The pattern of involvement of adult-onset acid maltase deficiency at autopsy

GAA deficiency disrupts distal airway cells in Pompe disease

Pompe disease is an autosomal recessive glycogen storage disease caused by mutations in the gene that encodes acid alpha-glucosidase (GAA)-an enzyme responsible for hydrolyzing lysosomal glycogen. GAA deficiency results in systemic lysosomal glycogen accumulation and cellular disruption. Glycogen accumulation in skeletal muscles, motor neurons, and airway smooth muscle cells is known to contribute to respiratory insufficiency in Pompe disease. However, the impact of GAA deficiency on the distal alveolar type 1 and type 2 cells (AT1 and AT2) has not been evaluated. AT1 cells rely on lysosomes for cellular homeostasis so that they can maintain a thin barrier for gas exchange, whereas AT2 cells depend on lysosome-like structures (lamellar bodies) for surfactant production. Using a mouse model of Pompe disease, the Gaa-/- mouse, we investigated the consequences of GAA deficiency on AT1 and AT2 cells using histology, pulmonary function and mechanics, and transcriptional analysis. Histological analysis revealed increased accumulation of lysosomal-associated membrane protein 1 (LAMP1) in the Gaa-/- mice lungs. Furthermore, ultrastructural examination showed extensive intracytoplasmic vacuoles enlargement and lamellar body engorgement. Respiratory dysfunction was confirmed using whole body plethysmography and forced oscillometry. Finally, transcriptomic analysis demonstrated dysregulation of surfactant proteins in AT2 cells, specifically reduced levels of surfactant protein D in the Gaa-/- mice. We conclude that GAA enzyme deficiency leads to glycogen accumulation in the distal airway cells that disrupts surfactant homeostasis and contributes to respiratory impairments in Pompe disease.NEW & NOTEWORTHY This research highlights the impact of Pompe disease on distal airway cells. Prior to this work, respiratory insufficiency in Pompe disease was classically attributed to pathology in respiratory muscles and motor neurons. Using the Pompe mouse model, we note significant pathology in alveolar type 1 and 2 cells with reductions in surfactant protein D and disrupted surfactant homeostasis. These novel findings highlight the potential contributions of alveolar pathology to respiratory insufficiency in Pompe disease.

Home-based enzyme replacement therapy in children and adults with Pompe disease; a prospective study

BACKGROUND

Pompe disease is a lysosomal storage disease treated with life-long enzyme replacement therapy (ERT). Home-based ERT has been provided in the Netherlands since 2008 because it diminishes the burden of treatment, increases patient flexibility and autonomy, and is thus a more patient-centred approach to ERT.

METHODS

All Dutch Pompe patients receiving alglucosidase alfa infusions at home were approached to participate in a questionnaire to validate the safety of home-based ERT. Prospective data on symptoms occurring during or within 48 h after infusion and retrospective data on infusion associated reactions (IARs) in the last three months were collected four times during one year.

RESULTS

In total, 116 out of 120 eligible patients (17 classic infantile, 2 atypical infantile, 15 childhood onset and 82 adult) filled out 423 questionnaires (response rate: 88.1%). Symptoms during or after infusion were reported 27 times in 17 patients. Fatigue was the most commonly reported health complaint (in 9.5% of patients). Four health complaints were judged to be IARs and reported to the Erasmus MC University Medical Center. None of the IARs reported in this study warranted emergency clinical care.

CONCLUSIONS

Our data demonstrate that home-based ERT in Pompe disease can be safely implemented as few, mostly mild, symptoms were reported during or after infusion. Insights from this study can be used as a base for implementing home-based ERT in other countries and to further optimize patient care, as unreported mild symptoms do not pose a health risk but may still be relevant to the patient.

