Expression profiling of skin fibroblast, iPSC, iPSC-derived neural progenitors, and iPSC-derived neurons from Autism Spectrum Disorder male patients and their unaffected normal male siblings

Autism spectrum disorder (ASD) is an early onset neurodevelopmental disorder, which is characterized by disturbances of brain function and behavioral deficits in core areas of impaired reciprocal socialization, impairment in communication skills, and repetitive or restrictive interests and behaviors. ASD is known to have a significant genetic risk, but the underlying genetic variation can be attributed to hundreds of genes. The molecular and pathophysiologic basis of ASD remains elusive because of its genetic heterogeneity and complexity, its high comorbidity with other diseases, and the paucity of brain tissue for study. The invasive nature of collecting primary neuronal tissue from patients might be circumvented through reprogramming peripheral cells to induced pluripotent stem cells (iPSCs), which are able to generate live neurons carrying the genetic variants of disease. This breakthrough allows us to access the cellular and molecular phenotypes of patients with intrinsic autism, that is patients without known genetic disorders or identifiable syndromes or malformations. To do this, we studied a relatively homogeneous patient population of boys with intrinsic autism by excluding patients with known genetic disease or recognizable phenotypes or syndromes, as well as those with profound mental retardation or primary seizure disorders. We generated iPSCs from patients with intrinsic autism, their unaffected male siblings and age-, and sex-matched unaffected controls. And these stem cells were subsequently differentiated into electrophysiologically active neurons. The expression profile for autistic and their unaffected siblings' iPSC-derived neurons were compared. A distinct expression profile was found between autism and sib control. The significantly differentially expressed genes (> 2-fold, FDR < 0.05) in autistic iPSC-derived neurons were significantly enriched for processes related to synaptic transmission, such as neuroactive ligand-receptor signaling and extracellular matrix interactions (FDR < 0.05), and were significantly enriched for genes previously associated with ASD (p < 0.05). Our findings suggest approaches such as iPSC-derived neurons will be an important method to obtain tissue for study that appropriately recapitulates the complex dynamics of an autistic neural cell.

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Liu X, Campanac E, Cheung HH, Ziats MN, Canterel-Thouennon L, Raygada M, Baxendale V, Pang AL, Yang L, Swedo S, Thurm A, Lee TL, Fung KP, Chan WY, Hoffman DA, Rennert OM