Sanfilippo Syndrome: A Rare and Devastating Disorder

Sanfilippo Syndrome

One way to help children suffering from some of the so-called rare diseases is to make them known. By knowing the stories of families who experience them, can help to invest in research projects and improve the quality of life of those who suffer.

Sanfilippo Syndrome is a rare and devastating disease that affects one in every 50,000 births. It is one of the more than forty lysosomal diseases, that is, those caused by the dysfunction of a lysosomal enzyme. The condition is also known as Mucopolysaccharidosis type III (MPS III).

This is a disorder of absence or malfunction of cell enzymes necessary to break down. This genetic failure causes cells to be unable to decompose the material (heparan sulfate).

Causing mental deterioration, hyperactivity, and self-destructive tendencies, leading to premature death during adolescence.

What is disconcerting about Sanfilippo syndrome is that its symptoms are not easily identifiable. So we may confuse with other disorders such as attention deficit disorder (ADD), hyperactivity, and learning difficulties.

In general, in the first years, the growth of the child is normal. There may be some signs such as slight hepatomegaly (pathological enlargement of the liver), caries, chronic rhinitis, repeated infections of the upper airways and chronic diarrhea, but nothing too noticeable.

Symptoms of Sanfilippo Syndrome

  • Aggressiveness
  • Hyperactivity and behavior disorders
  • Sleep disorders (difficulty falling asleep, sleeping speech)
  • Sudden changes in mood
  • Difficulty in learning the language
  • Chronic diarrhea
  • Respiratory infections
  • There may be problems in learning to walk and in balance, joint stiffness (they do not stretch completely)
  • Lips and thick eyebrows and rough facial features

When it is suspected that the child may suffer from Sanfilippo Syndrome (named after the scientist who discovered it), a urine test is performed in search of high concentrations of heparan sulfate, the substance that accumulates abnormally in the cells.

If the test is confirmed, a blood test is done to identify the deficient enzyme. Depending on which enzyme is lacking, the subtype of the disease is determined, which can be A, B, C or D.

At present, there is no specific treatment for this disease, which causes neurological damage, severe delay and complications such as blindness and seizures.

Sanfilippo Syndrome

Causes of Sanfilippo syndrome

Sanfilippo syndrome occurs when there is a lack of defects in the substances (enzymes) necessary to break down the chain of heparan sulfate sugars.

There are four main types of Sanfilippo syndrome, also called MPS III. The particular type a person has depends on which enzyme is affected.

  • Sanfilippo type A syndrome is the most severe form. People with this type of lack or have an altered form of an enzyme called heparan N-sulphatase.


  • Sanfilippo type B syndrome occurs when a person lacks or does not produce enough alpha-N-acetylglucosaminidase.


  • Sanfilippo syndrome type C occurs when a person lacks or does not produce enough acetyl-CoAlfa-glucosaminide acetyltransferase.


  • Sanfilippo syndrome type D occurs when a person lacks or does not produce enough N-acetylglucosamine 6-sulfatase.

Sanfilippo syndrome is transmitted as an autosomal recessive trait, which means that both parents have to transmit the defective gene to their child so that he develops the disease.

Sanfilippo syndrome is possibly the most common form of MPS. The fact of having a family history of this syndrome increases the risk of suffering from this condition.

Diagnostic tests for Sanfilippo syndrome

A physical examination or medical check-ups may show signs of inflammation of the liver and spleen.  An eye examination will show clear corneas, unlike the opaque corneas saw in people with Hurler’s syndrome (MPS IH). Neurological tests will reveal signs of seizures and mental retardation.

Urine tests performed. People with Sanfilippo syndrome have large amounts of a mucopolysaccharide, called heparan sulfate, in the urine.

Other exams can be:

  • Blood culture
  • Echocardiogram
  • Eye exam with a slit lamp
  • A culture of skin fibroblasts
  • X-rays of the bones

Treatment of Sanfilippo syndrome

In the treatment of mucopolysaccharidoses, symptomatic treatment of each symptom which is being expressed is carried out first. Furthermore, mucopolysaccharidoses of type I, type II, type IV, type VI are supplemented with enzyme replacement therapy that supplements the deficient enzyme.

Sanfilippo Syndrome

Enzyme replacement therapy

Enzyme replacement therapy is a treatment method that supplements the deficient enzyme as medicine into the body and needs to be done continually.

