Occurrence of human leukocyte antigen B51-related ankylosing spondylitis in a family: Two case reports

Figure 1 Radiographic images of the father (case 1) and the daughter (case 2) with ankylosing spondylitis. A: Sacroiliac joint of the father showing complete ankyloses; B: Lumbar spine imaging of the father in the shape of “bamboo spine”; C: Computed tomography image of the sacroiliac joint of the daughter showing multiple definite erosions with sclerotic changes on both sacroiliac joints; D: Magnetic resonance image of the lumbar spine of the daughter revealing fat deposition at the corners of the lumbar spine, probably due to ankylosing spondylitis.

Figure 2 Computed tomography image of the sacroiliac joint(s) of the two daughters who tested positive for human leukocyte antigen B51. A, B: Multiple small undulating lesions are apparent on both sacroiliac joints, suggesting grade 1 bilateral sacroiliitis were seen in one daughter; C, D: Small undulating lesions in both sacroiliac joints are apparent, suggesting grade 1 bilateral sacroiliitis in the other daughter. The lesions are indicated by the red circle.

Figure 3 Pedigree of the family. Human leukocyte antigen B51:01 carriers had either ankylosing spondylitis (black arrow) or grade 1 sacroiliitis. HLA: Human leukocyte antigen.