Disturbances to this tightly orchestrated process are responsible for features of diseases such as osteoporosis and rheumatoid arthritis, which show excessive bone breakdown, or ankylosing spondylitis, where abnormal bone growth occurs.

Barber explained that he lives with a rare, debilitating and “dangerous” form of arthritis called ankylosing spondylitis, which prevents him from sitting in or rising from low chairs.

The Rev. William Barber II said he needs the chair because he suffers from ankylosing spondylitis, a disabling bone disease.

Barber has a condition called ankylosing spondylitis, and walks slowly with the aid of a cane.

For example, an early Humira patent, which expired in 2016, claimed that the drug could treat a condition known as ankylosing spondylitis, a type of arthritis that causes inflammation in the joints, among other diseases.