oRGs and mitotic somal translocation - a role in development and disease.

The evolution of the human brain has been characterized by an increase in the size of the neocortex. Underlying this expansion is a significant increase in the number of neurons produced by neural stem cells during early stages of cortical development. Here we highlight recent advances in our understating of these cell populations, consisting of ventricular radial glia and outer radial glia. We highlight how gene expression studies have identified molecular signatures for radial glial cell populations and outline what has been learned about the mechanisms underlying the characteristic mode of division observed in outer radial glia cells, mitotic somal translocation. Understanding the significance of this behavior may help us explain human cortical expansion and further elucidate neurodevelopmental diseases

Control of Outer Radial Glial Stem Cell Mitosis in the Human Brain

Evolutionary expansion of the human neocortex is partially attributed to a relative abundance of neural stem cells in the fetal brain called outer radial glia (oRG). oRG cells display a characteristic division mode, mitotic somal translocation (MST), in which the soma rapidly translocates toward the cortical plate immediately prior to cytokinesis. MST may be essential for progenitor zone expansion, but the mechanism of MST is unknown, hindering exploration of its function in development and disease. Here, we show that MST requires activation of the Rho effector ROCK and nonmuscle myosin II, but not intact microtubules, centrosomal translocation into the leading process, or calcium influx. MST is independent of mitosis and distinct from interkinetic nuclear migration and saltatory migration. Our findings suggest that disrupted MST may underlie neurodevelopmental diseases affecting the Rho-ROCK-myosin pathway and provide a foundation for future exploration of the role of MST in neocortical development, evolution, and disease

Peripartum disease activity in moderately and severely disabled women with multiple sclerosis.

BackgroundThe effects of pregnancy on multiple sclerosis (MS) inflammatory activity are not well described in women with moderate to severe disabilities.ObjectiveTo quantify the peripartum annualized relapse rate (ARR) in women with MS with an Expanded Disability Status Scale (EDSS) ≥ 3.MethodsWe performed a retrospective cohort study of 85 pregnancies in 74 subjects with preconception EDSS ≥ 3. We quantified peripartum ARR and tested for risk factors predictive of peripartum relapses, postpartum brain magnetic resonance imaging activity (new T2 or gadolinium-enhancing lesions), and disability worsening.ResultsThere were 74 live births, with a 56% operative delivery rate. In subjects with relapsing-remitting MS, ARR decreased to 0.11 during the third trimester of pregnancy compared to 0.59 in the year preconception and increased to 1.22 in the 3 months postpartum. Women with a higher preconception EDSS had higher odds of postpartum relapses and clinically significant worsening of disability as compared to subjects with a lower EDSS.ConclusionsModerately to severely disabled women with MS have a lower risk of relapse during pregnancy as compared to preconception, followed by a marked increase postpartum. Further studies are needed to identify ways to reduce peripartum inflammatory activity and disability progression in women with MS with moderate to severe disability

Inflammatory Activity After Diverse Fertility Treatments: A Multicenter Analysis in the Modern Multiple Sclerosis Treatment Era

Background and objectivesPatients with multiple sclerosis (MS) may seek fertility treatment (FT)-including in vitro fertilization (IVF). Variable relapse risk after IVF has been reported in small historical cohorts, with more recent studies suggesting no change in annualized relapse rate (ARR). The objective of this study was to evaluate ARR 12 months pre-FT and 3 months post-FT in a multicenter cohort and identify factors associated with an increased risk of relapse.MethodsPatients with clinically isolated syndrome (CIS) or MS aged 18-45 years with at least 1 FT from January 1, 2010, to October 14, 2021, were retrospectively identified at 4 large academic MS centers. The exposed period of 3 months after FT was compared with the unexposed period of 12 months before FT. FTs included controlled ovarian stimulation followed by fresh embryo transfer (COS-ET), COS alone, embryo transfer (ET) alone, and oral ovulation induction (OI). The Wilcoxon signed rank test and mixed Poisson regression models with random effects were used to compare ARR pre-FT vs post-FT, with the incidence rate ratio (IRR) and 95% CI reported.ResultsOne hundred twenty-four FT cycles among 65 patients with MS (n = 56) or CIS (n = 9) were included: 61 COS-ET, 19 COS alone, 30 ET alone, and 14 OI. The mean age at FT was 36.5 ± 3.8 years, and the mean disease duration was 8.2 ± 5.0 years. Across 80 cycles with COS, only 5 relapses occurred among 4 unique patients within 3 months of treatment. The mean ARR after COS and before was not different (0.26 vs 0.25, p = 0.37), and the IRR was 0.95 (95% CI: 0.52-1.76, p = 0.88). No cycles with therapeutic disease-modifying therapies (DMTs) during COS had 3 months relapse (ARR 0 post-COS vs 0.18 pre-COS, p = 0.02, n = 34). Relapse rates did not vary by COS protocol. Among COS-ET cycles that achieved pregnancy (n = 43), ARR decreased from 0.26 to 0.09 (p = 0.04) within the first trimester of pregnancy. There were no relapses 3 months after ET alone and 1 relapse after OI.DiscussionIn this modern multicenter cohort of patients with MS undergoing diverse FTs, which included 43% on DMTs, we did not observe an elevated relapse risk after FT

De Novo Variants in the ATPase Module of MORC2 Cause a Neurodevelopmental Disorder with Growth Retardation and Variable Craniofacial Dysmorphism

MORC2 encodes an ATPase that plays a role in chromatin remodeling, DNA repair, and transcriptional regulation. Heterozygous variants in MORC2 have been reported in individuals with autosomal-dominant Charcot-Marie-Tooth disease type 2Z and spinal muscular atrophy, and the onset of symptoms ranges from infancy to the second decade of life. Here, we present a cohort of 20 individuals referred for exome sequencing who harbor pathogenic variants in the ATPase module of MORC2. Individuals presented with a similar phenotype consisting of developmental delay, intellectual disability, growth retardation, microcephaly, and variable craniofacial dysmorphism. Weakness, hyporeflexia, and electrophysiologic abnormalities suggestive of neuropathy were frequently observed but were not the predominant feature. Five of 18 individuals for whom brain imaging was available had lesions reminiscent of those observed in Leigh syndrome, and five of six individuals who had dilated eye exams had retinal pigmentary abnormalities. Functional assays revealed that these MORC2 variants result in hyperactivation of epigenetic silencing by the HUSH complex, supporting their pathogenicity. The described set of morphological, growth, developmental, and neurological findings and medical concerns expands the spectrum of genetic disorders resulting from pathogenic variants in MORC2