Degeneration of muscle spindles in a murine model of Pompe disease

Pompe disease is a debilitating medical condition caused by a functional deficiency of lysosomal acid alpha-glucosidase (GAA). In addition to muscle weakness, people living with Pompe disease experience motor coordination deficits including an instable gait and posture. We reasoned that an impaired muscle spindle function might contribute to these deficiencies and therefore analyzed proprioception as well as muscle spindle structure and function in 4- and 8-month-old Gaa^-/- mice. Gait analyses showed a reduced inter-limb and inter-paw coordination in Gaa^-/- mice. Electrophysiological analyses of single-unit muscle spindle proprioceptive afferents revealed an impaired sensitivity of the dynamic and static component of the stretch response. Finally, a progressive degeneration of the sensory neuron and of the intrafusal fibers was detectable in Gaa^-/- mice. We observed an increased abundance and size of lysosomes, a fragmentation of the inner and outer connective tissue capsule and a buildup of autophagic vacuoles in muscle spindles from 8-month-old Gaa^-/- mice, indicating lysosomal defects and an impaired autophagocytosis. These results demonstrate a structural and functional degeneration of muscle spindles and an altered motor coordination in Gaa^-/- mice. Similar changes could contribute to the impaired motor coordination in patients living with Pompe disease.

Diagnostic Yield of Chilaiditi's Sign in Advanced-Phase Late-Onset Pompe Disease

PURPOSE

Chilaiditi's sign (CS), hepatodiaphragmatic interposition of the intestine, was caused by morphological abnormalities such as diaphragmatic atrophy, intestinal dilation, and liver atrophy. The sign is potentially important due to associations with clinically recurrent abdominal pain or even colonic volvulus. Late-onset Pompe disease (LOPD) could have the high prevalence of CS because of widened hepatodiaphragmatic space, following diaphragmatic atrophy, and the abnormal dilation of intestine caused by glycogen accumulation in smooth muscle of intestine. Our aim was to investigate the prevalence of CS in LOPD, and to identify the risk factors of CS in LOPD patients.

METHODS

Medical records of genetically confirmed patients of Pompe disease at the National Center Hospital, National Center of Neurology and Psychiatry were retrospectively reviewed. We evaluated CS using chest X-ray (CXR) and abdominal CT and assessed the prevalence of CS in LOPD patients. We also divided the patients into two groups, CS and non-CS group, and evaluated the factor associated with CS compared to clinical variables between groups.

RESULTS

Three of seven (43%) were detected in CS. CS group (P5-7) and non-CS group (P1-4) were obtained. In comparison of clinical variables, the severity of atrophy in right diaphragms was significantly higher in CS than non-CS groups (p = 0.029). Also, the frequency of abnormal position of right diaphragm and liver, and abnormally dilated bowel was seen in all of CS patients, but none of non-CS patient (p = 0.029, each).

CONCLUSION

In LOPD patients, the prevalence of CS was much higher of 43%, compared to healthy groups, or even in similarly respiratory muscle impaired neuromuscular diseases. The anatomically abnormal position of diaphragm and liver, atrophy and fat infiltration of diaphragms, and abnormally dilated bowel were significantly associated with CS in LOPD. We should pay more attention to CXR or abdominal CT as follow up in LOPD patients.

Macroglossia: A potentially severe complication of late-onset POMPE disease

BACKGROUND

Pompe disease is a rare neuromuscular disorder caused by a deficiency of a lysosomal enzyme, acid α-glucosidase. Macroglossia is a classic clinical sign of several inherited myopathies and has also been reported to occur progressively in late-onset Pompe disease (LOPD).

METHODS

We describe patients with LOPD and macroglossia included in the French national Pompe disease registry. Clinical, functional, and radiological data have been collected during periodic follow-up and analyzed retrospectively. These cases have been compared with 15 previously reported cases.

RESULTS

5 patients, 3 female and 2 males, from 71 to 88 years old, have been included in this study. All but one of the patients suffered from symptoms related to macroglossia before the diagnosis of Pompe disease. Three had localized tongue atrophy and one had significant localized tongue hypertrophy which led to glossectomy 10 years before diagnosis. Two patients had severe dysphagia, one of whom underwent gastrostomised for enteral nutritional support. One patient experienced the persistence of numerous sleep apneas despite nocturnal BiPAP ventilation. All our patients had dysarthria, and two required speech therapy. Four patients had a tongue hypersignal on MRI T1 sequences.

