The aorta later becomes fibrotic, with lumen narrowed
patchily in multiple areas. Familial cases have been reported from a number of countries, including among twins. Human Leucocyte Antigen (HLA) gene analyses have found increased frequency of HLA B52, B39.2, D12 and A24 among Japanese. The gene may lie between the MIC gene and HLA B locus on chromosome 6. HLA B52 patients may have more severe inflammation while those with HLA B39 may have more renal artery involvement. The illness ranges Pexidartinib from being asymptomatic to a catastrophic illness. It often presents in the 2nd or 3rd decade of life. It may begin with a non-specific inflammatory “pre-pulseless” phase characterised by fever, night sweats, lethargy, loss of weight, find more pains in the muscles and joints and even a mild anaemia. The erythrocyte sedimentation rate (ESR) tends to be elevated. With progression of the inflammation, vascular stenoses, usually bilateral, occur with resulting development of collateral circulation. Notably, not all patients go through these various stages. Clinical features are shown in Table 1. Others include neurological involvement leading to transient ischemic attacks or stroke, giddiness, headache or rarely seizures, while cardiac features
include congestive cardiac failure. The 1990 American College of Rheumatology criteria require 3 or 6 features of age of onset ≤40 years, limb claudication, reduced pulsation in at least 1 brachial artery, a >10 mmHg difference in systolic blood pressure between the arms, bruits audible over the subclavian artery or abdominal aorta, and abnormalities on arteriography of the aorta or its principal branches. Japanese patient are mostly female, while Indian patients
are more male. Japanese patients tend to have reduced upper limb pulses due to involvement of the ascending aorta and aortic arch, while those of Indian, Thai, Korean and Chinese origin tend to have renovascular hypertension due to abdominal aorta and renal artery involvement. The gold standard for clinical diagnosis is arteriography. The International Conference on Takayasu Arteritis in 1994 classified the disease based on the angiogram (Table 2). Histology is conceivably the most diagnostic. In view of the invasive nature of angiography and impracticality of biopsy, ultrasonography is now very widely used to make the diagnosis in a clinically suspected patient. Ultrasound reveals thickened vessel walls (macaroni sign), including the carotid artery. Magnetic resonance angiography may reveal a better understanding of wall edema, and inflammation if contrast is used. These may be used to monitor response to treatment. Steroids remain the cornerstone of medical therapy. While early studies showed poor benefit, later studies have shown better response rates of about 50%, with reduction of symptoms of inflammation and even return of pulses in some patients.