SAR1B and chylomicron retention disease: For example, deciphering chylomicron retention disease (CRD) afforded new insight into the crucial functions of SAR1B GTPase, the defects of which lead to severe fat malabsorption, hypocholesterolemia, extensive steatorrhea, and significant failure to thrive in children (7, 8) with developmental abnormalities in various organs (9).