SLC13A5 deficiency (Citrate Transporter Disorder, EIEE 25) is a rare genetic disorder with neurodevelopmental delays and seizure onset in the first few days of life. This natural history study is designed to address the lack of understanding of disease progression and genotype-phenotype correlation. Additionally it will help in identifying clinical endpoints for use in future clinical trials.

This is a longitudinal observational study for the natural history of SLC13A5 deficiency for up to 2 years. This study does not involve any therapeutic intervention. The study includes remote visits which will be done via telephone or remote video conferencing. Translators will be available during these remote visits for non-english speaking caregivers. The initial visit will consist of collecting a detailed medical history and medical records. Prior brain imaging and available EEGs will be collected and reviewed by the study neurologist. Neuropsychological assessments will be made using Vineland Adaptive Behavior Scale version 3. Brief standardized videos recorded by the caregiver will be reviewed and scored by study personnel for movement assessment. Caregiver of ages 2 and up will be asked to complete the QOL Family Impact Module and the QOL epilepsy module. In addition to the initial visit, assessments in 1st year (every 3 months) and 2nd year (every 4 months) of enrollment will be made through remote interviews. Caregiver will be asked to maintain a seizure diary for the duration of the study to assess seizure burden. Personnel having expertise to comprehensively evaluate biological pathways that are perturbed by SLC13A5 deficiency will analyze the collected data. Improved understanding of disease pathogenesis will guide therapeutics and reveal clinical endpoints for use in future clinical trials. Identifying genotype-phenotype correlations can guide prognostication, clinical management, and genetic counseling.

Inclusion Criteria:

1. Parent(s)/legal representative and/or patient must be willing and able to give informed consent/assent for participation in the study.
2. Males and females of any age are eligible for this study
3. Suspected or confirmed diagnosis of SLC13A5 deficiency with genetic variants in both SLC13A5 alleles and consistent clinical characteristics. Variants of uncertain significance in one or both alleles are acceptable if deemed good candidates by participant's primary geneticist or neurologist and study personnel.
4. Participant and caregiver must be willing to provide clinical data and participate in standardized assessments.

Exclusion Criteria:

1. The presence of a second, confirmed disorder, genetic or otherwise, affecting neurodevelopment or with other overlapping symptoms of SLC13A5 deficiency.

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Study population will consist of children or adolescents with genetically confirmed diagnosis of SLC13A5 Deficiency and consistent clinical characteristics.

The study data will be retained in the study-specific REDCap data base housed at redcap.stanford.edu. Researchers and clinicians with academic interest in SLC13A5 deficiency may be provided access to data obtained through this study. Any data shared outside of Stanford University will be done so in a coded fashion with no protected health information included and with the execution of all applicable agreements or ongoing collaborations as approved in this protocol.