The etiology of VACTERL association: Current knowledge and hypotheses.

VACTERL association is a condition involving the presence of multiple congenital anomalies. The condition was first described more than four decades ago, and is not extremely rare. However, relatively little is understood about the causes and underlying biology of the condition as a whole. There are many reasons for this, but there is increasing recognition that VACTERL is extremely clinically as well as etiologically heterogeneous, and this heterogeneity--as well as other hypothesized factors--have caused challenges to identifying the causes for a substantial proportion of patients. Current knowledge about the causes of this condition (or group of conditions) are described, followed by a discussion of possibilities that may reveal more answers for patients as well as researchers and clinicians who work related to this disorder.