CONCLUSIONS

Detection of macroglossia should be part of the clinical diagnosis and follow-up of patients with LOPD, with a careful evaluation of its main consequences. Macroglossia can have severe functional impacts on speech, swallowing and sleep. Whole-body MRI with facial sections may facilitate the early diagnosis of Pompe disease with the "bright tongue sign".

New Insights into Gastrointestinal Involvement in Late-Onset Pompe Disease: Lessons Learned from Bench and Bedside

BACKGROUND

There are new emerging phenotypes in Pompe disease, and studies on smooth muscle pathology are limited. Gastrointestinal (GI) manifestations are poorly understood and underreported in Pompe disease.

METHODS

To understand the extent and the effects of enzyme replacement therapy (ERT; alglucosidase alfa) in Pompe disease, we studied the histopathology (entire GI tract) in Pompe mice (GAAKO 6^neo/6^neo). To determine the disease burden in patients with late-onset Pompe disease (LOPD), we used Patient-Reported Outcomes Measurements Information System (PROMIS)-GI symptom scales and a GI-focused medical history.

RESULTS

Pompe mice showed early, extensive, and progressive glycogen accumulation throughout the GI tract. Long-term ERT (6 months) was more effective to clear the glycogen accumulation than short-term ERT (5 weeks). GI manifestations were highly prevalent and severe, presented early in life, and were not fully amenable to ERT in patients with LOPD (n = 58; age range: 18-79 years, median age: 51.55 years; 35 females; 53 on ERT).

CONCLUSION

GI manifestations cause a significant disease burden on adults with LOPD, and should be evaluated during routine clinical visits, using quantitative tools (PROMIS-GI measures). The study also highlights the need for next generation therapies for Pompe disease that target the smooth muscles.

Cardiovascular disease in non-classic Pompe disease: A systematic review

Pompe disease is a rare inherited metabolic and neuromuscular disorder, presenting as a spectrum, with the classic infantile form on one end and the more slowly progressive non-classic form on the other end. While being a hallmark in classic infantile Pompe disease, cardiac involvement in non-classic Pompe disease seems rare. Vascular abnormalities, such as aneurysms and arterial dolichoectasia, likely caused by glycogen accumulation in arterial walls, have been reported in non-classic Pompe patients. With this first systematic review on cardiovascular disease in non-classic Pompe disease, we aim to gain insight in the prevalence and etiology of cardiovascular disease in these patients. Forty-eight studies (eight case-control studies, 15 cohort studies and 25 case reports/series) were included. Fourteen studies reported cardiac findings, 25 studies described vascular findings, and nine studies reported both cardiac and vascular findings. Severe cardiac involvement in non-classic Pompe disease patients has rarely been reported, particularly in adult-onset patients carrying the common IVS1 mutation. There are indications that intracranial dolichoectasia and aneurysms are more prevalent in non-classic Pompe patients compared to the general population. To further investigate the prevalence of cardiovascular disease in non-classic Pompe patients, larger case-control studies that also study established cardiovascular risk factors should be conducted.

Characterization of Gait and Postural Regulation in Late-Onset Pompe Disease

Pompe disease is a multisystemic disorder with the hallmark of progressive skeletal muscle weakness that often results in difficulties in walking and balance. However, detailed characterization of gait and postural regulation with this disease is lacking. The objective of this investigation was to determine if differences exist between the gait and postural regulation of LOPD patients and a matched control group. The gaits of 16 patients with LOPD were assessed using a gait analysis mobile system (RehaGait) and a dynamometric treadmill (FDM-T 1.8). The Interactive Balance System (IBS) was used to evaluate postural regulation and stability. All measures were compared to individual reference data. Demographic (age, gender), morphological (body height, body mass) and clinical data (muscle strength according to the Medical Research Council Scale (MRC Scale), as well as the 6-min walking test and a 10-m fast walk) were also recorded. Compared to individual reference data, LOPD patients presented with reduced gait velocity, cadence and time in single stand. A total of 87% of LOPD patients had abnormalities during posturographic analysis presenting with differences in postural subsystems. This study provides objective data demonstrating impaired gait and posture in LOPD patients. For follow-up analysis and as outcome measurements during medical or physiotherapeutic interventions, the findings of this investigation may be useful.

