Deficiency of the interleukin-1–receptor antagonist

Deficiency of the interleukin-1–receptor antagonist (DIRA) is an autosomal recessive, genetic autoinflammatory syndrome resulting from mutations in IL1RN, the gene encoding the interleukin 1 receptor antagonist. The mutations result in an abnormal protein that is not secreted, exposing the cells to unopposed interleukin 1 activity. This results in sterile multifocal osteomyelitis, periostitis (inflammation of the membrane surrounding the bones), and pustulosis due to skin inflammation from birth.

Symptoms and signs

Cervical vertebrae

DIRA displays a constellation of serious symptoms which include respiratory distress, as well as the following:

• Joint swelling
• Hepatomegaly
• Osteomyelitis
• Fused cervical vertebrae
• Interstitial pulmonary abnormality
• Stomatitis
• Mouth ulcers
• Pustulosis or pustular psoriasis
• Cerebral vasculitis
• Joint pain
• Splenomegaly

Cause

Those affected with DIRA have inherited (via autosomal recessive manner) mutations in IL1RN, a gene that encodes a protein known as interleukin 1 receptor antagonist, The cytogenetic location of IL1RN is 2q14.1, while its 2:113,099,364-113,134,015 are the genomic coordinates

Mechanism

Interleukin-1Alpha

The mechanism of deficiency of the interleukin-1–receptor antagonist affects the normal function of IL1RN gene.The protein produced by IL1RN gene prevents the normal activities of interleukin 1(alpha) and interleukin 1(beta). Therefore, the pathophysiologic immune and inflammatory responses are nullified. Interleukin 1 receptor antagonist(IL1RN) has a total of five alleles, of those the (IL1RN*1) and (IL1RN*2) are the most common as the other alleles are seen less than 5 percent.

IL-1RN binds to the same cell receptors as the inflammatory protein IL-1, and blocks its inflammatory actions. Without IL-1Ra, the body cannot control systemic inflammation that can be caused by IL-1.

Diagnosis

Those affected with deficiency of the interleukin-1–receptor antagonist can have diagnosis achieved via noting an increase of erythrocyte sedimentation rate, as well as the following:

• Genetic test
• Radiological findings
• Clinical findings

Treatment

Colchicine

In terms of treatment a 2013 review indicates that colchicine can be used for DIRA. Additionally there are several other management options such as anakinra, which blocks naturally occurring IL-1, this according to a 2016 pediatric textbook.

See also

• Neonatal onset multisystem inflammatory disease (NOMID)

External links

Classification	OMIM: 612852
External resources	Orphanet: 210115

• PubMed