Autosomal recessive hyper IgE syndrome

Other Names: DOCK8 deficiency; Hyperimmunoglobulin E recurrent infection syndrome, autosomal recessive; HIES autosomal recessive; AR-HIES; AR hyperimmunoglobulin E syndrome; Hyper Ig E syndrome, autosomal recessive

Autosomal recessive hyper IgE syndrome (AR-HIES) is a very rare primary immunodeficiency syndrome characterized by highly elevated blood levels of immunoglobulin E (IgE), recurrent staphylococcal skin abscesses, and recurrent pneumonia. The same features are also seen in the more frequent autosomal dominant HIES syndrome. DOCK8 immunodeficiency syndrome is also commonly called autosomal recessive hyper-IgE syndrome. However, researchers have identified several conditions that feature elevated levels of IgE and that follow an autosomal recessive pattern of inheritance. Each of these conditions has its own set of additional signs and symptoms and a different genetic cause. Some doctors consider these conditions forms of hyper-IgE syndrome, while others consider them independent disorders.

Epidemiology

AR-HIES accounts for only a small minority of HIES cases, with about 130 affected families reported so far.

Cause

DOCK8 immunodeficiency syndrome is caused by mutations in the DOCK8 gene. The protein produced from this gene plays a critical role in the survival and function of several types of immune system cells. One of the functions of the DOCK8 protein is to help maintain the structure and integrity of immune cells called T cells and NK cells, which recognize and attack foreign invaders, particularly as these cells travel to sites of infection within the body. In addition, the DOCK8 protein is involved in chemical signaling pathways that stimulate other immune cells called B cells to mature and produce antibodies, which are specialized proteins that attach to foreign particles and germs, marking them for destruction.

DOCK8 gene mutations result in the production of little or no functional DOCK8 protein. Shortage of this protein impairs normal immune cell development and function. It is thought that T cells and NK cells lacking DOCK8 protein are abnormal and die too easily, particularly when moving through the layers of skin. A shortage of these immune cells impairs the immune response to foreign invaders, accounting for the severe skin infections common in DOCK8 immunodeficiency syndrome. A lack of DOCK8 protein also impairs B cell maturation and the production of antibodies. Impairment of this type of immune response leads to recurrent respiratory tract infections in people with this disorder. It is unclear how DOCK8 gene mutations are involved in other features of DOCK8 immunodeficiency syndrome, such as the elevation of IgE levels, and neurological problems.

Inheritance

Autosomal recessive inheritance, a 25% chance

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Signs and symptoms

The condition is characterized by recurrent infections that are severe and can be life-threatening. The infections can be caused by bacteria, viruses, or fungi. Skin infections cause rashes, blisters, accumulations of pus (abscesses), open sores, and scaling. People with DOCK8 immunodeficiency syndrome also tend to have frequent bouts of pneumonia and other respiratory tract infections. Other immune system-related problems in people with DOCK8 immunodeficiency syndrome include an inflammatory skin disorder called eczema, food or environmental allergies, and asthma.

DOCK8 immunodeficiency syndrome is characterized by abnormally high levels of an immune system protein called immunoglobulin E (IgE) in the blood; the levels can be more than 10 times higher than normal for no known reason. IgE normally triggers an immune response against foreign invaders in the body, particularly parasitic worms, and plays a role in allergies. It is unclear why people with DOCK8 immunodeficiency syndrome have such high levels of this protein. People with DOCK8 immunodeficiency syndrome also have highly elevated numbers of certain white blood cells called eosinophils (hypereosinophilia). Eosinophils aid in the immune response and are involved in allergic reactions.

Some people with DOCK8 immunodeficiency syndrome have neurological problems, such as paralysis that affects the face or one side of the body (hemiplegia). Blockage of blood flow in the brain or abnormal bleeding in the brain, both of which can lead to stroke, can also occur in DOCK8 immunodeficiency syndrome.

People with DOCK8 immunodeficiency syndrome have a greater-than-average risk of developing cancer, particularly cancers of the blood or skin.

Diagnosis

Elevated IgE is the hallmark of HIES. An IgE level greater than 2,000 IU/mL is often considered diagnostic. However, patients younger than 6 months of age may have very low to non-detectable IgE levels. Eosinophilia is also a common finding with greater than 90% of patients having eosinophil elevations greater than two standard deviations above the normal mean. Genetic testing is available for STAT3 (Job's Syndrome), DOCK8 (DOCK8 Immunodeficiency or DIDS), PGM3 (PGM3 deficiency), SPINK5 (Netherton Syndrome - NTS), and TYK2 genetic defects.

Treatment

Most patients with hyper IgE syndrome are treated with long-term antibiotic therapy to prevent staphylococcal infections. Good skin care is also important in patients with hyper IgE syndrome. High-dose intravenous gamma-globulin has also been suggested for the treatment of severe eczema in patients with HIES and atopic dermatitis.

NIH genetic and rare disease info

• NIH info on Autosomal recessive hyper IgE syndrome

Autosomal recessive hyper IgE syndrome is a rare disease.

Autosomal recessive hyper IgE syndrome Resources
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