All of the following has HLAB27 associated with uveitis except –
**Core Concept**
HLA-B27 is a major histocompatibility complex (MHC) class I molecule associated with various autoimmune and inflammatory conditions. In the context of uveitis, HLA-B27 is linked to specific forms of the disease, especially in the presence of other clinical features.
**Why the Correct Answer is Right**
HLA-B27 is strongly associated with acute anterior uveitis (AAU), particularly when accompanied by ankylosing spondylitis (AS) or reactive arthritis. This association is thought to be due to the molecular mimicry between HLA-B27 and other proteins, leading to an immune response against self-antigens. The HLA-B27 molecule is also implicated in the pathogenesis of posterior uveitis and panuveitis in the setting of AS.
**Why Each Wrong Option is Incorrect**
**Option A:** While HLA-B27 is not the primary association, it can be seen in some cases of intermediate uveitis, particularly in patients with pars planitis. However, this is not the primary association.
**Option B:** HLA-B27 is indeed associated with Behçet's disease, which can manifest with uveitis. Behçet's disease is a form of vasculitis that involves multiple organ systems, including the eyes.
**Option C:** HLA-B27 is also linked to sarcoidosis, a granulomatous disease that can cause uveitis. Sarcoidosis often presents with bilateral hilar lymphadenopathy on chest radiographs.
**Clinical Pearl / High-Yield Fact**
Remember that HLA-B27 is a useful marker for diagnosing ankylosing spondylitis and other spondyloarthropathies in the presence of uveitis. However, its absence does not rule out these conditions, as many patients with AS or reactive arthritis may not have HLA-B27.
**Correct Answer: D.**