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Further Delineation of Duplications of ARX Locus Detected in Male Patients with Varying Degrees of Intellectual Disability

Authors :
Loredana Poeta
Michela Malacarne
Agnese Padula
Denise Drongitis
Lucia Verrillo
Maria Brigida Lioi
Andrea M. Chiariello
Simona Bianco
Mario Nicodemi
Maria Piccione
Emanuela Salzano
Domenico Coviello
Maria Giuseppina Miano
Poeta L.
Malacarne M.
Padula A.
Drongitis D.
Verrillo L.
Lioi M.B.
Chiariello A.M.
Bianco S.
Nicodemi M.
Piccione M.
Salzano E.
Coviello D.
Miano M.G.
Poeta, L.
Malacarne, M.
Padula, A.
Drongitis, D.
Verrillo, L.
Lioi, M. B.
Chiariello, A. M.
Bianco, S.
Nicodemi, M.
Piccione, M.
Salzano, E.
Coviello, D.
Miano, M. G.
Publication Year :
2022
Publisher :
MDPI, 2022.

Abstract

The X-linked gene encoding aristaless-related homeobox (ARX) is a bi-functional transcription factor capable of activating or repressing gene transcription, whose mutations have been found in a wide spectrum of neurodevelopmental disorders (NDDs); these include cortical malformations, paediatric epilepsy, intellectual disability (ID) and autism. In addition to point mutations, duplications of the ARX locus have been detected in male patients with ID. These rearrangements include telencephalon ultraconserved enhancers, whose structural alterations can interfere with the control of ARX expression in the developing brain. Here, we review the structural features of 15 gain copy-number variants (CNVs) of the ARX locus found in patients presenting wide-ranging phenotypic variations including ID, speech delay, hypotonia and psychiatric abnormalities. We also report on a further novel Xp21.3 duplication detected in a male patient with moderate ID and carrying a fully duplicated copy of the ARX locus and the ultraconserved enhancers. As consequences of this rearrangement, the patient-derived lymphoblastoid cell line shows abnormal activity of the ARX-KDM5C-SYN1 regulatory axis. Moreover, the three-dimensional (3D) structure of the Arx locus, both in mouse embryonic stem cells and cortical neurons, provides new insight for the functional consequences of ARX duplications. Finally, by comparing the clinical features of the 16 CNVs affecting the ARX locus, we conclude that—depending on the involvement of tissue-specific enhancers—the ARX duplications are ID-associated risk CNVs with variable expressivity and penetrance.

Details

Language :
English
Database :
OpenAIRE
Accession number :
edsair.doi.dedup.....921f789640e696dd39a97e136dc09b59