Eosinophil peroxidase deficiency (Eosinophil peroxidase deficiency) - Gen EPX.

Eosinophil peroxidase deficiency is a disorder that affects eosinophils, and does not cause health problems in affected individuals. In eosinophil peroxidase deficiency, eosinophils have little or no eosinophil peroxidase protein. Deficiency of this protein does not appear to affect the ability of eosinophils to participate in an immune response. Because this alteration does not cause any health problems, often diagnosed when blood tests are done for other reasons or when a family member has been diagnosed with the disease.

This process is due to mutations in the gene EPX, located on the long arm of chromosome 17 (17q23.1). This gene encodes the protein eosinophil peroxidase, located inside eosinophils. During a normal immune response, eosinophils are activated and moved to the site of injury or inflammation. Subsequently, cells release proteins and other compounds which have a toxic effect that damages the cells or invading organisms. Eosinophil peroxidase protein helps form molecules that are highly toxic to bacteria and parasites. These toxic molecules also play a role in the regulation of inflammation by combating microbial invaders. Eosinophil peroxidase protein is produced as a long strand that splits into two smaller units. The shorter unit is known as the light chain, while the other unit is known as the heavy chain. These two parts are connected together to form functional eosinophil peroxidase.

They have been described at least three mutations in the gene EPX deficient individuals eosinophil peroxidase. These mutations reduce or inhibit eosinophil peroxidase coding or give rise to a protein that is nonfunctional and unstable. Cells lacking eosinophil peroxidase are smaller and may have structural changes, but the other proteins within the affected eosinophils are normal and eosinophil peroxidase loss does not appear to affect the function of these cells.

This disease is inherited in an autosomal recessive pattern, that is, both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.

Tests in IVAMI: in IVAMI perform detection of mutations associated with eosinophil peroxidase deficiency, by complete PCR amplification of the exons of the gene EPX, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).