HLA-B51 is strongly associated with<unk> <unk>  is considered more prevalent in the areas surrounding the old silk trading routes in the Middle East and in Central Asia. Thus, it is sometimes known as Silk Road<unk> . However, this<unk>  is not restricted to people from these regions. A large number of serological studies show a linkage between the<unk>  and HLA-B51. HLA-B51 is more frequently found from the Middle East to South Eastern Siberia, but the incidence of B51 in some studies was 3 fold higher than the normal population. However, B51 tends not to be found in<unk>  when a certain SUMO4 gene variant is involved, and symptoms appear to be milder when HLA-B27 is present. At the current time, a similar infectious origin has not yet been confirmed that leads to<unk> , but certain strains of S. sanguinis has been found to have a homologous antigenicity. Vasculitis resulting in occlusion of the vessels supplying the optic nerve may be the cause of acute optic neuropathy and progressive optic atrophy in<unk> . Histological evaluation in a reported case of acute optic neuropathy demonstrated substitution of the axonal portion of the optic nerve with fibrous astrocytes without retinal changes. CNS involvement in<unk>  may lead to intracranial hypertension most commonly due to dural venous sinus thrombosis and subsequent secondary optic atrophy.
Behçet's disease
Stevens–Johnson syndrome
Chilaiditi syndrome
Reactive arthritis
Coats' disease
Febrile neutrophilic dermatosis
Sever's disease
Lhermitte's sign