Extractable Nuclear Antigen Screen / Type (ENAS)

Department of Immunology

Performed after a positive ANA.
Important markers in the diagnosis of many rheumatological conditions. Screen contains Ro (SSA), La (SSB), Sm, U1 RNP, Jo-1 and Scl-70. If screen is positive typing will automatically be performed.
Ro (SS-A) antibodies are seen in Sjogren's syndrome (in 60-75%) and SLE (in 40-50%), particularly subacute cutaneous. Also linked to neonatal lupus and congenital heart block.
La (SS-B) antibodies are found mainly in Sjogren's syndrome. Also sometimes seen in SLE, neonatal lupus and congenital heart block.
Sm antibodies are highly specific for SLE.
U1-RNP antibodies appear in mixed connective tissue disease and 30-40% of SLE patients.
Jo-1 antibodies can be found in dermatomyositis / polymyositis (in 25%) and in patients with polymyositis overlap syndrome. They are associated with interstitial pneumonitis (in the context of myositis).
Scl-70 antibodies are found in 25% of patients with autoimmune myositis and 68% with anti-synthetase syndrome.

Clotted blood. (No patient preparation or special handling required).

Adult

5ml Gold-top SST tube or 3.5ml Rust-top gel tube (Trust users only)

Paediatric

1ml Serum Sample

10 days

3 days

3 months for screen and 6 months for typing

Normal = Negative

Updated: April 2026