Bulbar muscle weakness and fatty lingual infiltration in glycogen storage disorder type IIIa.
Glycogen storage disorder type III (GSD III) is a rare autosomal recessive disorder resulting from a deficiency of glycogen debranching enzyme, critical in cytosolic glycogen degradation. GSD IIIa, the most common form of GSD III, primarily affects the liver, cardiac muscle, and skeletal muscle. Although skeletal muscle weakness occurs commonly in GSD IIIa, bulbar muscle involvement has not been previously reported. Here we present three GSD IIIa patients with clinical evidence of bulbar weakness based on instrumental assessment of lingual strength. Dysarthria and/or dysphagia, generally mild in severity, were evident in all three individuals. One patient also underwent correlative magnetic resonance imaging (MRI) which was remarkable for fatty infiltration at the base of the intrinsic tongue musculature, as well as abnormal expansion of the fibro-fatty lingual septum. Additionally, we provide supportive evidence of diffuse glycogen infiltration of the tongue at necropsy in a naturally occurring canine model of GSD IIIa. While further investigation in a larger group of patients with GSD III is needed to determine the incidence of bulbar muscle involvement in this condition and whether it occurs in GSD IIIb, clinical surveillance of lingual strength is recommended.
Department of Radiology, Duke University Medical Center, DUMC 3808 Durham, NC 27710, USA.
Jeffrey J
JJ
Horvath
Stephanie L
SL
Austin
Harrison N
HN
Jones
Elizabeth J
EJ
Drake
Laura E
LE
Case
Brian J
BJ
Soher
Mustafa R
MR
Bashir
Priya S
PS
Kishnani
D000273:Adipose Tissue / Q000378:metabolism / Q000473:pathology*; D000328:Adult; D000818:Animals; D002648:Child; D003680:Deglutition Disorders / Q000378:metabolism / Q000473:pathology; D004285:Dogs; D004401:Dysarthria / Q000378:metabolism / Q000473:pathology; D005260:Female; D006003:Glycogen / Q000378:metabolism*; D006004:Glycogen Debranching Enzyme System / Q000172:deficiency / Q000235:genetics; D006010:Glycogen Storage Disease Type III / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008875:Middle Aged; D018908:Muscle Weakness / Q000378:metabolism / Q000473:pathology*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D009154:Mutation; D014059:Tongue / Q000378:metabolism / Q000473:pathology*
D006004:Glycogen Debranching Enzyme System; D006003:Glycogen