The principal clinical manifestations of IARS1 deficiency were intrauterine growth retardation (13/13), failure to thrive (13/14), feeding difficulties (10/14), elevated aminotransferases (11/14), cholestasis (8/14), acute liver failure (7/14), hepatomegaly (7/14), hypoalbuminemia (10/14), coagulation abnormalities (8/14), microcephaly (11/14), neurodevelopmental delay (10/14), hypotonia (9/14), impaired intellectual development (6/7), recurrent infections (9/14), special facial appearance (8/14), zinc deficiency (4/7), and pulmonary alveolar proteinosis (3/14). The gene discussed is IARS1; the disease is microcephaly.