Test Category: Immunology
Investigation Name:Extractable Nuclear Antigen (ENA) Blot (Profile)
Alias or Abbreviation:ENA, Ro, La, Sm, RNP, Jo-1, Scl-70
Intro:
Indication: Connective Tissue Disease (CTD) Further information: NOTE: Performed if ENA screen is equivocal or positive The ENA BLOT includes the following antigens: • rRNP/Sm • Sm • SS-A • Ro-52 • SS-B • Scl-70 • Jo-1 Ro (SSA): Significant in the clinical diagnosis of SLE (prevalence 40-50%) and Sjogren's syndrome (prevalence 60-75%). Have been reported to occur in association with certain disease subsets such as subacute cutaneous LE, neonatal lupus or vasculitis in Sjogren's syndrome. Ro52: Isolated anti-Ro-52 antibodies may be seen in healthy individuals but may also be associated with inflammatory myositis and scleroderma with an increased risk of interstitial lung disease. In pregnant women these may entail a risk for foetal congenital heart block. SSB: Serological hallmark of Sjogren's syndrome, however a small proportion of patients do remain negative. Also present in mothers of newborns with neonatal lupus. Sm: Antibodies are a highly specific but comparatively insensitive clinical marker for SLE. RNP: Antibodies appear in both SLE and mixed connective tissue disease (MCTD). In MCTD the presence of U1-snRNP antibodies is required for diagnosis, whereas they occur in only 30-40% of SLE patients. Scl70: Scl70 antibodies (anti-topoisomerase) are one of the antibodies (together with anti-centromere and RNA polymerase III) which are included in the EULAR/ACR classification criteria for systemic sclerosis. Jo-1: Jo-1 antibodies can be found as markers in dermatomyositis/polymyositis (prevalence 25%), but also in patients with polymyositis overlap syndrome. They are associated with interstitial pneumonitis (in the context of myositis) more frequent in adults than juvenile myositis. Patients with Jo-1 antibodies tend to have a severe form of the disease with a tendency to relapse and a poorer prognosis.Requestable Seperately?No
Minimum Sample Volume:1mL
Test Code:ENAB
Sample Type:
Serum Gel Tube (Gold top)/ PlasmaComplex 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
Further information:Performed if ENA screen is equivocal or positive
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
