Systemic Progression of Type IV Glycogen Storage Disease After Liver Transplantation

Abstract

Glycogen storage disease type IV (GSD IV) is a rare autosomal recessive disorder caused by a deficiency of glycogen branching enzyme (GBE), which results in the formation of an amylopectin-like polysaccharide characterized by fewer branching points, more α1- to 4-linked glucose units, and longer outer chains. This abnormal, insoluble glycogen accumulates in liver, heart, muscle, nervous system, and skin. GSD IV is a heterogeneous disorder in terms of tissue involvement, age at onset, and clinical presentation. In the classical hepatic form, patients present within the first months of life with hepatosplenomegaly and failure to thrive followed by progressive liver cirrhosis with portal hypertension and liver failure leading to death by 5 years of age. The only effective therapeutic option for these patients is liver transplantation (LT). A total of 18 patients who underwent LT for GSD IV have been reported (1). A major concern for these patients is the risk of progression of the disease in other organs such as heart, muscle, or nervous system. A majority of patients who had LT for GSD IV did not have any cardiac or neuromuscular complication during the follow-up (2). Moreover, a diminution of cardiac amylopectin-like deposits has been observed for 1 patient, attributed to microchimerism (3). However, 2 children had a progressive fatal cardiac failure after LT, attributed to massive amylopectin-like deposits in cardiac muscle (4,5). We present the experience of our center, involving 2 children who underwent LT for GSD IV and died 6.3 years and 1 year after the transplant because of extrahepatic progression of the disease with amylopectin-like deposits in several tissues, especially in the heart. CASE REPORTS Case 1 A 9-month-old boy presented with hepatosplenomegaly, developmental delay, and liver failure. Abdominal ultrasound with Doppler showed enlarged liver and spleen with signs of portal hypertension. Liver biopsies confirmed the presence of cirrhosis and revealed cytoplasmic inclusions composed of periodic acid-Schiff (PAS)–positive, diastase-resistant material identified as amylopectin-like and consistent with the diagnosis of GSD IV. The patient underwent LT 2 months later and received cyclosporine, azathioprine, and prednisone as immunosuppressive therapy. Immediately after LT, the echocardiogram showed normal myocardial function. The early posttransplant course was marked by a mild rejection and cytomegalovirus infection, respectively, treated with antilymphocyte immunoglobulins and gancyclovir. The child did then extremely well with normal growth, development, and liver function tests until 32 months after LT. He then presented with pneumonia and pleural effusion attributed to a mycoplasma infection. He was found to have a cervical synovitis and left ventricular hypertrophy on cardiac ultrasound. The following years were marked by several complications. Because of abnormal liver function tests and a slight dilatation of the left intrahepatic bile duct on ultrasound, a liver biopsy was performed, showing portal fibrosis and infiltration by macrophages filled with amylopectin-like material, confirmed by electron microscopy (Fig. 1A). The progressive obstruction of intra- and extrahepatic bile ducts, with sclerosing cholangitis-like picture on cholangiogram, led initially to a surgical revision of the choledocojejunostomy and eventually to the construction of a hepaticogastrostomy 45 months after LT. Pathology revealed a bile duct infiltration with amylopectin-filled macrophages (Fig. 1B). After biliogastric diversion, liver function remained stable with liver enzymes less than twice the normal range (2N), bilirubin around twice that of normal, and elevated γ-glutamyl transferase and alkaline phosphatase. Liver synthetic function was normal.FIGURE 1: (A) Liver biopsy specimen from patient 1. Electron microscopy (original magnification ×12,000): amylopectin-filled vacuoles in macrophages (arrow). (B) Common bile duct from patient 1 after hepaticogastrostomy (original magnification ×10). Infiltration of bile duct by macrophages with Periodic acid-Schiff–positive, diastase-resistant contents (arrow). (C) Myocardial biopsy from patient 1 (original magnification ×25). Presence of amylopectin-like material (Periodic acid-Schiff–positive diastase resistant: arrow) in myocardial fibers.Thirty-nine months after LT, evidence of extrahepatic progression of GSD appeared as a polyserositis; inflammatory cells filled with amylopectin-like inclusions were found in pleural and pericardial effusion. In addition, he developed a bilateral mastoid destruction causing persistent otorrhea and subsequently soft tissue swellings in the skin and in the mouth. Bilateral mastoidectomy and biopsies of soft tissue lesions revealed presence of macrophages filled with amylopectin-like material. Fifty months after LT, the patient developed heart failure with pulmonary edema. Cardiac ultrasound confirmed a decreased contractility with shortening fraction of 20%. The myocardial biopsy showed myocardial fibrosis, macrophages filled with amylopectin-like material, and infiltration of myocardial cells with this same amylopectin. Despite treatment with digoxin and diuretics his cardiomyopathy progressed. He was listed for heart transplant but his cardiac condition worsened, complicated with arrhythmia. He died 76 months after LT, at 7.3 years of