For example, BCS1L founder variants restricted to Scandinavian areas cause GRACILE syndrome (growth retardation, aminoaciduria, cholestasis, iron overload, lactic acidosis and early death) [14, 15, 47], whereas others are associated with metabolic acidosis and liver failure [13, 16–20], sensorineural Björnstad syndrome [21, 22] or sensorineural hearing loss with developmental delay, hypotonia and encephalopathy [23]. Here, BCS1L is linked to GRACILE syndrome.