Syndromology: an updated conceptual overview. VIII. Deformations and disruptions.

A deformation is an abnormal form or position of the body caused by nondisruptive mechanical forces. Clubfoot, congenital hip dislocation, and infantile mandibular asymmetry (not based on mandibular malformation) serve as examples. The musculoskeletal system is involved in almost all deformations. Various disturbances of intrauterine movement are the usual causes and commonly occur during the fetal period. Causes may be mechanical or malformational. The former includes first pregnancies, small maternal size, uterine malformations and tumors, and amnionic rupture leading to oligohydramnios. Malformational causes usually involve the urogenital system and the central nervous system. A disruption is a morphologic defect of an organ, part of an organ, or a larger region of the body resulting from a breakdown of, or interference with, an originally normal developmental process. Amnionic band disruptions with digital amputations serve as an example. The most recent studies of disruptions and their suggested mechanisms are discussed. Finally, the interrelationships between malformations, deformations, and disruptions are explained.