Lesch-Nyhan Syndrome

What is Lesch-Nyhan syndrome?

Lesch-Nyhan syndrome is a condition characterised by the overproduction of uric acid, a nitrogen-containing compound found in urine. Problems with the nervous system and behavioural disturbances are characteristic of this disorder. The overproduction of uric acid can cause gouty arthritis (arthritis caused by uric acid in the joints), as well as kidney and bladder stones. Abnormal involuntary muscle movements such as flexing, jerking, flinging, and flailing are often displayed. Self-injury through biting and head banging is the most common behavioural problem in Lesch-Nyhan patients.

How common is Lesch-Nyhan syndrome?

The prevalence of Lesch-Nyhan syndrome is approximately 1 in 380,000 individuals. This condition occurs with a similar frequency in all populations.

What genes are related to Lesch-Nyhan syndrome?

Mutations in the HPRT1 gene cause Lesch-Nyhan syndrome.

Mutations in the HPRT1 gene cause a shortage (deficiency) of the enzyme hypoxanthine phosphoribosyltransferase 1. This enzyme is responsible for recycling purines, a type of building material for DNA and its chemical cousin RNA. When this enzyme is lacking, the breakdown of purines results in abnormal levels of uric acid buildup in the body. The mechanism by which high uric acid levels cause neurological and behavioural disturbances is currently not well understood.

How do people inherit Lesch-Nyhan syndrome?

This condition is inherited in an X-linked recessive pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome (one of the two sex chromosomes). In males, who have only one X chromosome, one altered copy of the gene is sufficient to cause the condition. In females, who have two X chromosomes, a mutation must usually be present in both copies of the gene to cause the disorder. Males are affected by X-linked recessive disorders much more frequently than females. A striking characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.

Among males with Lesch-Nyhan, the X chromosome that carries the mutation is inherited from the mother, who is referred to as an unaffected carrier. Other females in the mother's family may also carry the mutation.

What other names do people use for Lesch-Nyhan syndrome?

• Choreoathetosis self-mutilation syndrome
• Complete HPRT deficiency
• Complete hypoxanthine-guanine phosphoribosyltransferase deficiency
• HPRT - Hypoxanthine-guanine phosphoribosyltransferase deficiency
• hypoxanthine phosphoribosyltransferse (HPRT) deficiency
• Juvenile gout, choreoathetosis, mental retardation syndrome
• juvenile hyperuricemia syndrome
• Lesch-Nyhan Disease
• LNS
• primary hyperuricemia syndrome
• Total HPRT deficiency
• Total hypoxanthine-guanine phosphoribosyl transferase deficiency
• X-linked hyperuricemia
• X-linked primary hyperuricemia
• X-linked uric aciduria enzyme defect