Hunter syndrome – causes, symptoms, diagnosis, treatment, pathology

Learning medicine is hard work! Osmosis makes it easy. It takes your lectures and notes to create
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much more. Try it free today! Hunter syndrome is a rare genetic metabolic
disorder that occurs when lysosomal enzymes are absent. Hunter syndrome is also known as mucopolysaccharidosis
type 2. Mucopolysaccharides or glycosaminoglycans
are types of complex sugars, which are produced by the cells and exported to the extracellular
space. Examples include heparan sulfate and dermatan
sulfate. Both heparan sulfate and dermatan sulfate
can be found on almost all cell surfaces as well as in the basement membrane, which separates
epithelial cells from the connective tissue that lies beneath. When mucopolysaccharides like heparin sulfate
and dermatan sulfate need to get degraded, they are taken over to a lysosome, which contains
enzymes needed to break down the mucopolysaccharides. Each mucopolysaccharide requires multiple
enzymes to fully degrade, and some mucopolysaccharides share certain enzymes in common. For example, both heparan sulfate and dermatan
sulfate need the iduronate sulfatase and alpha-L-iduronidase enzymes to get broken down. Hunter syndrome is caused by a deficiency
in iduronate sulfatase, and the result is that heparan sulfate and dermatan sulfate
can’t be degraded, so they build up in various tissues. Hunter Syndrome is an X-linked recessive disorder
so it’s more common in males. Early symptoms appear in infants, and they
include an enlarged liver and spleen leading to abdominal hernias and recurrent ear infections. Later symptoms include a prominent forehead,
a flat nose bridge, enlarged lips, tongue, and gums, thickened heart valves, obstructive
lung disease; stiff joints, and short stature due to disrupted bone growth. Hunter syndrome also classically causes skin
changes where ivory or skin colored skin ridges appear on the limbs, which make the skin look
like it is covered in tiny pebbles. In severe cases, the central nervous system
is affected, causing symptoms of ADHD, autism, OCD, as well as general aggression and mental
disability. The screening for Hunter syndrome can be done
by measuring glycosaminoglycans in urine or enzyme levels of iduronate sulfatase in the
blood. Hunter syndrome can be treated with enzyme
replacement therapy or bone marrow transplantation, depending on the severity. Additional supportive care is done by treating
the various conditions that develop like surgical correction for hernias, heart valve replacement,
respiratory support, speech therapy, and hearing aids which can all improve quality of life. All right, as a quick recap – Hunter syndrome
is due to the lack of iduronate sulfatase, and this leads to the buildup of heparan sulfate
and dermatan sulfate in various tissues. The classic symptom for Hunter Syndrome is
pebbled skin. Hunter syndrome is diagnosed by measuring
glycosaminoglycans and enzyme activity. It is usually treated with enzyme replacement
and bone marrow transplantation.

10 comments

  1. Dear sir.
    Hi!
    sir i m very much appreciate your and Dr Najeeb services in concern field.
    you both systematically and diagramatically give lecture which memorizing very beautifully
    thanks a lot.
    but i am very little doctor
    b/s my qualification is B.A, D.A.E(CIVIL) And
    HEALTH(2 years diploma).
    Sir
    I want to become a big doctor but how please little guide me what i can do in the age of 28year.
    any one can guide me?

  2. Very nice👍🏼
    Plz make a detailed video of epidermAl keratins, lamellar bodies and desmosomes etc.
    Thanks in advance.

  3. THANK YOU .. 🙂
    Insha'allah i wish to follow all you videos ; may be this will help me being a good doctor 🙂

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