Loss of function of JPH1, which encodes junctophilin, causes congenital myopathy

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Four individuals from unrelated consanguineous families, two of European origin, one of Khmer origin and one of Middle Eastern origin all presented with congenital myopathy with:

  • neonatal hypotonia, difficulty sucking, cleft palate, club feet ;
  • generalized weakness predominantly in the lower limbs;
  • myopathic facies, bilateral ptosis, ophthalmoplegia and fatigability;
  • muscle biopsy revealed a predominance of type 1 fibers, slightly reduced triads and sarcoplasmic reticulum abnormalities;
  • genomic analysis revealed homozygous loss-of-function variants of the JPH1 gene, which encodes junctophilin 1, a protein that connects T-tubules and the sarcoplasmic reticulum to form triads.

 

Loss-of-function variants in JPH1 cause congenital myopathy with prominent facial and ocular involvement. Johari M, Topf A, Folland C et al. J Med Genet. 2024 Aug 28:jmg-2024-109970.

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