A 28-year-old man presents with recurrent gouty arthritis since his early twenties and urate nephrolithiasis. Serum uric acid is markedly elevated. Neurological examination, behavior, and intelligence are entirely normal, and there is no self-injurious behavior. Assay of red cell lysate shows residual hypoxanthine-guanine phosphoribosyltransferase activity at about 5 percent of normal. What is the most likely diagnosis?

• A Complete HGPRT deficiency (Lesch-Nyhan syndrome)
• B Purine nucleoside phosphorylase deficiency
• C Adenine phosphoribosyltransferase deficiency
• D Kelley-Seegmiller syndrome ✓

Explanation

Kelley-Seegmiller syndrome is partial HGPRT deficiency with enough residual enzyme activity to prevent the neurological and behavioral features of Lesch-Nyhan disease, leaving severe hyperuricemia with gout and nephrolithiasis as the phenotype. Complete HGPRT absence would produce self-mutilation and choreoathetosis, which are absent here.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.