Identification and clinical characteristics of a novel missense ADGRG1 variant in bilateral Frontoparietal Polymicrogyria: The electroclinical change from infancy to adulthood after Callosotomy in three siblings

Epilepsia Open. 2023 Mar;8(1):154-164. doi: 10.1002/epi4.12685. Epub 2023 Jan 11.


Objective: Bilateral frontoparietal polymicrogyria (BFPP) is a rare genetic-related migration disorder. It has been attributed to loss-of-function of the ADGRG1 gene, which encodes an adhesion G protein-coupled receptor, ADGRG1/GPR56. We report the EEG findings of BFPP in three Asian patients, and confirmed that change in protein function was caused by the novel missense variant (p.Leu290Pro).

Methods: We reviewed the medical records of three siblings with BFPP including one elder girl and two identical twin boys from birth to adulthood. The clinical symptoms, electroencephalography (EEG), brain MRI, whole-exome sequencing, treatment including medications, neuromodulation, and epilepsy surgery, and clinical outcomes were reviewed. The protein structure of a novel missense variant (p.Leu290Pro) was predicted by in silico studies, and molecular analysis was performed via typical flow cytometry and Western blotting.

Results: The elder girl (Patient 1) was 22 years old and the twin boys (Patients 2 and 3) were 20 years old at the time of publication. All of them presented with typical clinical symptoms/signs and MRI findings of BFPP. Whole-exome sequencing followed by Sanger confirmation showed that all three patients had compound heterozygous variants in the ADGRG1 gene. The missense variant (p.Leu290Pro) was confirmed to be related to a reduction in cell surface GPR56 expression. High-amplitude rhythmic activity was noted in sleep EEG during infancy, which may have been due to excessive sleep spindle, and the rhythm disappeared when they were of pre-school age. Partial callosotomy provided short-term benefits in seizure control in Patients 1 and 2, and combined vagus nerve stimulation and partial callosotomy provided longer benefits in Patient 3.

Significance: Sleep EEG findings of high-amplitude rhythmic activity in our BFPP cases were only noted during infancy and childhood. We also confirmed that the missense variant (p.Leu290Pro) led to loss of function due to a reduction in cell surface GPR56 expression.

Keywords: congenital CNS malformation; epilepsy; genetic; polymicrogyria.

Publication types

  • Review
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Child
  • Child, Preschool
  • Female
  • Humans
  • Infant
  • Male
  • Mutation, Missense
  • Polymicrogyria*
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / metabolism
  • Siblings
  • Young Adult


  • Receptors, G-Protein-Coupled

Supplementary concepts

  • Polymicrogyria, Bilateral Frontoparietal