The Respiratory Phenotype of Pompe Disease Mouse Models

Pompe disease is a glycogen storage disease caused by a deficiency in acid α-glucosidase (GAA), a hydrolase necessary for the degradation of lysosomal glycogen. This deficiency in GAA results in muscle and neuronal glycogen accumulation, which causes respiratory insufficiency. Pompe disease mouse models provide a means of assessing respiratory pathology and are important for pre-clinical studies of novel therapies that aim to treat respiratory dysfunction and improve quality of life. This review aims to compile and summarize existing manuscripts that characterize the respiratory phenotype of Pompe mouse models. Manuscripts included in this review were selected utilizing specific search terms and exclusion criteria. Analysis of these findings demonstrate that Pompe disease mouse models have respiratory physiological defects as well as pathologies in the diaphragm, tongue, higher-order respiratory control centers, phrenic and hypoglossal motor nuclei, phrenic and hypoglossal nerves, neuromuscular junctions, and airway smooth muscle. Overall, the culmination of these pathologies contributes to severe respiratory dysfunction, underscoring the importance of characterizing the respiratory phenotype while developing effective therapies for patients.

Advances in imaging of brain abnormalities in neuromuscular disease

Brain atrophy, white matter abnormalities, and ventricular enlargement have been described in different neuromuscular diseases (NMDs). We aimed to provide a comprehensive overview of the substantial advancement of brain imaging in neuromuscular diseases by consulting the main libraries (Pubmed, Scopus and Google Scholar) including the more common forms of muscular dystrophies such as dystrophinopathies, dystroglycanopathies, myotonic dystrophies, facioscapulohumeral dystrophy, limb-girdle muscular dystrophy, congenital myotonia, and congenital myopathies. A consistent, widespread cortical and subcortical involvement of grey and white matter was found. Abnormalities in the functional connectivity in brain networks and metabolic alterations were observed with positron emission tomography (PET) and single photon emission computed tomography (SPECT). Pathological brain changes with cognitive dysfunction seemed to be frequently associated in NMDs. In particular, in congenital muscular dystrophies (CMDs), skeletal muscular weakness, severe hypotonia, WM abnormalities, ventricular dilatation and abnormalities in cerebral gyration were observed.

In dystroglycanopathy 2I subtype (LGMD2I), adult patients showed subcortical atrophy and a WM periventricular involvement, moderate ventriculomegaly, and enlargement of subarachnoid spaces. Correlations with clinical features have been observed with brain imaging characteristics and alterations were prominent in congenital or childhood onset cases. In myotonic dystrophy type 2 (DM2) symptoms seem to be less severe than in type 1 (DM1).

In Duchenne and Becker muscular dystrophies (DMD, BMD) cortical atrophy is associated with minimal ventricular dilatation and WM abnormalities.

Late-onset glycogenosis type II (GSD II) or Pompe infantile forms are characterized by delayed myelination. Only in a few cases of oculopharyngeal muscular dystrophy (OPMD) central nervous system involvement has been described and associated with executive functions impairment.

The impact of Pompe disease on smooth muscle: a review

Pompe disease (OMIM 232300) is an autosomal recessive disorder caused by mutations in the gene encoding acid α-glucosidase (GAA) (EC 3.2.1.20), the enzyme responsible for hydrolyzing lysosomal glycogen. The primary cellular pathology is lysosomal glycogen accumulation in cardiac muscle, skeletal muscle, and motor neurons, which ultimately results in cardiorespiratory failure. However, the severity of pathology and its impact on clinical outcomes are poorly described in smooth muscle. The advent of enzyme replacement therapy (ERT) in 2006 has improved clinical outcomes in infantile-onset Pompe disease patients. Although ERT increases patient life expectancy and ventilator free survival, it is not entirely curative. Persistent motor neuron pathology and weakness of respiratory muscles, including airway smooth muscles, contribute to the need for mechanical ventilation by some patients on ERT. Some patients on ERT continue to experience life-threatening pathology to vascular smooth muscle, such as aneurysms or dissections within the aorta and cerebral arteries. Better characterization of the disease impact on smooth muscle will inform treatment development and help anticipate later complications. This review summarizes the published knowledge of smooth muscle pathology associated with Pompe disease in animal models and in patients.

