Hurler syndrome

Hurler syndrome: Description, Causes and Risk Factors: Alternative Names: Hurler disease, lipochondrodystrophy, type IH mucopolysaccharidosis, MPS IH, Pfaundler-Hurler syndrome. Hurler syndromeMucopolysaccharidoses (MPS) are a group of progressive hereditary disorders of connective tissue metabolism in which lysosomal enzyme deficiency leads to intralysosomal deposition of mucopolysaccharides or glycosaminoglycans in the airway, cornea, brain, heart, liver, spleen, bones, ligaments, blood vessels, skin producing various symptoms. Seven different types of mucopolysaccharidosis have been described and categorized into syndromes according to both the clinical features and demonstrated enzyme deficiencies. Hurler syndrome or MPS 1H is the prototype of MPS and is the most severe form of it. In Hurler's syndrome airway problem has been described as the worst in Pediatric Anesthesia. Perioperative mortality rates averaging 20% have been reported for patients with this disease, with failure to control the airway as the largest single cause of mortality. Approximately 1 in 150,000 infants are affected. Newborn infants with this defect appear normal at birth. By the end of the first year, signs of impending problems begin to develop. Hurler syndrome is caused by deficient alpha-L-iduronidase (-L-iduronidase) activity, which results in an accumulation of the glycosaminoglycan (GAG) heparan sulfate and dermatan sulfate in body tissues. People affected by Hurler syndrome are unable to produce a substance called, 'lysosomal alpha-L-iduronidase.' The substance is an enzyme that assists in breaking down long chains of sugar molecules called glycosaminoglycans. These sugar molecules are located throughout the person's body, many times in the person's mucus and in the fluid around the person's joints. Without the lysosomal alpha-L-iduronidase enzyme, glycosaminoglycans build up in the affected person's system and cause damage to their organs, to include their heart. Hurler syndrome is inherited in an autosomal recessive pattern. A child inherits the syndrome when he or she gets two abnormal genes that affect the IDUA enzyme, one from each parent. If only one parent passes on the gene mutation, the child will not have the disease. Instead, the child will be a "carrier" and may pass the gene mutation to his or her own children. Symptoms: Clinical features of hurler syndrome include coarse facial features, dysostosis multiplex, short stature, hirsutism, cloudy corneas, and hepatosplenomegaly, and cardiac complications. Developmental delay and intellectual disability is more severe in those patients with Hurler syndrome and is a distinguishing features between the subtypes of MPS I. General symptoms may include: Short stature.
  • Coarse facies.
  • Enlarged tongue.
  • Enlarged skull.
  • Skeletal defects.
  • Corneal clouding.
  • Hearing impairment.
  • Mental retardation.
  • Inguinal hernias.
  • Joint stiffness and skeletal deformities
  • Coronary heart disease.
  • Hepatosplenomegaly.
Diagnosis: A diagnosis of Hurler Syndrome is typically made by measuring alpha-L-iduronidase enzyme activity. Molecular analysis of the IDUA gene can be performed to confirm the biochemical diagnosis. Once the mutations are identified in the proband, carrier testing and prenatal diagnosis can be offered to at risk family members. Sequencing of the IDUA gene identified a mutation in about 97% of abnormal alleles in of individuals with a biochemical diagnosis. Other exams and tests may include: Electrocardiogram (EKG).
  • Genetic testing for the alpha-L-iduronidase gene.
  • Urine tests for extra mucopolysaccharides.
  • X-ray of the spine.
Treatment: Because Hurler syndrome is genetic, it is difficult to cure. The goal of treatment is to give the body the missing enzyme so it can break down GAGs. The two main treatments for children with Hurler syndrome are enzyme replacement therapy (ERT) and a bone marrow or cord blood transplant. In ERT, a patient is given a drug that has the IDUA enzyme his or her body is missing. Enzyme replacement therapy may be a good option for children who have a form of MPS I disorder that does not cause mental retardation. A bone marrow or cord blood transplant (BMT) is the only known treatment that can stop the progression of mental damage caused by this disease. A transplant is an intense treatment, and some possible side effects may include: Graft-versus-host disease (GVHD).
  • Graft failure.
  • Bleeding in the lungs (pulmonary hemorrhage).
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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