A person with an inherited autosomal recessive disease has two mutated genes.If this person has a child with a person who is not a carrier of the mutated gene, all the children will inherit the mutated gene but they will not have the disorder.Mucopolysaccharide depositions in the meninges (the membranes that cover the brain and spinal cord) prevent normal drainage of cerebrospinal fluid, thereby leading to the development of hydrocephalus.The abdomen protrudes owing to enlarged liver and spleen, and inguinal (groin) or umbilical hernias are common.They are classified in accordance with the degree of symptom severity, Hurler syndrome being the most severe form and Scheie the mildest. Deficiency of the enzyme alpha-L-iduronidase thus causes a spectrum of symptoms, depending on the underlying genetic anomaly (mutation).The rare disease database of the Swedish Board of Health and Welfare has separate information on other MPS disorders: Hunter (MPS II), Sanfilippo (MPS III), Maroteaux- Morquio (MPS IV), Lamy (MPS VI), and Sly (MPS VII) syndromes.These saccharides, with their long carbohydrate chains, are components of various tissues.Breakdown of the mucopolysaccharides normally takes place in the cell lysosomes, small units found in all cells except red blood cells.
Hurler syndrome was described for the first time in 1919, by the German paediatrician Gertrud Hurler.There are currently around 10-15 people with the syndrome in Sweden (2012). An English study suggests an incidence of 1 per 500,000 newborns.There are currently no known cases of Scheie syndrome in Sweden, but there are a few individuals with this form of MPS in Norway and Denmark.This means that both parents are healthy carriers of a mutated gene.When two healthy carriers have a child, there is a 25 per cent risk that the child will inherit the mutated genes (one from each parent), in which case he or she will have the disease.
Newborns with the syndrome appear healthy and develop normally until they are between 6 months and two years old, when organ damage is first detected.