Brief Summary

Study Purpose:

This study is designed to characterize how males with CTD perform on neurodevelopmental assessments and to explore magnetic resonance spectroscopy (MRS) and event-related potentials (ERPs) to inform the use of these methodologies in future assessments of therapeutic agents for this disorder.  

Study Objectives:

To assess clinical characteristics by administering the following scales:
- Aberrant Behavior Checklist (ABC)
- Mullen Scales for Early Learning (MSEL)
- Vineland Adaptive Behavior Scales – Third Edition (Vineland III)
- Social Communication Questionnaire (SCQ)
- Clinical Global Impression of Severity (CGI-S)
- Parenting Stress Index (short form) – Fourth Edition (PSI-4)
- Wechsler Abbreviated Scale of Intelligence – Second Edition (WASI-II)
- Attention Deficit Hyperactivity Rating Scale (ADHD-RS-5)
- NIH Gastrointestinal questionnaire
- NIH Toolbox cognitive and motor battery (optional)
- Peabody Picture Vocabulary Test, Fourth Edition (PPVT-4) (optional)
- Expressive Vocabulary Test, 2nd edition (EVT-2) (optional)
• To assess seizure characteristics and frequency
• To assess auditory event-related potentials (ERPs) following stimulus (i.e., presentation of
a sound)
• To identify candidate imaging biomarkers for CTD using proton (1H) and/or phosphorous
(31P) MRS
• To collect biological samples in order to perform proteomic, metabolomics and genomic
analyses of physiological fluids including blood, urine, and cerebrospinal fluid (CSF)
• To obtain a skin biopsy, from which induced pluripotent stem (IPS) cells and cultured
fibroblasts may be isolated
• Correlate disease severity with genetic, metabolic and other factors
• To identify potential subjects for future interventional studies
STUDY DESIGN This is an observational study designed to determine an appropriate clinical

Inclusion Criteria

1. Subject is male and between 6 months and 65 years of age, inclusive.
2. Subject has genomic confirmation of a pathologic mutation in the SLC6A8 gene.
3. Subject is able to complete study-related procedures.
4. Subjects’ parents/guardians/caregivers must provide written consent (informed consent) to
study-related procedures.

Exclusion Criteria

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.