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Lesch Nyhan syndrome is a condition characterized by neurological and behavioral abnormalities and the overproduction of uric acid in the body. It occurs almost exclusively in males. Signs and symptoms may include inflammatory arthritis (gout), kidney stones, bladder stones, and moderate cognitive disability. Nervous system and behavioral disturbances also occur, such as involuntary muscle movements and self injury (including biting and head banging). People with Lesch Nyhan syndrome usually cannot walk, require assistance sitting, and generally use a wheelchair. Lesch Nyhan syndrome is caused by changes (mutations) in the HPRT1 gene and is inherited in an X-linked recessive manner. Treatment is symptomatic and supportive. Affected people often do not survive past the first or second decade of life due to renal failure.
Source: GARD Last updated on 05-01-20
Lesch Nyhan syndrome is inherited in an X-linked recessive manner. A condition is X-linked if the changed (mutated) gene responsible for the condition is located on the X chromosome. The X chromosome is one of the two sex chromosomes; females have two X chromosomes, and males have one X and one Y chromosome. Females who have one mutated copy of the responsible gene (on one of their X chromosomes) usually do not have the condition and are referred to as carriers. This is because they still have a working copy of the responsible gene on their other X chromosome. Males with one mutated copy of the responsible gene have signs and symptoms of the condition (they are affected) because they do not have another X chromosome with a working copy of the gene. This is why X-linked recessive disorders, including Lesch Nyhan syndrome, occur much more frequently in males.
Lesch Nyhan syndrome is caused by mutations in the HPRT1 _gene. A female who is a carrier of Lesch Nyhan syndrome has a 50% chance of passing on the mutated _HPRT1 gene in each pregnancy. This is because a carrier female will randomly pass on one of her X chromosome to each child. Sons who inherit the mutated gene will be affected, and daughters who inherit the mutated gene will be carriers. This means that with each pregnancy, a female who is a carrier has a:
Last updated on 05-01-20
With advanced planning and appropriate testing, it may be possible for a carrier to prevent having a child with Lesch Nyhan syndrome. Depending on each person's individual situation and choices, this may be accomplished either during a pregnancy, or before a pregnancy begins.
To find out whether a fetus is affected during a pregnancy, prenatal testing can be performed either by molecular genetic testing or biochemical genetic testing. Molecular genetic testing may be done if the specific mutation in the HPRT1 gene has been identified in the family. The usual procedure is to first determine fetal sex by performing chromosome analysis on fetal cells obtained by chorionic villus sampling (at about 10 to 12 weeks gestation), or by amniocentesis (usually performed at about 15 to 18 weeks gestation). If the fetus is known to be male, DNA from fetal cells can then be tested for the mutation in the family. If the specific mutation in the HPRT1 gene in the family is not known, biochemical genetic testing is preferred. This testing also requires either chorionic villus sampling or amniocentesis, but involves measuring HPRT enzyme activity in the cells obtained during the procedure. If Lesch Nyhan syndrome is confirmed in the fetus by either method of testing, pregnancy options including pregnancy termination may be discussed with a health care provider.
As an alternative to prenatal diagnosis during the pregnancy, preimplantation genetic diagnosis (PGD) before a pregnancy may be available if the mutation in the family is known. PGD is done after in vitro fertilization (IVF) to diagnose a genetic condition in an embryo before it is introduced into the uterus. When having PGD, only embryos known to be unaffected are introduced into the uterus for a possible pregnancy.
People interested in genetic testing, prenatal diagnosis, and/or preimplantation genetic diagnosis should speak with a genetics professional.
Last updated on 05-01-20
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