A structural malformation of the feet, commonly called clubfoot, is known as:

The term "clubfoot" refers specifically to a structural malformation of the foot that is medically recognized as talipes. This condition usually involves the foot being twisted out of shape or position. Talipes can vary in severity and may affect one or both feet, and it is often noticeable at birth.

In the context of the other options, hemochromatosis is a genetic condition that causes the body to absorb too much iron, while Klinefelter's syndrome and Turner’s syndrome are chromosomal disorders that affect sexual development and other physical characteristics, but none of these relate to the physical structure of the feet. Therefore, identifying talipes as the correct term for clubfoot clarifies the specific medical terminology used in relation to this foot deformity.