A crippling genetic disorder
Lesch - Nyhan syndrome, first described by Michael Lesch and William Nyhan in 1964 is the clinical presentation of a defect of the enzyme hypoxanthine-guanine phosphoribosyl transferase (HPRT), leading to an overproduction of Uric Acid in the patients blood. As the disease is genetic and influences an important part of the human metabolism, onset is quite early: most children present between 3 and 12 months. There are three prevalent clinical features of Lesch - Nyhan Syndrome: growth retardation, neurological features including impaired IQ, involuntary movements and spasms and behavioural problems, most strikingly a tendency to self-biting.
The patients rarely reach their fourtieth birthday and, apart form their unusual features and behaviour can suffer from the classic symptoms of hyperuricaemia, including kidney stones and renal failure. The genetic defects happen on the X - chromosome (meaning near all cases are male) and are heterogenous, meaning that different mutations of the gene (i.e. single base substitution, deletions, insertions and substitutions) can cause the same clinical picture.
Treatment is unsatisfactory: Allopurinol can reduce uric acid levels and Benzodiazepines and Baclofen can alleviate the neurological symptoms. Incidence internationally of Lesch - Nyhan Syndrome is 1 per 380,000 patients.