age, in the context of terminal heart failure and Gram-positive bacterial sepsis. At autopsy, the cause of death was considered to be heart failure with severe fibrosis of the heart, especially of the left ventricule, and its consequences on other organs including pulmonary alveolar edema, peripheral edema, hepatic centrolobular damage, and the beginning of acute tubular necrosis. Histologically, there was an extensive fibrosis of the heart with hypertrophy of the residual myocardic fibers because of the infiltration with PAS-positive, diastase-resistant inclusions (Fig. 1C). Electron microscopy confirmed a massive infiltration of myocardial fibers with amylopectin-like material. Accumulation of amylopectin inclusions was found in skeletal muscle, and central and peripheral nervous system cells. Liver, spleen, lung, parathyroids, adrenal medulla, thymus, lymph nodes, bladder wall, GI mucosa, eccrine glands of the skin, inner ear, and bone marrow were infiltrated with macrophages filled with amylopectin-like inclusions. Case 2 The second patient, a 6-month-old boy, was referred for massive hepatomegaly with abnormal liver function tests. This patient was previously hospitalized when he was 2.5 months old for osteomyelitis of the elbow, which had a favorable outcome under antibiotics. On liver biopsy, there was a moderate fibrosis and PAS-positive and diastase-resistant cytoplasmic inclusions of the hepatocytes, suggestive of amylopectin-like material. The GBE enzymatic activity was extremely low in the liver (0 U for patient vs 1300 ± 390 for control) and low on fibroblasts (434 U vs 1300 ± 390). As a result of our previous experience, during the pretransplant evaluation the patient underwent a cardiac and muscular assessment. The electrocardiogram and echocardiogram were normal showing no hypertrophy and a normal contractility. A cardiac catheterisation confirmed a normal systolic function; a cardiac biopsy was performed at the same time revealing a cardiomyopathy with amylopectin-like deposits in 70% to 90% of cardiomyocytes. The neurologic assessment revealed generalized hypotonia without any evidence of central nervous system involvment. The electromyogram was normal, and muscular biopsy revealed a mild accumulation of amylopectin-like material in some muscular fibers. The patient underwent an LT when he was 11 months old because of progressive liver failure. In the early postoperative period, he developed a moderate hepatic rejection treated by adding mycophenolate mofetil to tacrolimus and prednisone, cytomegalovirus infection, and persistent pulmonary atelectasis with pulmonary insufficiency requiring oxygen. He was discharged 7 weeks after liver transplant. On follow-up, liver function tests normalized. A pamidronate treatment was started 6 months after LT because of severe osteopenia that was responsible for several fractures and neck pain. Two weeks later, he was hospitalized for fever with pulmonary distress, oxygen dependency, and pulmonary infiltrates and marked cardiomegaly on chest radiograph. An ultrasound showed normal cardiac function, a moderate left ventricular hypertrophy, and a mild pericardial effusion. Because of the myocardial infiltration, digoxin was initiated. Despite antibiotics, antifungal, antiviral, and diuretic therapy, patient status worsened and he required mechanical ventilation. A lung biopsy was performed 2 weeks after admission. It showed a marked interstitial and bronchoalveolar infiltration with amylopectin-like laden macrophages and pleural thickening. This pulmonary manifestation of glycogenosis was treated with steroids, allowing the discontinuation of ventilation after 1 week. Ten months after LT the patient presented with a pneumothorax that required a chest tube. Two months later, he was again admitted because of heart failure with a left ventricular dilatation and hypertrophy, an ejection rate of 44%, and a shortening fraction of 16%. Diuretics and captopril were added. The patient died 2 days after discharge. Postmortem specimens of heart, lung, and muscle were obtained. On myocardial biopsy, almost all of the cardiomyocytes contained PAS-positive, diastase-resistant inclusions, occupying more than 50% of the myofibrillar space (Fig. 2A, B). Amylopectin-filled macrophages were found in the alveolae, the pleura, and the septa (Fig. 2C). Thirty percent of fibers in the abdominal striated muscle and 50% of fibers in the diaphragmatic muscle also contained amylopectin-like inclusions.FIGURE 2: (A) Postmortem myocardial biopsies from patient 2 (original magnification ×40); transverse and (B) longitudinal sections. Amylopectin deposits (Periodic acid-Schiff–positive diastase resistant: arrow) in myocardial cells. (C) Postmortem lung biopsy from patient 2 (original magnification ×20): interstitial and bronchoalveolar infiltration with amylopectin-filled macrophages (Periodic acid-Schiff–positive diastase resistant: arrow).DISCUSSION Liver transplant is the only therapeutic option for the classical form of GSD IV characterized by early liver failure. Because amylopectin-like material is not soluble and GBE is present in other tissues, including the heart or the muscles, extrahepatic progression of the disease is a potential risk for these patients. Our experience in LT for GSD IV is based on these 2 patients who had a fatal course because of extrahepatic posttransplant progression of the disease. Two patients with GSD IV have been previously reported to have died of cardiomyopathy