What does the term 'sequence' refer to in congenital malformations?

The term 'sequence' in the context of congenital malformations specifically refers to a chain reaction where one symptom or phenotype leads to another symptom or phenotype, thereby cascading through a series of developmental anomalies. An illustrative example of this is the Potter sequence, where renal agenesis leads to oligohydramnios, which then causes facial deformities and limb deformations due to limited amniotic fluid. This terminological nuance emphasizes the idea that one primary defect can initiate a series of secondary defects as a part of a developmental sequence, illustrating the interconnectedness of anatomical development and the potential for one abnormality to influence the manifestation of others.