EFL1 encodes a GTPase that plays a critical role in ribosome biogenesis and maturation 1. EFL1 functions in concert with the Shwachman-Bodian-Diamond syndrome (SBDS) protein to catalyze the release of eukaryotic initiation factor 6 (eIF6) from 60S ribosomal subunits, which is the final step required for ribosome maturation and translation competence 12. The protein exhibits GTPase activity that is stimulated by SBDS through direct interaction mediated by EFL1's intrinsically disordered insertion domain and SBDS domains II-III 1. EFL1 is evolutionarily related to elongation factors EF-2 and EF-G, having originated through gene duplication from EF-2 proteins and subsequently specialized in ribosome maturation 3. Functionally, EFL1 shows species-specificity and possible co-evolution with SBDS and the 60S ribosomal subunit 3. Disease-associated mutations in EFL1 cause Shwachman-Diamond syndrome type 2, a ribosomopathy characterized by neutropenia, pancreatic insufficiency, and increased leukemia risk 45. These mutations impair mature ribosome formation and compromise protein synthesis 5. In SDS patients, chromosome 15 aberrations that increase EFL1 gene dosage can provide somatic genetic rescue 6.