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Test Category: Immunology

Investigation Name:Myositis antibodies Immunoblot

Alias or Abbreviation:Myositis

Intro:

Indication: Dermato- and polymyositis, idiopathic myositis, anti-synthetase syndrome and overlapping syndromes. Inflammatory Myopathies Further information: Profile includes the following antigens: Mi-2α, Mi-2β, TIF1γ, MDA5, NXP2, SAE1, Ku, PM-Scl100, PM-Scl75, Jo-1, SRP, PL-7, PL-12, EJ, OJ, Ro-52 Mi-2 antibodies are typically found in patients with steroid responsive dermatomyositis. TIF-gamma antibodies may be observed patients with cancer associated myopathy, particularly dermatomyositis. MDA5 antibodies can be detected in 13-26% of dermatomyositis cases. They are highly specific for amyopathic dermatomyositis or dermatomyositis with interstitial lung disease. NXP2 antibodies may be associated with juvenile polymyositis and dermatomyositis. In adults the disease may be carcinoma associated (breast, uterine or pancreatic carcinoma). SAE1 antibodies are markers for dermatomyositis and for dermatomyositis associated with interstitial lung disease. PM-Scl75 and PM-Scl100 antibodies are found in 50-70% of patients with the polymyositis/scleroderma overlap syndrome. Ku antibodies are seen in a variety of diseases including systemic lupus erythematosus, mixed connective tissue disease, scleroderma and the polymyositis/scleroderma overlap syndrome. They are also seen in patients with pulmonary hypertension. Jo-1 (Histidyl tRNA synthetase) antibodies are found in 20-40% of patients with aggressive polymyositis, usually in association with interstitial lung disease and arthralgia. PL-7 (Threonyl tRNA synthetase) and PL-12 (Alanyl tRNA synthetase) belong to the same family of aminoacyl-tRNA synthetases (ARS) as Jo-1. Antibodies against ARS are associated with polymyositis and dermatomyositis, they are also seen in anti-synthetase syndrome (ASS) recognized as a spectrum of myositis, interstitial pneumonia, non-erosive arthritis, fever and Raynaud's phenomena. Anti-Ro52 are the most common ENA specificity amongst autoimmune diseases. They can be seen in Sjogren's syndrome, SLE, cutaneous lupus erythematosus, neonatal lupus and primary biliary cirrhosis. SRP antibodies can be found in approximately 5% of polymyositis and dermatomyositis cases. They are also markers for necrotising myopathy which shows similar skin changes to dermatomyositis but has more acute symptoms including muscle pain/weakness and interstitial lung disease. EJ and OJ are markers for polymyositis and may be found in interstitial lung fibrosis, in overlap syndrome, arthritis and Raynaud's syndrome. EJ may also be observed in SLE.

Requestable Seperately?Yes

Minimum Sample Volume:0.5mL

Expected Turnaround Time:Frequency: Daily Target: 7 days

Test Code:MYEX

Sample Type:

Serum Gel Tube (Gold top)/ Plasma

Complex Reference Range:Positive/ Negative

Collection Conditions / Other Information:1st class post or Transport

Referred to Another Laboratory?No

Storage Requirements:Ambient temperature

NPEX / PDF Reporting Available:Yes

EQA Scheme:Yes

Lead Contact Details:rwh-tr.bcpsimmunologyclinicalqueries@nhs.net

Email Address For Chasing Results:rwh-tr.ImmunologyLab@nhs.net

Methodology:Immunoblot

UKAS Reference Number:9580 (recommended)

Site Sample Tested:Immunology, New Cross Hospital, Wolverhampton

Minimum Request Interval (MRI):180 days (6 months) over 16y only