Hunter syndrome

Features of Mucopolysaccharidosis Syndromes Hunter syndrome:-

  • Type- II
  • Eponym-Hunter.
  • Inheritance- X-Linked R.
  • Enzyme Defi ciency- Iduronate-2-sulfatase.Stored Substrate- HS heparan sulfate and DS DS, dermatan sulfate.
  • Clinical Features – Appears at 1 to 2 years of age; clear corneas, reduced intelligence, growth retardation, stiff joints
  • Differs from Hurler’s syndrome in –

  1. Mode of inheritance (X – linked).
  2. Absence of corneal clouding.
  3. Milder clinical course..Results from deficiency of iduronate – 2 – sulfatase (I2S).
  4. Without enough I2S, partially broken-down mucopolysaccharides accumulate in the organs and tissues of the body and become toxic.

Clinical features :-

  • Hunter syndrome is divided into two types.

I-   Type A is he severe form, which usually is diagnosed in children aged 18-36 months.

  • Considered the classic form.
  • Children with type A may survive into the second and third decades of life.
  • Symptoms in type A may include:

  1. coarse facial features and short stature.

  2. enlarged liver and spleen.

  3. progressive and profound mental retardation.

  4. ivory-colored skin lesions on the upper back and sides of the upper arms and thighs.skeletal changes, joint stiffness, short neck, broad chest, and too-large head.

  5. progressive deafness.

  6. atypical retinitis pigmentosa and visual impairment.

II.Type B Hunter syndrome is much milder than type A

  • May not be diagnosed until adulthood.
  • Individuals with type B may live into their 70s.
  • Their physical features are similar to those in type A.
  • Individuals with type B, however, usually have normal intelligence and do not have the severe skeletal problems of type A.

Diagnosis:-

  • In type A Hunter syndrome, the child’s appearance combined with other symptoms such as enlarged liver and spleen and the ivory-colored skin lesions can suggest the child has mucopolysaccharidosis.
  • Type B Hunter syndrome is much harder to identify, and might only be recognized when looking at the maternal relatives of a child with Hunter syndrome.
  • In either type, the diagnosis can be confirmed by a blood test for deficiency of I2S.

Treatment:-

  • Medical care is directed towards relieving the symptoms of Hunter syndrome.
  • Treatment with Elaprase (idursulfase) replaces I2S in the body and helps reduce symptoms and pain.

References:-

1.SHAFERS 8th edition

2.NEVILLE ‘S 3rd edition

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