Features of Mucopolysaccharidosis Syndromes– Hunter syndrome:-
- Type- II
- 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 –
- Mode of inheritance (X – linked).
- Absence of corneal clouding.
- Milder clinical course..Results from deficiency of iduronate – 2 – sulfatase (I2S).
- 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:
coarse facial features and short stature.
enlarged liver and spleen.
progressive and profound mental retardation.
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.
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.
- 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.
- 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.
1.SHAFERS 8th edition
2.NEVILLE ‘S 3rd edition