**Question:** All are true regarding Anklosing spondylitis except -

A. Ankylosing spondylitis (AS) is a chronic inflammatory disorder primarily affecting the axial skeleton and associated with HLA-B27 antigen.
B. It primarily affects the appendicular skeleton.
C. It is characterized by the absence of inflammation on X-rays.
D. It has a higher incidence in individuals with a family history of AS.

**Correct Answer:** **Option B:** Ankylosing spondylitis primarily affects the axial skeleton, including the spine, sacroiliac joints, and the ligaments connecting the vertebrae. The disease manifests itself as inflammation and pain in the spine, making it difficult for the patient to flex and move. Although it is associated with HLA-B27 antigen, AS does not exclusively affect the appendicular skeleton.

**Option C:** Ankylosing spondylitis is characterized by the presence of inflammation on X-rays, which is generally observed in the form of sacroiliitis and syndesmophytes. The misconception arises from the assumption that AS does not cause spinal deformation, which is not true.

**Option D:** Ankylosing spondylitis is associated with a family history of AS, which increases the risk of developing the condition. However, it is not exclusively affected by having a family history of the disease. This option suggests that AS exclusively affects individuals without a family history of the disease, which is incorrect.

**Option A:** Ankylosing spondylitis is characterized by inflammation and pain in the axial skeleton, as mentioned earlier. The misconception addressed in this option is the primary focus of AS affecting the appendicular skeleton.