Autistic-like Behaviors Associated with a Novel Non-Canonical Splice-Site DDX3X Variant: A Case Report of a Rare Clinical Syndrome

A comprehensive review on DDX3X liquid phase condensation in health and neurodevelopmental disorders

DEAD-box helicases are global regulators of liquid-liquid phase separation (LLPS), a process that assembles membraneless organelles inside cells. An outstanding member of the DEAD-box family is DDX3X, a multi-functional protein that plays critical roles in RNA metabolism, including RNA transcription, splicing, nucleocytoplasmic export, and translation. The diverse functions of DDX3X result from its ability to bind and remodel RNA in an ATP-dependent manner. This capacity enables the protein to act as an RNA chaperone and an RNA helicase, regulating ribonucleoprotein complex assembly. DDX3X and its orthologs from mouse, yeast (Ded1), and C. elegans (LAF-1) can undergo LLPS, driving the formation of neuronal granules, stress granules, processing bodies or P-granules. DDX3X has been related to several human conditions, including neurodevelopmental disorders, such as intellectual disability and autism spectrum disorder. Although the research into the pathogenesis of aberrant biomolecular condensation in neurodegenerative diseases is increasing rapidly, the role of LLPS in neurodevelopmental disorders is underexplored. This review summarizes current findings relevant for DDX3X phase separation in neurodevelopment and examines how disturbances in the LLPS process can be related to neurodevelopmental disorders.

DDX3X Syndrome Behavioral Manifestations with Particular Emphasis on Psycho-Pathological Symptoms-A Review

(1) Background: Identification of typical behavioral manifestations in patients with DEAD-Box Helicase 3 X-linked gene (DDX3X) variants plays a crucial role in accurately diagnosing and managing the syndrome. The objective of this paper was to carry out a review of medical and public databases and assess the behavioral features of the DDX3X syndrome (DDX3X), with a particular focus on psycho-pathological symptoms. (2) Methods: An extensive computerized search was conducted in various databases, including PubMed, Medline Complete, Science Direct, Scopus, and Web of Science. Specific keywords and Medical Subject Headings were used to ensure the inclusion of relevant studies. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were applied to assess the methodological quality of the manuscripts. (3) Results: Only nine papers out of the 272 assessed met the inclusion criteria. These articles revealed various psycho-pathological manifestations in patients with the DDX3X syndrome. Intellectual disability (ID) or developmental disability (DD), speech delay, autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), generalized anxiety disorder (GAD), self-injurious behaviors (SIBs), sensory symptoms and sleep disturbance were demonstrated to be the most common psycho-pathological behavior manifestations. (4) Conclusions: Patients with the DDX3X syndrome manifest a wide spectrum of psycho-pathological symptoms. A comprehensive investigation of these symptoms in patients is essential for early diagnosis and effective therapy.

The variant landscape and function of DDX3X in cancer and neurodevelopmental disorders

RNA molecules rely on proteins across their life cycle. DDX3X encodes an X-linked DEAD-box RNA helicase with a Y-linked paralog, DDX3Y. DDX3X is central to the RNA life cycle and is implicated in many conditions, including cancer and the neurodevelopmental disorder DDX3X syndrome. DDX3X-linked conditions often exhibit sex differences, possibly due to differences between expression or function of the X- and Y-linked paralogs DDX3X and DDX3Y. DDX3X-related diseases have different mutational landscapes, indicating different roles of DDX3X. Understanding the role of DDX3X in normal and disease states will inform the understanding of DDX3X in disease. We review the function of DDX3X and DDX3Y, discuss how mutation type and sex bias contribute to human diseases involving DDX3X, and review possible DDX3X-targeting treatments.