RBM8A

Phenotypes

Mouse phenotype:

Prx1-Cre conditional Rbm8a knockout: shorter limb bones across developmental timepoints, delayed ossification, altered cranial morphogenesis, impaired motor function, reduced brain size, reduced SOX9 and increased IHH in primary ossification center, downregulation of Hedgehog targets (Gli3, Hhip).

Mouse ciliopathy phenotype:

Conditional Rbm8a knockout phenotype includes selective Hedgehog pathway attenuation and skeletal abnormalities consistent with ciliopathy spectrum (Mott et al. 2026). No direct cilium morphology defect reported.

Subcellular localization

cilia associated gene, nucleus

Functional category

• mRNA processing
• Exon junction complex
• Hedgehog signalling (mouse model)

Function

RNA-binding motif protein 8A is a core component of the exon junction complex (EJC) involved in post-transcriptional mRNA regulation. Compound heterozygous mutations cause Thrombocytopenia-Absent Radius (TAR) syndrome (OMIM #274000). In mouse Prx1-Cre conditional knockout (limb bud and craniofacial mesenchyme), RBM8A deficiency causes shorter limb bones, delayed ossification, altered cranial morphogenesis, reduced brain size, and disrupted Hedgehog signalling (Mott et al. 2026). RIP-seq shows RBM8A preferentially associates with long, exon-rich transcripts enriched in primary cilia and developmental signalling pathways. Earlier zebrafish work (Sztal/Panayiotou 2023) implicates rbm8a in non-canonical Wnt/PCP signalling. *Note: ciliary mechanism is supported by mouse and zebrafish evidence only; no direct evidence yet of ciliary defects in human patient cells.*