Late-onset Pompe disease: a genetic-radiological correlation on cerebral vascular anomalies

Pompe disease is an autosomal recessive disorder in which deficiency of the lysosomal enzyme acid alpha-glucosidase results in the accumulation of glycogen mostly in muscle tissues. Several reports suggest a higher incidence of intracranial vascular abnormalities (IVAs) in this condition, as well as brain microbleeds and cerebral vasculopathy. The aim of our study was to evaluate through neuroimaging studies the incidence of these anomalies in our cohort of late-onset Pompe disease (LOPD) patients asymptomatic for cerebrovascular disease, looking for correlations with clinical and genetic data. We studied 18 LOPD patients with brain magnetic resonance angiography (MRA), or contrast-enhanced computed tomography (CECT). Diameters of individual arteries were measured and compared with average values as proposed in the literature. We found IVAs in 13 of the 18 patients, mostly dilatative arteriopathy affecting the vertebrobasilar system. The anterior circle was involved in seven of the 18 patients. The diameter of the basilar artery at 1 cm was found to correlate both with age (spearman rho, p = 0.037) and disease duration (p = 0.004), but no other statistically significant correlation was documented. The incidence of intracranial dilatative arteriopathy in LOPD was higher than in the general population, confirming the literature data. However, we did not find intracranial aneurysms microbleeds or significant cerebrovascular disease. Abnormalities in the anterior and the posterior circle of Willis correlated with age and disease duration, but not with the severity of muscle/respiratory involvement or with genetic data. Further studies in larger cohorts of patients are needed to confirm these findings.

Airway smooth muscle dysfunction in Pompe (Gaa-/- ) mice

Pompe disease is an autosomal recessive disorder caused by a deficiency of acid α-glucosidase (GAA), an enzyme responsible for hydrolyzing lysosomal glycogen. Deficiency of GAA leads to systemic glycogen accumulation in the lysosomes of skeletal muscle, motor neurons, and smooth muscle. Skeletal muscle and motor neuron pathology are known to contribute to respiratory insufficiency in Pompe disease, but the role of airway pathology has not been evaluated. Here we propose that GAA enzyme deficiency disrupts the function of the trachea and bronchi and this lower airway pathology contributes to respiratory insufficiency in Pompe disease. Using an established mouse model of Pompe disease, the Gaa^-/- mouse, we compared histology, pulmonary mechanics, airway smooth muscle (ASM) function, and calcium signaling between Gaa^-/- and age-matched wild-type (WT) mice. Lysosomal glycogen accumulation was observed in the smooth muscle of both the bronchi and the trachea in Gaa^-/- but not WT mice. Furthermore, Gaa^-/- mice had hyporesponsive airway resistance and bronchial ring contraction to the bronchoconstrictive agents methacholine (MCh) and potassium chloride (KCl) and to a bronchodilator (albuterol). Finally, calcium signaling during bronchiolar smooth muscle contraction was impaired in Gaa^-/- mice indicating impaired extracellular calcium influx. We conclude that GAA enzyme deficiency leads to glycogen accumulation in the trachea and bronchi and impairs the ability of lower ASM to regulate calcium and respond appropriately to bronchodilator or constrictors. Accordingly, ASM dysfunction may contribute to respiratory impairments in Pompe disease.

The emerging phenotype of late-onset Pompe disease: A systematic literature review

BACKGROUND

Pompe disease is an autosomal recessive disorder caused by deficiency of the lysosomal glycogen-hydrolyzing enzyme acid α-glucosidase (GAA). The adult-onset form, late-onset Pompe disease (LOPD), has been characterized by glycogen accumulation primarily in skeletal, cardiac, and smooth muscles, causing weakness of the proximal limb girdle and respiratory muscles. However, increased scientific study of LOPD continues to enhance understanding of an evolving phenotype.

