Sanfilippo syndrome is a genetic error of metabolism. It is a mucopolysaccharidoses, an MPS disorder, MPSlll. Mucopolysaccharides are long chains of sugar molecules, which are used in building connective tissues. When the body is finished using these molecules, it breaks them down, with enzymes, and disposes of them. Children with Sanfilippo syndrome are missing or are deficient in the enzyme to break down the molecules. Instead, the body stores these molecules in the cells.This storage causes progressive damage.
There are four different types of Sanfilippo syndrome. Each type is different and named according to which enzyme is missing or defective.
- Sanfilippo Type A is the most common. It is considered the most severe type with earlier death than the others. These children are deficient in the enzyme Heparan N-sulfatase.
- Sanfilippo Type B is the second most common. This is the result of a deficiency in N-acetyl-alpha-D-glucosaminidase.
- Sanfilippo Type C is caused by a deficiency in Acetyl-CoAlpha-glucosaminide acetyltransferase.
- Sanfilippo Type D is caused by a deficiency in N-acetylglucosamine 6-sulfatase.
Sanfilippo syndrome was first described in 1963 by Dr. Sylvester Sanfilippo and is considered rare, with an occurrence of 1 in every 70,000 births. It is an autosomal recessive hereditary disorder, which means, both parents must be carriers in order for the child to be affected. There is a one in four chance of having a child born with Sanfilippo syndrome. There is a two in three chance that unaffected children will be carriers.
Sanfilippo syndrome is a progressive disorder, meaning that at birth the children appear typical and do not show signs of the disorder. As the disease progresses the children degenerate, losing the ability to speak, walk, eat and eventually lose their lives.
In the first stage of the disorder it is noticed that the child lags behind and develops behavioral issues.
In the second stage, 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 and clothing. Language and understanding will gradually become lost.
In the third stage the child begins to slow down. They have difficulty walking, falling often eventually losing the ability to walk altogether.
Most children experience seizures, joint stiffness, upper respiratory infections, hearing loss, dementia, hyperactivity, aggressive behavior, severe intellectual impairment, partial paralysis, growth retardation and vision impairment.
The current life expectancy is 10-20 years.