Definition

What is Sialidosis?

Sialidosis is a rare inherited metabolic disorder characterized by a deficiency of the enzyme neuraminidase (sometimes referred to as sialidase). Deficiency of neuraminidase results in the abnormal accumulation of toxic materials in the body.

Sialidosis is divided into two types, which are distinguished by the age at which symptoms appear and the severity of features:

  • Sialidosis type I: the less severe form of this condition. People with this condition typically develop signs and symptoms of sialidosis in their teens or twenties.
  • Sialidosis type II: the more severe type of the disorder, is further divided into congenital, infantile, and juvenile forms. his type of sialidosis often begins during infancy or later during childhood.

How common is Sialidosis?

Sialidosis affects males and females in equal numbers. The exact incidence of sialidosis in the general population is unknown. One estimate places the incidence at 1 in 4.2 million individuals in the Australian population. Another estimate placed the incidence at 1-4 individuals per 200,000 of the general population. Because rare disorders like sialidosis often go unrecognized or misdiagnosed, determining the true frequency of sialidosis in the general population is difficult. Please discuss with your doctor for further information.

Symptoms

What are the symptoms of Sialidosis?

Sialidosis type I: Characteristic features may include:

  • Sudden involuntary muscle contractions (myoclonus),
  • Distinctive red spots (cherry-red macules) in the eyes
  • Certain neurological findings

Sialidosis type II: Characteristic features may include:

There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.

When should I see my doctor?

If you or your loved one has any signs or symptoms listed above or you have any questions, please consult with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.

Causes

What causes Sialidosis?

Sialidosis type I and type II are all caused by mutations in the NEU1 gene:

  • Individuals with sialidosis type I have mutations that affectsome functional NEU1 enzyme.
  • People with sialidosis type II have mutations that severely reduce or eliminate NEU1 enzyme activity.

NEU1 gene is present in the short arm of chromosome 6. The NEU1 gene is responsible for production of an enzyme called neuraminidase. The function of this enzyme is to facilitate lysosomes to break down complex compounds like fats, carbohydrates, and sugars.

Due to this faulty gene, there is deficiency of the neuraminidase enzyme, making the lysosomes unable to break down the complex fats and carbohydrates. This incident results in fats and carbohydrates being accumulated in the tissues of the body, including the brain, spinal cord, and other important organs.

When this abnormal accumulation reaches a level of being toxic, it causes Sialidosis.

Risk factors

What increases my risk for Sialidosis?

Sialidosis is an autosomal recessive trait meaning that two copies of the faulty gene one from each parent is required for development of the condition. Please consult with your doctor for further information.

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is Sialidosis diagnosed?

A diagnosis of sialidosis is made based upon identification of characteristic symptoms, a detailed patient history, a thorough clinical evaluation and a variety of specialized tests. An examination of urine may reveal increased levels of oligosaccharides. A urine test is usually followed up by blood tests and a skin biopsy (surgical removal and microscopic study of skin tissue). These tests can reveal low levels of the enzyme alpha-neuraminidase in blood and skin tissue.

For families with a previous history of sialidosis, prenatal diagnosis is available through amniocentesis. During amniocentesis, samples of fluid surrounding the fetus are removed. Fetal tissue samples may be obtained during a procedure known as chorionic villus sampling. Certain cells (fibroblasts) are cultured grown in the laboratory and evaluated for alpha-neuraminidase activity.

How is Sialidosis treated?

There is no specific therapy for sialidosis. Treatment is directed toward the specific symptoms that are apparent in each individual.

Anti-seizure medications (anti-convulsants) may be used to treat myoclonic seizures, but are not always effective.

Genetic counseling may be of benefit for affected individuals and their families. Other treatment is symptomatic and supportive.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage Sialidosis?

If you have any questions, please consult with your doctor to better understand the best solution for you.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Sources

Review Date: February 6, 2018 | Last Modified: February 6, 2018

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