The NM_005629.4(SLC6A8):c.89C>T (p.Ala30Val) variant in SLC6A8 is a missense variant predicted to cause substitution of Alanine for Valine at amino acid 30 (p.Ala30Val). In gnomAD v2.1.1, the highest population minor allele frequency is 0.001205 (1/830 alleles) in the European population with 1 hemizygote, which is <0.0002 and >1 hemizygote, therefore PM2_Supporting criteria is not applicable. The computational predictor REVEL gives a score of 0.096 which is below the threshold of 0.25, and does not predict a damaging effect on SLC6A8 function, and SpliceAI predicts no impact on splicing (BP4). This variant has not been previously reported in affected individuals in the literature. There is a ClinVar entry for this variant (Variation ID:650071). In summary, this variant meets the criteria to be classified as a Variant of Uncertain Significance for Creatine Transporter Deficiency based on the ACMG/AMP criteria applied, as specified by the ClinGen Cerebral Creatine Deficiency Syndromes Variant Curation Expert Panel (Specifications Version 1.1.0): BP4. (Classification approved by the ClinGen CCDS VCEP on June 6, 2022).