90% of patients have biallelic mutations in the SBDS gene (encoding a 250 amino acid protein)

SBDS protein is a gatekeeper performing quality control for ribosome formation

SBDS protein couples the final step in cytoplasmic maturation of the large (60S) ribosomal subunit to a quality control assessment of the structural and functional integrity of the nascent particle.

SBDS functions as a cofactor for elongation factor-like GTPase 1 (EFL1) in removing the anti-association factor eIF6 from the subunit joining face of the 60S ribosomal subunit