Bulbar muscle weakness and fatty lingual infiltration in glycogen storage disorder type IIIa

► We provide the first report of bulbar muscle involvement in glycogen storage disorder (GSD) IIIa. ► Three GSD IIIa patients had lingual weakness by instrumental assessment. ► One patient had correlative abnormal fatty infiltration of the tongue on MRI. ► Supportive abnormal glycogen infiltration on histopathology is seen in a canine model of GSD IIIa.