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What is Lesch-Nyhan Syndrome? - Symptoms & Treatment

Instructor: Artem Cheprasov
How do you stop someone from hurting themselves? That's what doctors treating people with Lesch-Nyhan Syndrome must consider. This lesson describes this condition and some of its possible treatments.

What Is Lesch-Nyhan Syndrome?

Missing parts of fingers. Bitten off parts of lips. Bitten off parts of the tongue. What is being described here? A lot of things may be running through your mind, some having to do with horror movies or books or something similar. Unfortunately, all of these terrible signs are actually part of real life for people with Lesch-Nyhan Syndrome (LNS). This is a rare genetic disorder the predominantly affects males and is characterized, in part, by chronic self-mutilation.

Let's learn more about its causes, signs and treatment.

What Causes It?

So what can possibly lead to such unfortunate signs in a person? Why would someone want to hurt themselves so painfully? LNS is caused by mutations (abnormal changes) in the HPRT gene on a person's X chromosome. More than 600 of these mutations have been documented.

LNS is inherited via mutations in the X chromosome.
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The HPRT gene codes for an enzyme called hypoxanthine-guanine phosphoribosyl transferase. To keep sane for the rest of this lesson we'll just stick to calling it the HPRT enzyme. An enzyme is a molecule that speeds up biochemical reactions in the body. As a result of these mutations, however, the activity of the enzyme is virtually nil. This is a problem.

See, normally HPRT helps the body prevent the buildup of uric acid. Uric acid is a useless waste substance created as a result of the breakdown of purines by your body, such those found aplenty in many types of meats and seafood. Since the HPRT gene is mutated, the HPRT enzyme is deficient in its activity. Since this enzyme doesn't work properly, uric acid builds up in the body. This leads to a condition called hyperuricemia, or abnormally high ('hyper-') levels of uric acid ('uric') in the blood ('-emia').

Uric acid is not only a waste substance, it's a toxic waste substance. Thus, the inappropriate function of the HPRT enzyme, the hyperuricemia as well as poorly understood neuropathological (brain disease related) changes are the root cause of many of the signs and symptoms associated with LNS.

Signs

What are these signs and symptoms? Well, here is a partial list. Some of them you've already learned about in the intro.

This disorder is characterized by self-injury, such as biting one's body parts (including the tongue), head banging and stabbing oneself with sharp objects. People who suffer from LNS feel like someone else is controlling them when they do this. Worst of all in some sense? They feel pain just like all of us when this happens. They will cry and scream when injuring themselves. They also plot clever ways to hurt themselves if they are restrained. Yet people with LNS like being restrained because they know they'll be less likely to hurt themselves.

Or hurt others for that matter. People who have LNS have an irresistible urge to hurt others and objects. They may want to tear out the pages from a book placed in front of them. They will punch, swear and spit at doctors, family and friends. However, they will always apologize, even for acts they've yet to commit. They are considered very kind despite their inability to control this kind of destructive behavior.

Other potential signs and symptoms of this condition include:

  • Hypotonia, a lack of appropriate muscle tone, which can result in the inability to sit up straight or hold up one's head.
  • A slow and abnormal development of their movement-based abilities. Almost all LNS patients are wheelchair-bound and almost all cannot control many of their movements. This may manifest itself in abnormal and involuntary muscle movements, like jerking.
  • Inappropriate physical development.
  • Intellectual disability
  • Consequences of the hyperuricemia, such as gout (a type of arthritis) or uric acid crystals in the urine. Kidneys stones or kidney failure may occur as well.

Treatment

There is no cure for this disorder. Treatment is aimed at alleviating or controlling the signs and symptoms the patient presents with. A compound called allopurinol may be used to try and lower the levels of uric acid in the blood. This may help lower the chances of developing gout, which is caused by uric acid deposition in the joints. However, allopurinol doesn't correct many of the signs and symptoms of LNS.

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