Mucopolysaccharidosis type I Scheie syndrome

A milder form of mucopolysaccharidosis type I

Mucopolysaccharidosis type I Scheie syndrome
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Synonyms	MPS I S
Pronounce	N/A
Specialty	N/A
Symptoms	Joint stiffness, corneal clouding, mild facial coarsening
Complications	N/A
Onset	Childhood
Duration	Lifelong
Types	N/A
Causes	Mutations in the IDUA gene
Risks	N/A
Diagnosis	Clinical evaluation, genetic testing
Differential diagnosis	N/A
Prevention	N/A
Treatment	Enzyme replacement therapy, supportive care
Medication	N/A
Prognosis	Variable, generally better than other forms of MPS I
Frequency	N/A
Deaths	N/A

Mucopolysaccharidosis type I Scheie syndrome (MPS I S) is a genetic disorder that is part of the group of diseases known as mucopolysaccharidoses. It is the mildest form of Mucopolysaccharidosis type I, which also includes Hurler syndrome and Hurler-Scheie syndrome. MPS I S is caused by a deficiency of the enzyme alpha-L-iduronidase, leading to the accumulation of glycosaminoglycans (GAGs) in the body.

Pathophysiology

MPS I S is caused by mutations in the IDUA gene, which encodes the enzyme alpha-L-iduronidase. This enzyme is responsible for breaking down GAGs, specifically dermatan sulfate and heparan sulfate. In individuals with MPS I S, the deficiency of alpha-L-iduronidase leads to the accumulation of these substances in various tissues, causing the symptoms associated with the disorder.

Clinical Features

The symptoms of MPS I S are generally milder compared to other forms of MPS I. Common clinical features include:

• Joint stiffness and limited range of motion
• Corneal clouding, which can affect vision
• Mild facial coarsening
• Carpal tunnel syndrome
• Mild skeletal abnormalities
• Heart valve abnormalities

Unlike Hurler syndrome, individuals with MPS I S typically have normal intelligence and a normal lifespan.

Diagnosis

Diagnosis of MPS I S is based on clinical evaluation, biochemical tests to measure enzyme activity, and genetic testing to identify mutations in the IDUA gene. Early diagnosis is important for managing symptoms and improving quality of life.

Treatment

Treatment for MPS I S focuses on managing symptoms and may include:

• Enzyme replacement therapy (ERT) with laronidase, which can help reduce GAG accumulation
• Physical therapy to maintain joint mobility
• Surgical interventions for carpal tunnel syndrome or heart valve abnormalities
• Regular monitoring by a multidisciplinary team

Prognosis

The prognosis for individuals with MPS I S is generally favorable compared to other forms of MPS I. With appropriate management, individuals can lead relatively normal lives, although they may experience some physical limitations.

Also see

• Mucopolysaccharidosis
• Hurler syndrome
• Hurler-Scheie syndrome
• Enzyme replacement therapy
• Genetic testing