Principal Investigator: Prof Antonio Adamo

Poster Presenter: Veronica Astro



Sex chromosome overdosage impairs both morphological and electrophysiological properties of iPSC-derived neurons and brain organoids



Veronica Astro, Lorena Cortes, Kelly Cardona-Londono, Rawan Alghamdi, Antonio Adamo*

Sex chromosome overdosage in Klinefelter Syndrome (KS; 47,XXY) and high-grade sex-chromosome aneuploidies (HG-SCAs; 48,XXXY and 49,XXXXY) manifests in a range of clinical phenotypes, including structural brain abnormalities, cognitive impairments, and deficits in motor, speech, and language capabilities. The extent of these neurological defects is directly proportional to the surplus of X chromosomes. Notwithstanding, the absence of murine models coupled with limited in vitro disease-modeling has created a considerable gap in our understanding of the molecular mechanisms underpinning KS and SCAs. We have pioneered a collection of patient-derived induced pluripotent stem cells (iPSCs) with karyotypes 46,XY, 47,XXY, 48,XXXY, and 49,XXXXY. This paradigmatic cohort includes individuals from diverse geographical locations such as Saudi Arabia, Europe, and North America, thus ensuring a representation of varied genomic backgrounds. Utilizing these iPSCs, we investigated the impact of sex-chromosome aneuploidies during early neurodevelopment using a disease-modeling approach based on 2D neuronal cultures and cortical brain organoids. Through an array of morphological and functional assays, we elucidated that sex chromosome overdosage detrimentally alters the structural and functional properties of iPSC-derived 2D neurons and cortical organoids in a dose-dependent manner. Furthermore, we performed a comprehensive transcriptomic analysis of both 2D and 3D neuronal derivatives to discern the influence of supernumerary X chromosomes on genomic regulation, thereby narrowing down potential X-linked genes contributing to the observed neurodevelopmental abnormalities in KS and HGA SCA patients. Our data point to the overdosage of escape genes within the pseudoautosomal region 1 (PAR1) of the X and Y chromosomes as the direct triggers of the neurodevelopmental disparities observed in KS and HG-SCA patients. In conclusion, our research provides pivotal insights into the consequences of supernumerary X chromosomes at both molecular and cellular levels during early development and establishes a robust cellular model for probing X inactivation dynamics during prolonged stem cell differentiation in vitro. Prospectively, our exhaustive collection of iPSC-derived brain organoids from typically developing males, KS and HG-SCA subjects represents an optimal cellular scaffold to deepen our comprehension of the roles of X-linked genes in neurogenesis and for potential pharmacological applications.