A population study of the VACTERL association: evidence for its etiologic heterogeneity.

Using the population-based data from the Metropolitan Atlanta Congenital Defects Program, the interrelation of the six defects that are components of the VACTERL association were investigated. There were 400 cases with two or more of these defects, whereas only 29 cases would be expected if the defects had occurred together randomly. There were 76 cases with three or more defects, whereas less than one case was expected. Of these 76 cases, seven had recognized causes (five chromosomal anomalies, two single-gene disorders); another 19 had recognized clinical phenotypes or syndromes of unknown etiology. In the remaining 50 cases, ventricular septal defect was the most common cardiovascular defect (30.0%), and renal agenesis was the most common renal anomaly (30%). Their most common limb defects were reduction deformities (34%) and polydactyly (20%). This study confirms the clinically recognized nonrandom occurrence of the VACTERL association. It also shows that the association is a spectrum of various combinations of its components, which can be a manifestation of several recognized disorders, rather than a distinct anatomic or etiologic entity. A common denominator of the VACTERL association is suggested to be a defective mesodermal development during embryogenesis, due to a variety of causes and leading to overlapping manifestations.