Case report: a 10 month-old infant was admitted to hospital for stunted growth (-4SD). The diagnosis of glycogen storage disease (GSD) was suspected. RBC phosphorylase kinase activity was found to be normal. Liver needle biopsy confirmed the diagnosis of GSD and excluded GSD type I. 13C NMR was then performed. GSD type VI was later proved by the enzymatic assay.Methods: Ten minutes 1H decoupled 13C spectra of calf muscles and liver were obtained at 2T. Spectra were acquired with a 160° pulse at the coil center repeated every 200ms and with a 40ms acquisition time. The glycogen content was evaluated from the area of the glycogen C1 peak at 100.5 ppm. It was normalized to the area of the creatine peak at 157 ppm. 7 normal subjects and 11 patients suffering from GSD (3 type la, 2 type III, 4 type V, 1 type VI and 1 type VII) were studied.Results: The muscular glycogen/creatine ratio, R, was 2.0±0.7 in normal subjects and 2.1 in GSD type I. It was 13±1.7 in type V, 13.5 and 15 in type III, and 11.2 in type VII. In our patient, R was found to be 2.0. Semi quantitative (no internal reference for liver) evaluation of hepatic glycogen indicated high levels in the liver of our patient, as observed in GSD affecting the liver (types I, II, and VI).Conclusions: NMR allowed to exclude type III and strongly argued for type VI. Therefore, in vivo 13C NMR is able to distinguish GSD affecting the muscle from those not affecting it and also appears to detect abnormal hepatic glycogen content.
Read full abstract