PURPOSE

To expand our understanding of the evolving phenotype of LOPD since the approval of enzyme replacement therapy (ERT) with alglucosidase alfa (Myozyme™/Lumizyme™) in 2006.

METHODS

All articles were included in the review that provided data on the charactertistics of LOPD identified via the PubMed database published since the approval of ERT in 2006. All signs and symptoms of the disease that were reported in the literature were identified and included in the review.

RESULTS

We provide a comprehensive review of the evolving phenotype of LOPD. Our findings support and extend the knowledge of the multisystemic nature of the disease.

CONCLUSIONS

With the advent of ERT and the concurrent increase in the scientific study of LOPD, the condition once primarily conceptualized as a limb-girdle muscle disease with prominent respiratory involvement is increasingly recognized to be a condition that results in signs and symptoms across body systems and structures.

Quantitative analysis of upright standing in adults with late-onset Pompe disease

Pompe disease is a rare disorder producing muscle weakness and progressive impairments in performing daily motor activities, such as walking and standing. Most studies have focused on dysfunctions at cellular level, restricting the examination of gross motor functions to qualitative or subjective rating scales evaluations. With the aim of providing an instrumented quantification of upright standing in Pompe disease, we used a force platform to measure the center of pressure over three foot positions and with eyes open and closed. Amplitude and variability of body sway were measured to determine the level of postural stability, while power spectrum analysis and nonlinear computations were performed to explore the structure of the postural control. In comparison with healthy participants, patients with Pompe disease showed a reduced level of postural stability, but irrelevant variations in frequency content and spatio-temporal structure of the sway motion were detected. Changes in foot position did not increase the postural instability associated with Pompe disease, but prominent worsening occurred in the patients when they stand with eyes closed, particularly along the anterior-posterior direction. These results provide objective elements to monitor deficiencies of upright standing in Pompe disease, emphasizing the specific contributions of sway direction and sensory deficits.

Neurologic Causes of Acute Respiratory Dysfunction

Many neurologic diseases can cause acute respiratory decompensation, therefore a familiarity with these diseases is critical for any clinician managing patients with respiratory dysfunction. In this article, we review the anatomy of the respiratory system, focusing on the neurologic control of respiration. We discuss general mechanisms by which diseases of the peripheral and central nervous systems can cause acute respiratory dysfunction, and review the neurologic diseases which can adversely affect respiration. Lastly, we discuss the diagnosis and general management of acute respiratory impairment due to neurologic disease.

Stroke in Young-Dilative Arteriopathy: A Clue to Late-Onset Pompe's Disease?

IMPORTANCE

In almost a third of stroke in young cases, etiology remains unclear. We report a radiological entity which might give a clue toward detection of late onset Pompe's disease in some cases.

OBSERVATION

Here we report two cases of stroke in young in which evaluation led to diagnosis of late onset Pompe's disease. Both patients presented with recurrent stroke. On evaluation, one of them was found to have slowly progressive predominantly proximal quadriparesis. His muscle biopsy showed Pompe's disease and had dolichoectasia of posterior circulation vessels. The other patient did not have any muscle weakness. Detailed workup for stroke in young was negative, but as angiogram showed intracranial vessel dolichoectasia, he was also investigated and found to have Pompe's disease.

CONCLUSIONS AND RELEVANCE

We conclude that dolichoectasia of intracranial vessels in cases with stroke in young, with or without muscle weakness, should raise a differential of late onset Pompe's disease. This being one of the few treatable disorders makes the diagnosis all the more important.

Successful combined liver/kidney transplantation from a donor with Pompe disease

Pompe disease results from inherited deficiency of the enzyme acid alpha-glucosidase resulting in lysosomal accumulation of glycogen primarily in skeletal muscle. Reported is the first case in which a donor with late onset Pompe disease (LOPD) was successfully used for deceased donor liver and kidney transplantation. This case demonstrates co-operative transplant surgery and genetic medicine evaluation and risk estimation for donors with inherited metabolic disorders some of which may be suitable for donation of selected organs for transplantation.

Are evoked potentials in patients with adult-onset pompe disease indicative of clinically relevant central nervous system involvement?

