NeurometPlus

Incidence

It occur in 1/100.000 to 1/380.000. It is an X-linked inherited disorder of the purine metabolism. Only boys are affected. The gene has been located on the long arm of chromosome X

Clinical Characteristics

Pts are normal at birth. Developmental delay becomes apparent between 3-6 months. Then involuntary movements (choreiform, facial grimacing, athetosis less often) are seen between 12 and 18 months. There is motor retardation and athetosis, compulsive oral self-mutilation (usually seen between age 2 to 4 years but not always) and severe mental retardation. Axial hypotonia and limb spasticity is seen at the end of 12 months. There are many manifestations of hyperuricemia like crystalluria, nephrolithiasis, gout, and obstructive uropathy. Diapers may stain orange color. May have abdominal pain and hematuria. Allopurinol improves hyperuricemia and kidney problems but has no effect on the neurological condition. The enzyme may be partially deficient with milder symptoms. The automutilation may result in terrible disfigurement of face. Then they bite their fingers. There may be aggressiveness toward others. The automutilation may start late after age 8 yrs. and tend to improve with age. The IQ retardation is variable and some may have almost normal IQ. Speech is retarded and limited. There is severe dysarthria, dysphagia and vomiting. There is FTT. Patients never walk nor stand and many do not seat neither. 50% have seizures. Microcephaly not infrequently occur. NCV is normal. Eye media is nl. CSF is nl with increased uric acid. EEG is nl. Tofi and arthritis may occur late after 12 yrs.

Precipitants

no

Provocation Tests

no

Diagnostic Procedures

EB-R, EB-F. To determine uric acid in urine (expressed in relation to creatinine excretion: normal is less than 1 mg. In L-N disease the value is 3 to 4 mg uric acid/mg creatinine) and in blood (usually between 7 to 10 mg/dL. Pts excrete 2-3 times the normal amount of uric acid (usually 18 mg).