Sanfilippo syndrome is a rare genetic disorder characterized by mental deterioration, mild physical defects, and behavioral problems. Sanfilippo syndrome, also considered a genetic error of metabolism, is a mucopolysaccharide disorder and is referred to as MPS - III. Mucopolysaccharides are long chains of sugar molecules which are used in building connective tissue. Typically, when the body is finished using these sugar molecules, it breaks them down with enzymes and disposes of them. Children with Sanfilippo syndrome, however, are missing the enzyme to breakdown the molecules and instead store them in cells in their body. The storage of these molecules then causes progressive damage. As a result, infants may not show signs of the disorder, but as the child grows and more cells become damaged, the symptoms become more obvious and worsen.
There are four different enzyme deficiencies that cause Sanfilippo syndrome, therefore, the syndrome is classified as being either type A,B,C, or D. Type A is caused by a deficiency of the enzyme known as heparan sulfatase and is the most severe type with earlier onset and earlier death than the others. Type A is also the most common form of Sanfilippo syndrome. Type B is the second most common, and is the result of a deficiency of the enzyme known as N-acetyl-alpha-D-glucosaminidase (NAG). Type C is caused by a deficiency in acetyl CoA: a-glucosamine N acetyl transferase and type D is caused by a deficiency in N acetyl glucosamine 6-sulphate sulphatase.
Sanfilippo syndrome was first described in 1963 by Dr. Sylvester Sanfilippo and is considered rare, with an occurrence rate of 1 out of every 25,000 live births. It is an autosomal recessive hereditary disorder in that both parents have to be carriers of the defective gene and must both pass the gene on to the child in order for the child to be affected. There is a one in four chance of having a child born with Sanfilippo syndrome when both parents are carriers. There is also a two in three chance that unaffected children will be carriers.
Features and Characteristics
Following is a list of features which have been identified in children with Sanfilippo syndrome.
- Occasional enlarged head
- Coarse facial features
- Coarse hair
- Excessive hair growth
- Joint stiffness
- Occasional short stature
- Progressive ataxia (failure of muscle coordination)
- Bulbar dysfunction
- Recurrent upper respiratory tract infections
- Severe diarrhea or constipation
- Failure to thrive
- Severe conductive hearing loss
- Aggressive and destructive behavior
- Poor attention span
- Temper tantrums
- Physical aggression
- Speech and language delay
- Sleep disturbance
- Severe intellectual impairment most often before 6 years of age
- Partial paralysis of all four limbs
- Mild growth retardation
- Vision impairment
In the beginning, it may be difficult to recognize that something is wrong in that some children do not look abnormal and their symptoms are very mild. In fact, it is not unusual for families to have more than one affected child before the diagnosis is established. A deficiency of enzyme activity in leucocytes and cultured skin fibroblasts can indicate a diagnosis of Sanfilippo syndrome.
At the present time, there is no cure for Sanfilippo syndrome. Enzyme replacement therapy and gene therapy are the two treatments that researchers have been focusing on to eventually cure Sanfilippo syndrome and other MPS diseases. There are a number of research institutions around the world working on finding a cure for the MPS diseases including facilities in the United States, Canada, England, and Australia.
What to Expect
Sanfilippo syndrome is a progressive disorder, however, the rate at which the children deteriorate varies from one individual to another. The change seen in children with Sanfilippo syndrome occurs most often very gradually, but the disorder tends to have three main stages:
In stage 1, it is noticed that the child starts to lag behind and develops difficult behavior. In stage 2, the child may become extremely active, restless, and often have very difficult behavior. Some children have sleep disturbances. Many like to chew on their hands, clothes, or other accessible items. Language and understanding will gradually become lost. Some children never become toilet trained and those who do will eventually lose the ability. In stage 3, the child will begin to slow down. They have more difficulty when walking or running and fall often, eventually losing the ability to walk altogether.
The current life expectancy for children with Sanfilippo syndrome is 14 to 20 years. However, parents should remain hopeful in that researchers are actively working on a cure to save the lives of children with this disease.
If you are interested in meeting other parents who have a child with Sanfilippo syndrome, a list of contacts can be found at: http://mpssociety.org/emailsan.htm.
For more information on Sanfilippo syndrome, please see the following references:
- The National MPS Society http://mpssociety.org/mps3.htm
- Pediatric Database (PEDBASE) http://www.icondata.com/health/pedbase/files/SANFILIP.HTM
- Online Mendelian Inheritance in Man http://www3.ncbi.nlm.nih.gov/Omim
- National Organization for Rare Disorders http://www.stepstn.com/cgi-win/nord.exe?proc=GetDocument&rectype=0&recnum=290
- The Canadian MPS Society http://www.mpssociety.ca/index.php3
- The Society for Mucopolysaccharide Diseases http://www.mpssociety.co.uk/faq_frameset.htm
The Disorder Zone has been created for educational purposes only and is not intended to serve as medical advice. The information provided in The Zone should not be used for diagnosing or treating a health problem or disease. It is not a substitute for professional care. If your child has any health concerns, please consult your health care provider.
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