Anti-Centromere B, IgG Progressive system scleroderma (PSS) is an autoimmune multi-systemic disease characterized by calcification of the skin. PSS is characterized by affection of the connective tissue and vessels of the microvasculature, leading to slowly progressive fibrosis and sclerosis at a late stage of the disease. In addition to the skin, the gastrointestinal tract is most affected in patients . In addition, the disease affects the kidneys, lungs, heart and musculature. With systemic scleroderma, the value of AT to the centromere B (ACA) and topoisomerase I ( Scl-70), as diagnostic indicators of limited and diffuse systemic scleroderma, respectively. ACA recognizes more than 6 centromeric nucleoproteins. For scleroderma, the sensitivity is 19-33%; specificity is 90-99.9%. The definition of ACA is useful for predicting limited skin lesions (sensitivity - 44%, specificity 79-93%) and low probability of development of X-ray signs of pulmonary fibrosis (sensitivity - 12%, specificity 71%). CREST-syndrome - This is a variant of PSS, with a slower flow. The prognosis is much more favorable, compared with patients with PSS. The acronym CREST is composed of the first letters of the five most important clinical manifestations: Calcinosis, Raynaud's phenomenon, esophageal involvement, sclerodactyly, teleangiectasia. In patients with CREST-syndrome , circulating autoantibodies to the centromeric protein B can be detected. Determination of the anti-centromereB autoantibody has prognostic significance in the diagnosis of the Raynaud phenomenon. The phenomenon of Raynaud is often found as the first symptom of scleroderma, which precedes the remaining manifestations for several years. Antibodies to centromere B can be detected in patients with primary biliary cirrhosis (PBC). PBC and CREST-syndrome often occur together. Anti-centromere B antibodies are detected in approximately 10-20% of patients with PBC, preferably identifying patients with the Reino phenomenon and sclerodactyly. Among other centromeric proteins (for example, CENP-A (19 kDa), CENPC (140 kDa)), centromeric protein B (80 kDa) refers to the protein complex of the chromosome kinetochore, a structure that secures the attachment of spindle filaments during cell division. For the CREST-syndrome, the sensitivity of the ACA is 60-65%; specificity - 83-99,9%.