In
glycogen storage disease type III (GSD III), deficiency of the debranching
enzyme causes storage of an intermediate
glycogen molecule (limit
dextrin) in the affected tissues. In subtype IIIa hepatic tissue, skeletal- and cardiac muscle tissue is affected, while in subtype IIIb only hepatic tissue is affected. Cardiac storage of limit
dextrin causes a form of
cardiomyopathy, which resembles primary
hypertrophic cardiomyopathy on cardiac ultrasound. We present a 32-year-old
GSD IIIa patient with severe
left ventricular hypertrophy (LVH) first diagnosed at the age of 8 years. LVH remained stable and symptomless until the patient presented at age 25 years with increasing
dyspnea,
fatigue,
obesity, and NYHA (New York Heart Association) functional classification two out of four.
Dyspnea,
fatigue, and
obesity progressed, and at age 28 years she was severely symptomatic with NYHA classification 3+ out of 4. On echocardiogram and electrocardiogram, the LVH had progressed as well. Initially, she was rejected for
cardiac transplantation because of
severe obesity. Therefore, a 900 cal,
high protein diet providing 37% of total energy was prescribed during 4 months on which 10 kg
weight loss was achieved. However, her symptoms as well as the electrocardiographic and echocardiographic LVH indices had improved dramatically - ultimately deferring
cardiac transplantation. Thereafter, the caloric intake was increased to 1,370 cal per day, and the high
protein intake was continued providing 43% of total energy. After 3 years of follow-up, the patient remains satisfied with reasonable exercise tolerance and minor symptoms in daily life.