Factors associated with malnutrition among under five children in Bangladesh: a multivariate analysis.

Autism spectrum disorders (ASD) comprise a complex neurodevelopmental condition that is characterized by difficulties in social cognition and communication, repetitive behaviours and hypersensitivity to external stimuli []. These core symptoms are associated with several comorbidities that may contribute to the high variability of ASD symptoms [–]. Post-mortem studies [] support a long-standing hypothesis that links ASD and other neurodevelopmental disorders (NDDs) with an imbalance between excitation and inhibition (E/I imbalance) [, ], whereby interneurons regulate cortical circuitry through their inhibitory effects. While research into NDDs has mostly focused on altered neuronal connectivity and circuitry, there is increasing evidence that NDD symptoms can originate from brain malformations occurring in the second trimester of foetal development [–]. In this period, neural stem cells generate excitatory glutamatergic projection neurons and inhibitory GABAergic interneurons in the dorsal and ventral telencephalon, respectively. Interneurons, in particular, form an enormous variety of cell types that is critical for the proper functioning of cortical circuitry. The specification of this interneuron diversity is under the control of Sonic hedgehog (SHH) signalling and a cascade of transcription factors []. After their birth, projection neurons migrate radially out of the germinal zones to form the cortical layers in an inside-out manner, while interneurons undergo complex tangential migrations from the ventral telencephalon to their target area in the cortex where they mature and integrate into cortical circuits []. Primary cilia are cellular antennas present on most cells including neural progenitors and many neurons and act as signalling hubs in development and tissue homeostasis. Defects in the function and/or structure of primary cilia underlie a group of syndromes commonly referred to as ciliopathies [] that are characterized by pleiotropic clinical features. Many ciliopathy patients display severe neurological symptoms, most commonly intellectual disability (ID) and ASD []. In turn, a cell-based high-throughput screen indicated that diverse neuropsychiatric risk genes converge on primary cilia []. This idea is further corroborated by recent findings that several monogenetic neurodevelopmental syndromes, including Fragile X and Rett syndromes, result in altered ciliary structure and signalling [–], but the mechanisms how ciliary impairments contribute to NDD pathogenesis remain largely unexplored. To date, the most compelling evidence for ciliary roles in ASD aetiology stems from the identification of autism specific mutations in several ciliary genes [–]. One of these genes, , encodes a centrosomal protein located at the basal body and in the ciliary axoneme. It is essential for the transport of Tubulin Tyrosine Ligase Like 6 (TTLL6) into the cilium and hence tubulin polyglutamylation []. Homozygous null mutations cause Joubert Syndrome (JS) [], a genetically and phenotypically heterogeneous syndrome [] associated with ID and ASD in 40% of JS patients []. In addition, heterozygous missense mutations have been identified in familial and sporadic forms of ASD [, ] but the effects of these mutations on mammalian brain development have not been explored. Here, we report our findings on human cortical organoids carrying the R242H ASD mutation []. This mutation did not interfere with CEP41’s ciliary localisation but cilia were shorter and had lower levels of tubulin polyglutamylation indicative of altered cilia stability and signalling. Moreover, scRNA-seq analyses revealed that the mutation caused an augmented formation of upper layer cortical neurons. In interneurons and their progenitors, the altered expression of several key transcription factors in interneuron development coincided with changes in interneuron differentiation. Taken together, these results indicate that the combined effects of the ASD-linked mutation on the development of projection neurons and interneurons may contribute to ASD pathogenesis.