Hereditary malformations of the extremities of various types in human beings have been described in the literature under such terms as syndactylism, polydactylism, brachydactylism, ectrodactylism, macrodactylism, hyperphalangism and hypophalangism. Other malformations of the extremities reported to be hereditary are such conditions as fragilitas osseum, cartilaginous exostosis and clubfoot. There is a vast literature replete with case reports and family histories of various inherited conditions.
Among constitutional anomalies that are inherited may be mentioned such conditions as deaf-mutism, chronic hereditary trophodermia, harelip and cleft palate, congenital cataract and dwarfism, color blindness and hemophilia. A broader conception of inheritances of systemic faults is found in Sir Archibald Garrod's "Inborn Errors of Metabolism,"1 in which one finds a fine discussion of such faults in body chemistry as albinism, alkaptonuria, cystinuria, hematoporphyria congenita and pentosuria.
Harvey Cushing2 wrote an excellent monograph on symphallangism, in which there is absence or fusion of certain