Hunter Syndrome mucopolysaccaridosis II

What is the Disease?

  • lysosomal storage disease
  • progressively debilitating disorder that affects different parts of the body
  • enzyme iduronate 2-sulfatase missing, which is responsible for breaking down large sugar molecules, called dermatan and heparan
  • buildup of these sugar molecules causes damage to body

How was it Discovered?

  • 1917 by Charles Hunter
  • described his two brothers with the disease

Incidence Rate

Hunter syndrome affects about 1 in 25,000 babies born in the United States. Globally, it affects about 1 in 100,000 to 150,000 people. It typically is only found in males because they only have one X chromosome, which is where the mutated gene, IDS is located. Females have been known to inherit Hunter Syndrome, but because it is a recessive trait and they have two X chromosomes, their incidence rate is significantly lower, unless they are born with two altered copies of the IDS gene.

Location of IDS gene

Symptoms

Hysrocephalus
  • full lips
  • large rounded cheeks
  • broad nose
  • enlarged tongue (macroglossio)
  • deep, hoarse voice
  • sleep apnea
  • large head (macrocephaly)
  • fluid in the brain (hydrocephalus)
  • enlarged liver and spleen
  • umbilical and abdominal hernias
  • white skin growths
  • hearing loss/ear infections
  • reduced vision
  • carpal tunnel syndrome
  • heart valve problems

Diagnosis

  • documentation of reduced or absent iduronate 2-sulfatase enzyme activity from blood or skin cells
  • patients accumulate heparin and dermatan sulfates in urine
  • molecular testing available to confirm diagnosis

Prognosis

  • no cure
  • severe cases-lifespan 10-20 years
  • mild cases-lifespan 20-60 years

Treatment

  • enzyme replacement therapy-replacing patients' deficient/absent enzyme with working enzyme via IV
  • other treatment is purely symptomatic (only treat symptoms of disease)

Research

In 2010, researchers began studying the use of intrathecal injections (into the spine) using a more concentrated dose of idursulfase than the one used in IVs in enzyme replacement therapy. They hope to prevent the cognitive decline associated with the condition.

Works Cited

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