with amylopectin-like material deposits in myocytes, 9 months and 2.5 years after LT (4,5). These observations are different from those described for most patients who have undergone LT for GSD IV. Indeed, of the 17 patients who had a LT for GSD IV, 11 did not have any sign of skeletal myopathy or cardiomyopathy during follow-up, as long as 13.5 years (1). One died of cardiomyopathy, 1 had hypotonia and arthrogryposis, and 4 died of causes independent of GSD IV. Moreover, no progression and even a resorption of cardiac amylopectin-like deposits were observed for 2 patients, 11 and 14 months after LT (6). This phenomenon has been attributed to the migration of donor cells from the graft with microchimerism transferring enzyme activity to the recipient's tissue cells (3). The reasons for such a different outcome are not clear. Of the 4 patients who died of cardiac progression of the disease after LT, none had a clinical evidence of pretransplant cardiac dysfunction and the 3 who were tested with echocardiogram or cardiac catheterization had a normal cardiac function before the LT. The presence of amylopectin-like deposits in most of the cardiomyocytes of 1 of our patients could have been a predictor of a poor outcome. However, of the 7 patients described by Selby et al (6), 2 had cardiac amylopectin-like deposits only a few weeks after the LT, which was probably already present before the procedure, and none had a progressive cardiomyopathy. Moreover, 1 patient with a clinical favorable outcome had 13% of the myocardium occupied by amylopectin compared with only 7.5% for a patient reported to have died of cardiac failure. Although the cause of death for our patients was heart failure with a massive accumulation of amylopectin-like material and reduced myofibrils in cardiomyocytes, other organs were also found to be infiltrated. Amylopectin-like deposits were found not only in muscular cells but also in central nervous system cells as previously described (5). Moreover, the autopsy of the first patient showed amylopectin-laden macrophages infiltrated in almost all of the organs or tissues. This same infiltration was found on the lung biopsy for patient 2, and because any other cause was ruled out, it has been considered responsible for the respiratory failure. These cases illustrate the systemic nature of GSD IV and the uncertainty about their prognosis even in the event of a subsequent heart transplant. Our second patient developed severe respiratory distress only 2 weeks after pamidronate injection. First infusions of this treatment have been reported to sometimes trigger respiratory distress in patients with osteogenesis imperfecta and preexisting respiratory compromise (7). Moreover, aminobisphosphonates have been shown to promote inflammatory reactions composed particularly of macrophages, facilitate transendothelial migration of macrophages, and increase adhesion molecule expression on mononuclear cells (8,9). This treatment could have contributed to triggering or increasing the pulmonary inflammation for our patient. GSD IV is characterized by a remarkable heterogeneity in the clinical and biochemical expression of the disease. Indeed, mutations in the same GBE gene are responsible for presentations as different as the classical hepatic form, hydrops fetalis with arthrogryposis, severe neuromuscular congenital form, and an adult neuromyopathy named polyglucosan body disease (10). The human GBE is a 702-amino acid protein encoded by a 2106-bp sequence. More than 20 different mutations have been reported in GSD IV (8,9). The clinical presentation does not appear to predict the clinical course of the hepatic form of GSD IV. Possibly, differences in genotype may explain the different prognoses; however, the genotype-phenotype correlation remains unclear in GSD IV. The same genetic defect may be present in unrelated patients with completely different presentations (10,11). Three patients with the classical hepatic form of GSD IV were genotyped: 2 underwent LT and the third died of liver failure before 4 years of age. Five different mutations were described: R524Q, D13fsX12, R515C, F257L, and R524X (11,12). Unfortunately, the posttransplant outcome of these 2 transplanted patients is not known. The genotype of the 2 patients reported in the literature, who died of cardiomyopathy, was not reported. For the first patient of this report, the genotype is not known. The second patient was found to be a compound heterozygote with mutations F535C and exon15delA. To our knowledge, these are 2 novel mutations for GSD IV. It may be useful to systematically genotype patients with GSD IV who are about to receive LT to determine whether genotype is predictive of the postliver transplant course. Our observations show that LT may not alter the extrahepatic progression of GSD IV, particularly cardiomyopathy that has been implicated to date in the death of 4 patients. Functional evaluation of the heart does not provide any predicting factor in this situation. Because LT remains the only therapeutic option and no predictive factor for poor outcome has yet been established, we think that this procedure can reasonably be offered to these patients. Myocardial biopsy remains a potential predictor of heart functional outcome in the shortterm or midterm; however, the threshold of amylopectin infiltration associated with a bad prognosis needs to be defined. Acknowledgment We acknowledge Dr Victor Kotka for providing Figures 1 and 2.