Congenital Myasthenic Syndrome (RAPSN-Related) (RAPSN)
Congenital myasthenic syndrome (RAPSN-related) is an autosomal recessive disease that is found in different populations, but has a higher prevalence in the Caucasian population as well as Sephardic Jewish populations from Iraq and Iran. It is caused by pathogenic variants in the RAPSN gene. The disease is characterized by skeletal muscles that weaken upon physical exertion, particularly the muscles of the face and limbs. The severity of the symptoms can vary widely among individuals. Disease severity correlates with the age of onset, which may be in infancy, childhood, or adulthood. Due to muscle weakness, affected infants may have difficulty feeding and delayed achievement of developmental milestones. Lifespan is generally normal, although severely affected individuals may have respiratory complications. No genotype-phenotype correlation has been observed.
For information about carrier frequency and residual risk, please see the residual risk table.