Differentials
Cerebral palsy
SIGNS / SYMPTOMS
Owing to the occurrence of hypotonia and developmental delay early in the course of the disease, many patients are diagnosed as having cerebral palsy until the tell-tale features of Lesch-Nyhan disease (LND), such as self-injury or overproduction of uric acid, are recognised.
INVESTIGATIONS
Hyperuricaemia is not typical in cerebral palsy.
Hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene analysis and HPRT enzyme activity will provide definite diagnosis in cases of LND.
Diseases with developmental delay
SIGNS / SYMPTOMS
The differential diagnosis for developmental delay is extensive.[32]
LND should be suspected if delayed development is accompanied by self-injurious behaviour or evidence of excessive production of uric acid.
INVESTIGATIONS
Hyperuricaemia is not typical in these conditions.
HPRT gene analysis and HPRT enzyme activity will provide definite diagnosis in cases of LND.
Diseases with dystonia at young age
SIGNS / SYMPTOMS
The differential diagnosis for dystonia at young age is extensive.[33]
LND should be suspected if dystonia is accompanied by self-injurious behaviour or evidence of excessive production of uric acid.
INVESTIGATIONS
Hyperuricaemia is not typical in these conditions.
HPRT gene analysis and HPRT enzyme activity will provide definite diagnosis in cases of LND.
Other diseases with self-injury (e.g., intellectual disability, autism, Prader-Willi syndrome, fragile X syndrome)
SIGNS / SYMPTOMS
Self-injury in LND is usually more severe than in other conditions, and the prominent topographical preference for mouth and fingers is not frequently seen in other conditions.[34]
Self-injurious behaviour in LND is always accompanied by profound motor impairment. LND should be suspected when self-injurious behaviour is associated with the typical motor dysfunction emerging early in life, especially if there is also hyperuricaemia.[Figure caption and citation for the preceding image starts]: Examples of self-injurious behaviour seen in patients with classic Lesch-Nyhan diseaseFrom the collection of H.A. Jinnah, MD, PhD; used with permission [Citation ends].
INVESTIGATIONS
Hyperuricaemia is not typical in these conditions.
HPRT gene analysis and HPRT enzyme activity will provide definite diagnosis in cases of LND.
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