Background: Creatine transporter deficiency (CTD) is a genetic disorder that mainly affects the brain in males. CTD causes intellectual disability that can be mild to severe. People with CTD may have seizures and behavioral issues. They may have slow growth and tire easily. CTD may sometimes be confused with autism or other disorders. Better diagnostics are needed. The study team in an NIH study noted that the faces of children with CTD can look similar. For this natural history study, an expert will examine photos of children with CTD. Any shared traits found might help to diagnose CTD.

Objective: To look for shared facial features of children with CTD.

Eligibility: Males aged 2 to 40 years old with CTD who were in study 17-CH-0020.

Design: Some participants in study 17-CH-0020 had pictures taken of their faces. The NIH study team wants to share these photos with a colleague in Canada. This person is an expert at evaluating how genetic disorders affect people s bodies. Participant data collected during the study may also be sent to this expert. This data may include diagnostic images and results from lab tests. Some children did not have their pictures taken during study 17-CH-0020. Parents are asked to take pictures of these children and send them to the study team. These photos can be sent to a secure portal. The photos can also be taken in-person during a clinic visit. The photos may be printed in clinical study journals. But this is not required. Parents will be asked to sign a separate consent before the photos are published.