T Nation

ACTN3 Gene: RX, rX et Rx Distinction?

Hello CT,

for the ACTN3 gene, where did you find the distinction between RX, rX et Rx you wrote about in
https://www.t-nation.com/training/tip-actn3-the-muscle-gene

I found nothing in scientific papers (for example https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5741991/ )

Thank you in advance