Why not syndrome and why association?
VATER or VACTERL is not a syndrome as there is a no single pathological cause responsible for the common incidence.
Components of VACTERL are
V - Vertebral anomalies
occur in 80 t0 85% cases - hemivertebrae or hypoplastic vertebrae
A - Anal atresia or imperforate anus
occur in 50-55% cases
C - cardiac malformations
occur in 75% cases
VSD, ASD and ToF are common
TE - tracheoesophageal fistula with esophageal atresia
occur in 70% cases
renal anomalies occur in 50% cases like agenesis or dysgenesis, single umbilical artery can also occur
Radial anomalies like radial aplasia, hypoplastic thumbs can occur. Syndactyly, polydactyly can also occur.