181: Creatine Transporter SLC6A8: Conservation and Variant Impact

️ Episode 181: Creatine Transporter SLC6A8: Conservation and Variant Impact

In this episode of PaperCast Base by Base, we explore how the creatine transporter gene SLC6A8 (CRT1) is evolutionarily conserved across terrestrial mammals and how disease-associated variants alter creatine uptake in vitro, shedding light on genotype–phenotype relationships in creatine transporter deficiency. fileciteturn0file0

Study Highlights:
The authors compared CRT1 amino acid sequences among multiple species and found striking conservation, with human transmembrane domains 1–10 identical across the mammals analyzed and most interspecies differences confined to terminal or loop regions. They curated benign and pathogenic missense variants from public databases and mapped them onto CRT1, observing that missense changes in N‑ and C‑termini are more often tolerated, whereas variants within core transmembrane domains and specific loop regions are frequently pathogenic. Functional assays in transfected cells demonstrated that eight of nine tested patient variants—most located in transmembrane segments—caused severe reductions in creatine transport, while a peripheral extracellular loop variant produced a more modest decrease. Integrating intolerance profiling with phylogenetic and experimental data, the study highlights a hotspot between amino acids 305–415 and underscores strong structural constraints that shape CRT1 function.

Conclusion:
Together, these results provide a practical framework for interpreting SLC6A8 variants in the clinic and suggest that domain-aware assessments can better predict which alterations are likely to impair creatine transport and contribute to neurodevelopmental disease.

Reference:
Diep T, Lipshutz GS. Evaluation of SLC6A8 species conservation and the effect of pathogenic variants on creatine transport. Human Genetics and Genomics Advances. 2025;6:100489. https://doi.org/10.1016/j.xhgg.2025.100489

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

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