Fukutin-related protein is essential for mouse muscle, brain and eye development and mutation recapitulates the wide clinical spectrums of dystroglycanopathies.
Recent genetic studies have shown that RYR1 variants are the most common cause of dominant and recessive congenital myopathies - central core and multi-minicore disease, congenital fiber type disproportion, and centronuclear myopathy.
More than 80 mutations in the skeletal muscle ryanodine receptor gene have been found to be associated with autosomal dominant forms of malignant hyperthermia and central core disease, and with recessive forms of multi-minicore disease.
In 7 cases with RYR1 mutations (6 CCD, one MmD), RyR1 was depleted from the cores; in contrast, the other proteins of the sarcoplasmic reticulum (calsequestrin, SERCA1/2, and triadin) and the T-tubule (dihydropyridine receptor-alpha1subunit) accumulated within or around the lesions, suggesting an original modification of the Ca-release complex protein arrangement.
Ryanodine receptor 1 (RYR1) gene mutations are associated with central core disease (CCD), multiminicore disease (MmD) and malignant hyperthermia (MH), and have been reported to be responsible for 47-67% of patients with CCD and rare cases with MmD.
Here we characterized a mouse model knocked-in for a frameshift mutation in RYR1 exon 36 (p.Gln1970fsX16) that is isogenic to that identified in one parent of a severely affected patient with recessively inherited multiminicore disease.
Mutations in the skeletal muscle ryanodine receptor (RYR1) gene are associated with a wide range of phenotypes, comprising central core disease and distinct subgroups of multi-minicore disease.
Initially described in association with malignant hyperthermia, pathogenic variants in RYR1 are typically associated with core pathology in muscle biopsies (central core disease or multiminicore disease) and symptomatic myopathies with symptoms ranging from mild weakness to perinatal lethality.
Management is mainly supportive and has to address the risk of marked respiratory impairment in SEPN1-related MmD and the possibility of malignant hyperthermia susceptibility in RYR1-related forms.