Which of the following is an example of a disruption anomaly in fetal development?

• A. Congenital amputations caused by amniotic bands
• B. Down syndrome
• C. Spina bifida
• D. Cleft lip due to teratogenic exposure

Answer: (A)

Disruption anomalies occur when an external, destructive process interrupts tissue that was already formed during development. Amniotic bands can wrap around a developing limb and constrict blood flow, leading to tissue loss or amputation. The limb’s cells were forming normally, but the external band caused disruption, resulting in an abnormal outcome.

In contrast, the other scenarios stem from issues intrinsic to development or from teratogenic effects. A genetic alteration like an extra chromosome leads to a malformation from the start. Failure of neural tube closure is a malformation arising from improper early development. Cleft lip caused by teratogenic exposure is also a malformation due to faulty development from an external agent, not a later external disruption of tissue that had already formed.