New Compound Heterozygous Splice Site Mutations of the Skeletal Muscle Ryanodine Receptor (RYR1) Gene Manifest Fetal Akinesia: A Linkage with Congenital Myopathies

Mutations in the skeletal muscle ryanodine receptor (RYR1) gene have been linked to malignant hyperthermia susceptibility, central core disease, and minicore myopathy with external ophthalmoplegia.RYR1is an intracellular calcium release channel and plays a crucial role in the sarcoplasmic reticulum and transverse tubule connection. Here, we report 2 fetuses from the same parents with compound heterozygous mutations in theRYR1gene (c.10347+1G>A and c.10456-2 Alpha>G) who presented with fetal akinesia and polyhydramnios at 27 and 19 weeks of gestation with intrauterine growth restriction in the third pregnancy. The prospective parents of the fetuses were heterozygous carriers for c.10456-2 Alpha>G (mother) and c.10347+1G>A (father). Both mutations affect splice sites resulting in dysfunctional protein forms probably missing crucial domains of the C-terminus. Our findings reveal a newRYR1splice site mutation (c.10456-2 Alpha>G) that may be associated with the clinical features of myopathies, expanding theRYR1spectrum related to these pathologies.