Inherited Immune System Disorders

Inborn errors of metabolism are a diverse group of disorders caused by an inherited deficiency or defect in a single enzyme or protein. Your body needs these vital enzymes and proteins. When there are not enough of them, the body cannot break down certain large molecules correctly. As a result, a harmful amount of these large molecules, or “storage materials,” builds up and damages organs and body systems. If you have inborn errors of metabolism you often develop nerve deterioration. These disorders may also impair your heart, vision, hearing, bone growth, lungs and muscles. Children with these disorders may need multiple surgeries and restricted activities. They may also have growth problems and persistent discomfort. These inherited immune system disorders include:

X-Linked Adrenoleukodystrophy

X-Linked Adrenoleukodystrophy (X-ALD) is a rare genetic disorder that only affects males. The genetic defect impairs your body’s ability to break down certain fats, causing them to build up in your body. This affects how your adrenal glands, testes and central nervous system work. 

The myelin sheath — the layer of insulation that protects nerves in the body — breaks down, causing nerve cells to lose their ability to work. About 40 percent of boys with ALD experience this disorder in the brain, called cerebral ALD (cALD). Early signs of the problems include hyperactivity, poor school performance and a short attention span.

Leukodystrophies

Leukodystrophies are a group of rare, progressive, metabolic, genetic diseases that affect your brain, spinal cord and often the peripheral nerves. Each type of leukodystrophy is caused by a specific gene abnormality that leads to abnormal development or destruction of the white matter (myelin sheath) of your brain. 

The myelin sheath is the protective covering of the nerve and nerves can't function normally without it. Each type of leukodystrophy affects a different part of the myelin sheath, leading to a range of neurological problems.

Metachromatic Leukodystrophy

Metachromatic Leukodystrophy (MLD) is a rare inherited disorder in which a missing enzyme leads to a buildup of a fat called sulfatide in the body. The myelin sheath — the layer of insulation that protects nerves — breaks down, causing nerve cells to lose their ability to work. Children who develop MLD between the ages of 6 months and 2 years have what is called late infantile MLD. They may show a change in gross motor skills, such as walking. They may also lose their ability to speak, move or swallow. 

Children with juvenile MLD begin to show symptoms between ages 4 and 12 — such as problems walking or standing up straight, emotional difficulties, trouble following directions, and poorer school performance. Adult MLD arises as early as the teen years and may be misdiagnosed as a mental health issue because the person may develop personality changes, anxiety, and an impaired memory.

Mucopolysaccharidosis Type 1

Mucopolysaccharidosis Type 1 (MPS-1) is also known as Hurler syndrome and is the most severe form of MPS-1. It occurs when an enzyme needed to break down certain long chains of sugar molecules is missing. The sugars build up in many tissues in the body, which causes life-threatening organ damage. 

Most children with Hurler syndrome begin to show symptoms between the ages of one and 2, such as frequent colds and ear infections, noisy breathing, changes in bone growth and facial features, vision and hearing problems, and issues affecting the heart, liver and spleen. 

Treatment with a stem cell transplant early in life is the only way to stop the disease from progressing. A donor’s healthy cells provide a continual supply of the missing normal enzyme, halting organ damage.