphalangy is defined as a shortening of definite pha- 

 langes along their long axis, while other phalanges are normal. Scat- 

 tered around in the literature, a great many cases are reported which 

 belong to this group of malformations. When we take into considera- 

 tion the mechanism of the growth in length of the phalanges (the undis- 

 turbed growth during the growth years of the epiphysial cartilages 

 which continuously yields material for the ossification process) it is at 

 once clear that many different influences which interfere with this 

 mechanism will result in a shortening of the phalanx in question. A 

 trauma (or different pathological processes, such as inflammations, 

 etc., which destroy the epiphysial cartilages) will result in a cessation 

 in the growth in length of the bone, and disturbances in the normal 

 embryological development may lead to the same result. 



Several cases belonging to these types of brachyphalangy are easily 

 excluded from the material because they have no bearing upon our 

 subject, but some may present a pathological-anatomical picture 

 which is Ukely to be confused with the ones we are here considering. 

 This is especially true of some of the cases of brachyphalangy called 

 forth by embryological disturbances. One group deserves special 

 mention, as presenting features of interest for our purpose. 



This type is rather commonly met with in the literature. It is 

 characterized by a total absence or marked shortening of all the 

 phalanges of the second row on one hand, combined with a defect of 

 the musculus pectoralis major and minor and eventually of some other 

 breast muscles on the same side. Furst (1900) gives 12 cases from the 

 literature, all very Uke each other in appearance. The interesting 

 point is that this brachyphalangy, which is not inherited and is recog- 

 nized as belonging to the embryological malformations, invariably 

 affects the second row of phalanges. 



When the cases previously mentioned are excluded, those cases of 

 brachyphalangy remain in which we have more or less information, 



