Summary Autosomal dominant mutations (S326fs328X, A322D) in the GABAA receptor α1 subunit are associated with human absence epilepsy and juvenile myoclonic epilepsy, respectively. Because these mutations substantially reduce α1 subunit protein expression in vitro, it was hypothesized that they produce epilepsy by causing α1 subunit haploinsufficiency. However, in a mixed background strain of mice, α1 subunit deletion does not reduce viability or cause visually-apparent seizures; the effects of α1 subunit deletion on EEG waveforms were not investigated. Here, we determined the effects of α1 subunit loss on viability, EEG spike-wave discharges and seizures in congenic C57BL/6J and DBA/2J mice. Deletion of α1 subunit caused strain- and sex-dependent reductions in viability. Heterozygous mice experienced EEG discharges and absence-like seizures within both background strains, and exhibited a sex-dependent effect on the discharges and viability in the C57BL/6J strain. These findings suggest that α1 subunit haploinsufficiency can produce epilepsy and may be a major mechanism by which the S326fs328X and A322D mutations cause these epilepsy syndromes.

Background: Heterozygous GABRA1 deletion causes absence epilepsy. Results: The deletion modestly decreased cortical GABA A receptor number but also reduced the rate of receptor endocytosis and thus partially compensated for the deletion by increasing the expression of different receptor isoforms. Conclusion: Heterozygous GABRA1 deletion caused novel alterations in cortical GABA A receptor expression and physiology. Significance: These findings reveal mechanisms of cortical disinhibition in absence epilepsy.

The GABAA receptor (GABAAR) α1 subunit mutation, A322D, causes autosomal dominant juvenile myoclonic epilepsy (JME). Previous in vitro studies demonstrated that A322D elicits α1(A322D) protein degradation and that the residual mutant protein causes a dominant-negative effect on wild type GABAARs. Here, we determined the effects of heterozygous A322D knockin (Hetα1AD) and deletion (Hetα1KO) on seizures, GABAAR expression, and motor cortex (M1) miniature inhibitory postsynaptic currents (mIPSCs) at two developmental time-points, P35 and P120. Both Hetα1AD and Hetα1KO mice experience absence seizures at P35 that persist at P120, but have substantially more frequent spontaneous and evoked polyspike wave discharges and myoclonic seizures at P120. Both mutant mice have increased total and synaptic α3 subunit expression at both time-points and decreased α1 subunit expression at P35, but not P120. There are proportional reductions in α3, β2, and γ2 subunit expression between P35 and P120 in wild type and mutant mice. In M1, mutants have decreased mIPSC peak amplitudes and prolonged decay constants compared with wild type, and the Hetα1AD mice have reduced mIPSC frequency and smaller amplitudes than Hetα1KO mice. Wild type and mutants exhibit proportional increases in mIPSC amplitudes between P35 and P120. We conclude that Hetα1KO and Hetα1AD mice model the JME subsyndrome, childhood absence epilepsy persisting and evolving into JME. Both mutants alter GABAAR composition and motor cortex physiology in a manner expected to increase neuronal synchrony and excitability to produce seizures. However, developmental changes in M1 GABAARs do not explain the worsened phenotype at P120 in mutant mice.

Individuals with autosomal dominant juvenile myoclonic epilepsy are heterozygous for a GABA A receptor ␣1 subunit mutation (␣1A322D). GABA A receptor ␣␤␥ subunits are arranged around the pore in a ␤-␣-␤-␣-␥ sequence (counterclockwise from the synaptic cleft). Therefore, each ␣1 subunit has different adjacent subunits, and heterozygous expression of ␣1(A322D), ␤, and ␥ subunits could produce receptors with four different subunit arrangements:Expression of a 1:1 mixture of wild-type and ␣1(A322D) subunits with ␤2S and ␥2S subunits (heterozygous transfection) produced smaller currents than wild type and much larger currents than homozygous mutant transfections. Western blot and biotinylation assays demonstrated that the amount of total and surface ␣1 subunit from heterozygous transfections was also intermediate between those of wild-type and homozygous mutant transfections. ␣1(A322D) mutations were then made in covalently tethered triplet (␥2S-␤2S-␣1) and tandem (␤2S-␣1) concatamers to target selectively ␣1(A322D) to each of the asymmetric ␣1 subunits. Coexpression of mutant and wild-type concatamers resulted in expression of either Het ␤␣␤ or Het ␤␣␥ receptors. Het ␤␣␤ currents were smaller than wild type and much larger than Het ␤␣␥ and homozygous currents. Furthermore, Het ␤␣␤ transfections contained less ␤-␣ concatamer than wild type but more than both Het ␤␣␥ and homozygous mutant transfections. Thus, whole-cell currents and protein expression of heterozygous ␣1(A322D)␤2S␥2S receptors depended on the position of the mutant ␣1 subunit, and GABA A receptor currents in heterozygous individuals likely result primarily from wild-type and Het ␤␣␤ receptors with little contribution from Het ␤␣␥ and homozygous receptors.

Objective:In this study we implemented the “flipped classroom” model to enhance active learning in medical students taking neurosciences module at Aga Khan University, Karachi.Methods:Ninety eight undergraduate medical students participated in this study. The study was conducted from January till March 2017. Study material was provided to students in form of video lecture and reading material for the non-face to face sitting, while face to face time was spent on activities such as case solving, group discussions, and quizzes to consolidate learning under the supervision of faculty. To ensure deeper learning, we used pre- and post-class quizzes, work sheets and blog posts for each session. Student feedback was recorded via a likert scale survey.Results:Eighty four percent students gave positive responses towards utility of flipped classroom in terms of being highly interactive, thought provoking and activity lead learning. Seventy five percent of the class completed the pre-session preparation. Students reported that their queries and misconceptions were cleared in a much better way in the face-to-face session as compared to the traditional setting (4.09 ±1.04).Conclusion:Flipped classroom(FCR) teaching and learning pedagogy is an effective way of enhancing student engagement and active learning. Thus, this pedagogy can be used as an effective tool in medical schools.