Abstract
Historically, ankylosing spondylitis (AS) was thought to be more common in males than in females. However, recent research into AS epidemiology has revealed an increasing incidence of female patients. First, 24-year-old patient A sought medical attention for severe pain in her lower back and buttocks. Then, 4 years later, patient B, 22 years old, the younger sibling of patient A, sought medical attention for the same symptoms. Both patients were diagnosed with AS. We note that the older sister’s diagnosis was delayed by 5 years for a number of reasons, including the gender-specific nature of the disease. At the same time, the younger sister was diagnosed with AS immediately because the older sister had already been diagnosed. This case highlights the gender differences in the AS diagnosis. Despite the traditional understanding of the disease as predominantly affecting males, clinicians should consider and highlight the increasing prevalence of AS in females to avoid misdiagnosis.