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Updated: Feb 24, 2026
Identification and Classification of Position-specific GABAA Receptor Subunit Missense Variants for Their Role In Hippocampal Pyramidal Neurons
Published on: June 6, 2025
PAFAH1B1 haploinsufficiency disrupts GABA neurons and synaptic E/I balance in the dentate gyrus
Matthew T Dinday1, Kelly M Girskis1, Sunyoung Lee2
1Epilepsy Research Laboratory, Department of Neurological Surgery, University of California San Francisco, San Francisco, USA.
Insights
Mutations in the platelet-activating factor acetylhydrolase IB subunit alpha (Pafah1b1) gene disrupt GABAergic interneuron migration in mice, leading to altered brain circuit excitability and cognitive deficits.
Area of Science:
- Neuroscience
- Developmental Biology
- Genetics
Background:
- Hemizygous mutations in the Pafah1b1 gene cause lissencephaly, a severe cortical development disorder.
- Lissencephaly is characterized by neuronal migration deficits, intellectual disability, epilepsy, and early mortality.
- The precise impact of Pafah1b1 mutations on neuronal subpopulations and brain circuits remains largely unknown.
Purpose of the Study:
- To investigate the effects of Pafah1b1 deficiency on neuronal migration and function in the developing brain.
- To elucidate the impact of Pafah1b1 mutations on hippocampal circuit excitability and associated cognitive functions.
Main Methods:
- Utilized Pafah1b1+/- mouse models to study neuronal migration and synaptic function.
- Employed whole-cell patch-clamp recordings to assess synaptic inputs onto hippocampal granule cells.
- Analyzed the density of specific interneuron populations (parvalbumin, somatostatin, calretinin) in the dentate gyrus.
Main Results:
- Tangential migration of GABAergic interneurons into the hippocampus was impaired in Pafah1b1+/- mice.
- A decreased density of parvalbumin- and somatostatin-positive interneurons was observed in the dentate gyrus of mutant mice.
- Increased excitatory and decreased inhibitory synaptic inputs onto granule cells were detected, alongside spontaneous seizures and contextual memory deficits.
Conclusions:
- Pafah1b1 deficiency causes significant alterations in hippocampal circuit excitability.
- These excitability shifts may underlie the epilepsy and cognitive impairments observed in lissencephaly.
- The study highlights the critical role of Pafah1b1 in regulating interneuron migration and synaptic balance during brain development.
Abstract:
Hemizygous mutations in the human gene encoding platelet-activating factor acetylhydrolase IB subunit alpha (Pafah1b1), also called Lissencephaly-1, can cause classical lissencephaly, a severe malformation of cortical development. Children with this disorder suffer from deficits in neuronal migration, severe intellectual disability, intractable epilepsy and early death. While many of these features can be reproduced in Pafah1b1+/- mice, the impact of Pafah1b1+/- on the function of individual subpopulations of neurons and ultimately brain circuits is largely unknown. Here, we show tangential migration of young GABAergic interneurons into the developing hippocampus is slowed in Pafah1b1+/- mice. Mutant mice had a decreased density of parvalbumin- and somatostatin-positive interneurons in dentate gyrus, but no change in density of calretinin interneurons. Whole-cell patch-clamp recordings revealed increased excitatory and decreased inhibitory synaptic inputs onto granule cells of Pafah1b1+/- mice. Mutant animals developed spontaneous electrographic seizures, as well as long-term deficits in contextual memory. Our findings provide evidence of a dramatic shift in excitability in the dentate gyrus of Pafah1b1+/- mice that may contribute to epilepsy or cognitive impairments associated with lissencephaly.
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