The parents of a 1-year-old boy are alarmed at the increasing frequency of their child biting his lips and finger tips. In addition, on several occasions they have noticed what appear to be particles of “orange sand” in their son’s diapers. They report to their pediatrician that they believe their child is delayed in acquiring motor skills such as holding up his head and sitting unaided. Clinical tests performed on serum and urine indicate a threefold increase in serum uric acid and a tenfold elevation in the urinary ratio of uric acid to creatinine. These findings are suggestive of which of the following disorders?
(A) adenosine deaminase deficiency
(B) adenylosuccinate lyase deficiency
© Lesch-Nyhan disease
(D) purine nucleotide phosphorylase deficiency
(E) orotic aciduria