for males ages 6 months to 65 years (full criteria)
at La Jolla, California and other locations
study started
estimated completion



The objectives of this study are to illustrate the clinical, neuro/electrophysiologic, biochemical, and developmental status and progression of patients with Creatine Transporter Deficiency (CTD) and to evaluate the utility of performance-based and other measures in the CTD population.


This is an observational study designed to determine an appropriate clinical assessment battery for males with CTD, and to evaluate Magnetic resonance spectroscopy (MRS) along with other potential biomarkers. It is designed to explore developmental domains of interest and to examine the feasibility and utility of various neuropsychological assessments to measure domains of interest, and to identify possible endpoints for interventional studies. Study will also explore genotype-phenotype correlations. Clinical adverse events will be monitored throughout the study. This study was previously posted by Lumos Pharma, which has been transferred to Ultragenyx in June 2019.


Creatine Deficiency, X-linked Creatine transporter developmental delay intellectual disability X-linked language seizure observational brain spectroscopy


You can join if…

Open to males ages 6 months to 65 years

  1. Subject has genomic confirmation of a pathologic mutation in the SLC6A8 gene.
  2. Subject is able to complete study-related procedures.
  3. Subjects' parents/guardians/caregivers must provide written consent (informed consent) to study-related procedures, and if appropriate, the subject will provide an assent.

You CAN'T join if...

  1. Subject has had status epilepticus within 3 months of screening.
  2. Subject is unable to comply with the study procedures or with a clinical disease or laboratory abnormality that in the opinion of the investigator would potentially increase the risk of participation.


  • University of California San Diego
    La Jolla California 92037 United States
  • University of Utah
    Salt Lake City Utah 84108 United States


in progress, not accepting new patients
Start Date
Completion Date
Ultragenyx Pharmaceutical Inc
Study Type
Last Updated