The earlier the time of implementation, the more effective it is, it is possible to suppress the progression and progression of various symptoms by supplementing the enzyme every week before symptoms progress.

However, complete lesions and central nervous symptoms cannot be treated only with enzyme replacement therapy. Some patients rarely have side effects such as rash, headache, feeling sick, etc.

In that case, please drop the infusion rate, stop the infusion slowly, gradually return the pace of treatment and take appropriate measures Some cases can be improved by doing.

There may be cases where you can receive enzyme replacement therapy also in rural areas

Since enzyme replacement therapy must be performed once a week, it is a heavy burden to patients and their families.

Especially if you are a local patient and you do not have a special medical institution in the vicinity, you may be worried about it, but only at the time of introduction of enzyme replacement therapy, please come to a special facility such as our hospital (see below) At some stage you may receive enzyme replacement therapy at your medical institution near your place of residence.

This means that a pharmaceutical company manufacturing an enzyme preparation goes to a medical institution and lectures on enzyme replacement therapy to doctors and nurses so that local patients can receive enzyme replacement therapy once a week.

Enzyme replacement therapy is not a complicated procedure and can be received without problems so it would be better to consult a doctor if you live in a rural area.

Bone marrow transplantation (hematopoietic stem cell transplantation)

We will consider bone marrow transplantation (hematopoietic stem cell transplantation) if it is about 2 years old before the lesion is completed. Bone marrow transplantation (hematopoietic stem cell transplantation) is a treatment that can be expected to suppress the progress of the symptoms of the brain and heart.

When bone marrow transplantation is performed, and hematopoietic stem cells engraft, it becomes possible to make enzymes by themselves, so it is possible to lower the frequency of enzyme replacement therapy. However, it is also accompanied by risks of infection and rejection, so patients need to understand it before treatment.

Development of a therapy that would reduce the burden on patients and their families is desired

Currently, enzyme replacement therapy, which is the standard treatment for mucopolysaccharidosis, has a significant influence on the patient’s quality of life (quality of life) as it requires weekly hospital visits.

Also, transplantation of hematopoietic stem cells by bone marrow transplantation has the risk of infectious diseases and rejection as mentioned above, and it is also necessary to look for donors. It is hoped that a new treatment method will be developed that will alleviate the burden on patients and their families as much as possible.

A treatment method (gene therapy) using the patient’s bone marrow is being developed

Currently, we are researching therapeutic methods of gene therapy that utilize patient’s bone marrow. This is a method of incorporating a normal gene into a patient’s bone marrow using a safely modified virus vector and then returning it to the body; the enzyme activity improves rather than using other bone marrow, It is also expected to affect the valvular heart.

Also, using your bone marrow will eliminate the risk of infection and rejection, and you will not have to look for a donor. We have started clinical trials in some diseases in Europe and the United States, and I think that this treatment will become one of the options even in mucopolysaccharidosis in the future.

The prognosis

The syndrome causes significant neurological symptoms, such as severe retardation, and the IQ can be below 50. Most people with this syndrome live until the teenage years; some may live longer, while others with severe forms of the disease die at a younger age. The symptoms seem more severe in people with Sanfilippo syndrome type A.

Possible complications

  • Blindness
  • Inability to take care of oneself
  • Mental retardation
  • Neurological damage that slowly worsens and that in the long run requires the use of a wheelchair
  • Seizures

When to call a specialist doctor

Check with your doctor if the child does not seem to be growing or developing normally.

Also, request a medical appointment if you are planning to have children and have a family history of Sanfilippo syndrome.


Sanfilippo syndrome is a hereditary disease, so if there is a family history, genetic counseling is recommended before conception. Nowadays, thanks to the techniques of preimplantation genetic diagnosis, a method to detect genetic and chromosomal anomalies in the embryo, a pregnancy can be achieved by eliminating the risk of disease.

On the other hand, during pregnancy, a core biopsy can be performed between weeks 12 and 15 of pregnancy or an amniocentesis between 15 and 16 to determine a prenatal diagnosis.

Living with a child with Sanfilippo syndrome or with another rare pathology is a constant struggle, a story of improvement, both for the patient and for the rest of their family. From Babies and more, we hope to contribute our little grain of sand by making them known.

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