Irreversible brain creatine deficiency with elevated serum and urine creatine: A creatine transporter defect?

Recent reports highlight the utility of in vivo magnetic resonance spectros copy (MRS) techniques to recognize creatine deficiency syndromes affecting the central nervous system (CNS). Reported cases demonstrate partial revers ibility of neurologic symptoms upon restoration of CNS creatine levels with the administration of oral creatine. We describe a patient with a brain cr eatine deficiency syndrome detected by proton MRS that differs from publish ed reports. Metabolic screening revealed elevated creatine in the serum and urine, with normal levels of guanidino acetic acid. Unlike the case with o ther reported creatine deficiency syndromes, treatment with oral creatine m onohydrate demonstrated no observable increase in brain creatine with proto n MRS and no improvement in clinical symptoms. In this study, we report a n ovel brain creatine deficiency syndrome most likely representing a creatine transporter defect.