Postnatal relevance of HOXA5 transcription factor in cerebellum-associated behaviors and disorders.

Hoxa5 encodes a transcription factor essential for embryonic patterning and organogenesis, with sustained expression in hindbrain precerebellar nuclei during postnatal development. Given prior evidence implicating HOXA5 in synaptogenesis and early postnatal circuit maturation, we investigated whether its inactivation during this critical developmental window contributes to neurodevelopmental disorder (NDD)-related phenotypes. Using previously generated transcriptomic data, we identified multiple deregulated genes classified as autism spectrum disorder (ASD) risk genes in the SFARI database, several of which are associated with a cerebellar phenotype in mice. We then performed a comprehensive behavioral assessment across motor, social, stereotypical, anxiety-related, and attentional domains in a postnatal inactivation mouse model (Hoxa5-cKO). Motor coordination, learning, gait, and sensorimotor functions were preserved. Social behavior assays yielded no consistent genotype-dependent effects, although results were sensitive to analytical methods and cohort variability. In contrast, Hoxa5-cKO mice exhibited increased stereotypical behaviors, including elevated scratching and marble burying, in the absence of anxiety- or locomotion-related confounds. Importantly, interpretation of social and cognitive phenotypes was impacted by well-known constraints of behavioral neuroscience. We discuss these downfalls and propose additional guidelines. Altogether, our findings indicate that postnatal Hoxa5 deficiency selectively enhances stereotyped behaviors without broadly affecting motor or social functions. The data support a model in which HOXA5 acts as a modulator of postnatal precerebellar circuit connectivity and/or function, with subtle behavioral consequences that require further research in specific genetic or environmental contexts.