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Noncompaction myocardium in association with type Ib glycogen storage disease

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Abstract

Noncompaction myocardium is a rare disorder assumed to occur as an arrest of the compaction process during the normal development of the heart. Left ventricular noncompaction has been reported to be associated with a variety of cardiac and extracardiac, especially neuromuscular abnormalities. Moreover, it has been suggested that metabolic alterations could be responsible for the noncompaction. However, no association of noncompaction myocardium with type Ib glycogen storage disease (GSD) has been reported so far. Type Ib GSD is due to a defect of a transmembrane protein which results, similar to type Ia GSD, in hypoglycemia, a markedly enlarged liver and, additionally, in neutropenia, recurrent infections, and inflammatory bowel disease. Until now, no muscular or cardiac involvement has been described in type Ib GSD patients. The present case represents the first report of a noncompaction myocardium in a child with type Ib GSD who died of sudden clinical deterioration at the age of four.

Introduction

Noncompaction myocardium is a condition in which the myocardium is not compacted, either due to an arrest of the compaction process during the development of the heart, or it may develop postnatally in association with cardiac or extracardiac abnormalities. The etiology of this remains unclear [14]. Apart from associations with cardiac heart anomalies, noncompaction myocardium has been linked to a variety of extracardiac, especially neuromuscular disorders [8]. Recently, it has been suggested that metabolic abnormalities could be responsible for the noncompaction [7]. The clinical presentation of noncompaction cardiomyopathy is characterized by a high prevalence of heart failure and thromboembolic events, as well as by cardiac arrhythmias [8]. Despite the use of diagnostic tools such as echocardiography and magnetic resonance imaging, the diagnosis can often only be established at autopsy or following heart transplantation [19]. Here, we report for the first time the combination of a noncompaction myocardium with type Ib glycogen storage disease (GSD Ib) in a 4-year-old boy, who died of an unexpected cardiac arrest after repeated infections.

Section snippets

Clinical history

We report the case of a young patient who was frequently treated in the pediatric clinic of our hospital for a GSD Ib, confirmed by molecular diagnostics at the age of 6 months. The clinical course was complicated by perinatal cerebral infarction and subsequent therapy-resistant focal epilepsy treated by partial neurosurgical resection of the left temporo-occipital lobe and anticonvulsant drug therapy (sultiam, oxcarbazepine). Heterozygous factor V Leiden mutation and latent hypothyroidism were

Materials and methods

Autopsy was performed and tissue specimens were taken from all parenchymal organs. Liver tissue specimens were stained for H&E, D-PAS, PAS, Fe, and Gomorri's trichrome stain; Heart tissue specimens were stained for H&E, EvG, and Masson's trichrome. Sequencing analysis of the G6PC3 gene was performed as previously described [1].

Results

Autopsy revealed an eutrophic 4-year-old boy with typical morphological features of GSD Ib with a massively enlarged liver (liver weight: 2280 g). Liver histology showed typical PAS-positive inclusions of hepatocytes, as well as sharply defined mixed-vesicular vacuoles in the cytoplasm, indicating simultaneous accumulation of glycogen and neutral lipid, consistent with GSD Ib (Fig. 2). The gut showed features of GSD Ib-associated inflammatory bowel disease. The heart weighed 155 g. Both the left

Discussion

We report on the combination of two exceedingly rare diseases in one patient: type Ib glycogen storage disease and noncompaction cardiomyopathy. In GSD Ib, a transmembrane transport protein, present in many organs and active in neutrophils and monocytes, is defective [11]. This glucose-6-phosphatase transporter (G6PT) is a single copy gene consisting of 9 exons, spanning approximately 5.3 kb of DNA at chromosome 11q23. To date, a minimum of 69 separate G6PT mutations have been identified in GSD

Acknowledgments

We wish to thank Ms. Andrea Hain and Mr. John Moyers for their excellent technical assistance.

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