A Novel Missense Variant in the AGRN Gene; Congenital Myasthenic Syndrome Presenting With Head Drop

J Clin Neuromuscul Dis. 2017 Mar;18(3):147-151. doi: 10.1097/CND.0000000000000132.

Abstract

Congenital myasthenic syndromes (CMS) are a heterogeneous group of diseases of the neuromuscular junction caused by compromised synaptic transmission. Clinical features include early-onset weakness of limbs and oculobulbar muscles resulting in hypotonia, bulbar paresis, ptosis, and hypoventilation. The first dropped head syndrome in children were detected in 2 patients with LMNA and SEPN1 mutations. We report a 17-month-old boy with dropped head and limb-girdle weakness, who had no ptosis or ophthalmoplegia at presentation. We performed whole exome sequencing, which revealed a homozygous missense variant in the AGRN gene c.5023G>A, p.Gly1675Ser in the LG2 domain, which is predicted to be likely disease causing by in silico tools. Agrin is known to play a critical role in the development and maintenance of the neuromuscular junction. Agrin-related CMS is one of the rarest subtypes. Of note, our patient is the first described patient with agrin-related CMS with dropped head phenotype.

Publication types

  • Case Reports

MeSH terms

  • Agrin / genetics*
  • Child, Preschool
  • DNA Mutational Analysis
  • Exome
  • Humans
  • Infant
  • Male
  • Mutation, Missense*
  • Myasthenic Syndromes, Congenital / genetics*

Substances

  • Agrin