Complex sentence: The most typical disorder induced by thalidomide were reductional deformities of the long bones of the extremities (phocomelia), otherwise a rare deformity, which therefore helped to recognise the teratogenic effect of the new drug.
Split into simpler sentences: The most typical disorder induced by thalidomide were reductional deformities of the long bones of the extremities. Phocomelia otherwise a rare deformity, which therefore helped to recognise the teratogenic effect of the new drug.