Understanding Mucopolysaccharidosis Type I (MPS I): Causes, Symptoms, and Treatment Options

Mucopolysaccharidosis Type I, or MPS I, is a rare genetic disorder that affects children. It is caused by a deficiency in an enzyme called alpha-L iduronidase, which is responsible for breaking down certain sugars in the body. When these sugars build up, they can cause damage to various organs and tissues, leading to a range of symptoms.

Causes of MPS I

MPS I is an inherited disorder, meaning it is passed down through families. A child can only develop MPS I if both parents carry a defective gene and pass it on to their child. If a child inherits one normal gene and one defective gene, they will not have symptoms of MPS I but may pass the gene on to their own children.

Symptoms of MPS I

The symptoms of MPS I can vary depending on the severity of the condition. In milder cases, symptoms may not appear until later in childhood, while in more severe cases, symptoms can be present in infancy. Some common symptoms of MPS I include:

• Distinctive facial features, such as a large head, bulging forehead, and flat nose

• Short stature and stocky build

• Stiff joints and limited mobility

• Breathing problems and frequent respiratory infections

• Eye problems, such as cloudy corneas and vision loss

• Hearing loss and frequent ear infections

• Enlarged liver or spleen

• Heart disease

• Developmental delays and intellectual disability (in severe cases)

Diagnosing MPS I

Because MPS I is a rare disorder, doctors may initially rule out other conditions before making a diagnosis. If MPS I is suspected, the doctor may perform tests to measure the levels of certain sugars in the child's urine or to assess the activity of the alpha-L iduronidase enzyme in their blood or skin cells. Once a diagnosis is confirmed, it is important to inform extended family members, as they may also carry the defective gene.

Treatment Options for MPS I

While there is no cure for MPS I, there are treatments available that can help manage symptoms and slow the progression of the disease. The two main treatment options are:

1. Enzyme Replacement Therapy (ERT)

ERT involves the use of a synthetic version of the missing enzyme, called laronidase (Aldurazyme). This treatment can help relieve many of the symptoms of MPS I and slow the progression of the disease, although it does not treat symptoms related to the brain, such as cognitive impairment.

2. Hematopoietic Stem Cell Transplant (HSCT)

HSCT involves transplanting healthy stem cells, usually from bone marrow or umbilical cord blood, into the child's body. These cells can produce the missing enzyme, potentially improving cognitive function if performed early enough. However, HSCT does not address bone or eye problems associated with MPS I.

It is important to work with a specialist experienced in treating lysosomal storage diseases like MPS I. Depending on the child's specific symptoms, they may also need to see other specialists, such as a cardiologist or ophthalmologist.

Living with MPS I

Children with MPS I can benefit from a supportive environment that encourages independence and social interaction. Families should work with their child's school to develop an individualized education program (IEP) that addresses their specific needs. Home modifications may also be necessary to improve accessibility and independence.

Caregivers should also prioritize their own well-being and seek support when needed. Organizations like the National MPS Society can provide valuable resources and connect families with others living with MPS I.

While the prognosis for MPS I varies depending on the severity of the condition, early diagnosis and treatment can significantly improve quality of life. With proper care and support, many children with milder forms of MPS I can lead fulfilling lives, attending school, and even starting families of their own.