The GatCAB aminoacyl-tRNA amidotransferase complex provides this function and is composed of three subunits: GATA encoded by QRSL1, GATB encoded by GATB, and GATC encoded by GATC. Patients with defects in glutaminyl mt-tRNA charging present in infancy with lethal cardiomyopathy and lactic acidosis. The gene discussed is QRSL1; the disease is lactic acidosis.