Non-type I cystinuria associated with mental retardation and ataxia in a Korean boy with a new missence mutation(G173R) in the SLC7A9 gene.

[cystinuria]

Cystinuria is an inherited renal and intestinal disease characterized by defective amino acids reabsorption and cystine urolithiasis . It is unusually associated with neurologic symptoms . Mutations in two genes , SLC 3 A 1 and SLC 7 A 9 , have been identified in cystinuric patients . This report presents a 13 -yr -old boy with cystinuria who manifested difficulty in walking , ataxia , and mental retardation . Somatosensory evoked potential of posterior tibial nerve stimulation showed the central conduction dysfunction through the posterior column of spinal cord . He was diagnosed non-type I cystinuria by urinary amino acid analysis and oral cystine loading test . We screened him and his family for gene mutation by direct sequencing of SLC 3 A 1 and SLC 7 A 9 genes . In this patient , we identified new missence mutation G 173 R in SLC 7 A 9 gene .