Compatible with a loss of fast twitch fibres, muscle biopsies from patients with AD-RYR1-related CCD showed a significant decrease in MYH1, MYH2 and TNNT3 (mean log2-fold changes were −6.43 adjusted P = 9.09E − 07, −4.13 adjusted P = 7.29E − 04 and −5.10 adjusted P = 2.36E − 05, respectively; Fig. 2E), whereas those from AR RYR1-related MmD/CNM showed a significant increased expression of TTN (the mean log2-fold change was 1.13 adjusted P = 0.03; Fig. 2F). Here, TNNT3 is linked to Alzheimer disease.