Rare immune system disorders

Our body has an immune system that protects us from infections.

Weaknesses in the immune system are called immunodeficiency disorders. These weaknesses lead to susceptible individuals suffering from more severe, frequent or unusual infections, compared with the average person.

When the weakness is due to a mutation in the genes, this is called a primary immunodeficiency disorder.

Genes are blueprints used by cells in our bodies to produce the components needed for our body to function properly.

Though such problems are rare, they cause significant problems to the individuals who are affected.

A study in Singapore, published 13 years ago, estimated that out of every 37,000 children born alive, one child would have a primary immunodeficiency disorder.

Severe combined immunodeficiency (SCID) refers to the most severe form of primary immunodeficiency disorder, where affected children suffer devastating infections in the first year of life.

Death in infancy or early childhood is common if this condition is not diagnosed.

Omenn syndrome is an extremely rare form of SCID, where there are features of inflammation as well as the immunodeficiency. Left untreated, it is fatal. It is thought to occur in fewer than one in a million people.

In addition to its rarity, diagnosis can be made more difficult because the key features may not appear until later on.

• Source: Dr Soh Jian Yi, Consultant, Division of Paediatric Allergy, Immunology & Rheumatology, National University Hospital

A version of this article appeared in the print edition of The Straits Times on June 17, 2016, with the headline 'Rare immune system disorders'. Print Edition | Subscribe