Erythrocyte assays for hypoxanthine guanine phosphoribosyltransferase (HGPRT) activity performed on two male half-siblings with hyperuricemia, produced results consistent with classic Lesch-Nyhan syndrome. Due to the absence of neurologic abnormalities, cognitive deficits, or self-mutilation, HGPRT activity was measured by intact fibroblast assay which revealed partial enzyme deficiency. The presence of an unstable mutant enzyme may have led to the discrepancy between the erythrocyte and fibroblast studies. This discrepancy emphasizes the difficulty in assaying this enzyme solely utilizing red blood cell studies to determine a patient's course. In order to provide an accurate prognosis and relevant genetic counseling, measurement of this enzyme utilizing intact fibroblasts is critical after establishing a diagnosis of HGPRT deficiency in a hyperuricemic male lacking typical clinical manifestations of Lesch-Nyhan syndrome, but having enzyme activity of erythrocytes consistent with the diagnosis.

Child, Preschool↗

PubMedDate not supplied

Familial iridoplegia.

Fixed, dilated pupils in childhood are usually due to interruption of parasympathetic innervation as a result of neurologic impairments or occur following pharmacologic mydriasis. We present a familial form of iridoplegia without structural defects of the eye which is consistent with a probable autosomal dominant mode of inheritance. Examination of other family members should be part of an affected individual's evaluation particularly when this finding occurs as an isolated defect. Recognition of such an entity may avoid unnecessary neurodiagnostic studies in an affected individual.

Child, Preschool↗