PURPOSE

Pompe disease is a multisystem autosomal recessive glycogen storage disease. Autoptic findings in patients with classic infantile and late-onset Pompe disease have proven that accumulation of glycogen can also be found in the peripheral and central nervous system. To assess the functional role of these pathologic findings, multimodal sensory evoked potentials were analyzed.

METHODS

Serial recordings for brainstem auditory, visual, and somatosensory evoked potentials of 11 late-onset Pompe patients were reviewed. Data at the onset of the enzyme replacement therapy with alglucosidase alfa were compared with follow-up recordings at 12 and 24 months.

RESULTS

Brainstem auditory evoked potentials showed a delayed peak I in 1/10 patients and an increased I-III and I-V interpeak latency in 1/10 patients, respectively. The III-V interpeak latencies were in the normal range. Visual evoked potentials were completely normal. Median somatosensory evoked potentials showed an extended interpeak latency in 3/9 patients. Wilcoxon tests comparing age-matched subgroups found significant differences in brainstem auditory evoked potentials and visual evoked potentials.

CONCLUSIONS

We found that the majority of recordings for evoked potentials were within the ranges for standard values, therefore reflecting the lack of clinically relevant central nervous system involvement. Regular surveillance by means of evoked potentials does not seem to be appropriate in late-onset Pompe patients.

Expanding our understanding of lower urinary tract symptoms and incontinence in adults with pompe disease

OBJECTIVE

To study the prevalence of lower urinary tract symptoms (LUTS) and incontinence in late-onset Pompe disease (LOPD) Methods: Adult LOPD patients seen at the Duke Pompe Clinic were prospectively recruited and asked to complete validated questionnaires on LUTS and incontinence as part of an IRB-approved study. Patient demographics as well as previous urologic history were reviewed.

RESULTS

35 patients with LOPD were included in the study (17 males and 18 females). The median age was 51.8 (range 18-72 years of age). Of these patients, 27/35 were receiving enzyme replacement therapy (ERT) with median duration of 54 months (range 5-88 months). In the male patients, 9/17 (53%) described their stream as dribbling, weak, or intermittent, and 9/17 (53%) complained of post-void dribbling. In addition 38% of the men were unable to stop their urination midstream. In the female patients, the most common complaint was urinary incontinence, reported in 14/18 (78%). In addition, 7/18 (39%) complained of post-void dribbling, and 47% were unable to stop their urination midstream. Bowel incontinence was reported in 45% of patients. There was a significant association between urinary symptoms and lower extremity function scores and duration of ERT (p = 0.005 and p = 0.04, respectively)

CONCLUSIONS

This is the first study in a large cohort of LOPD patients that demonstrates LUTS and incontinence occur at a high rate. This study emphasizes the spectrum of LOPD is beyond isolated gross motor and pulmonary involvement and has a significant effect on the lower urinary tract.

Quantitative assessment of lingual strength in late-onset Pompe disease

INTRODUCTION

Skeletal muscle is common in late-onset Pompe disease (LOPD). Recent data implicate common bulbar muscle involvement (i.e., the tongue).

METHODS

We used quantitative assessment of lingual strength to retrospectively determine the frequency and severity of lingual weakness in LOPD. We additionally examined associations between lingual strength and the presence or absence of dysarthria, and dysarthria severity.

RESULTS

Quantitative assessment revealed lingual weakness to be present in 80% of the sample. In the 24 affected patients, severity was mild in 29%, moderate in 29%, and severe in 42%. Patients with clinical dysarthria had greater lingual weakness than those without. As dysarthria severity increased, lingual strength decreased by an average of 6.82 kPa.

CONCLUSIONS

These quantitative data provide additional evidence for presence of bulbar muscle disease in patients with LOPD. Further study is necessary to determine functional effects, temporal progression, and effects of treatment.

Extraocular muscle function in adult-onset Pompe disease tested by saccadic eye movements

Glycogen storage disease type II (Pompe disease) affects mainly proximal skeletal muscles. Despite older histological evidence of extraocular muscle involvement, ocular motor palsies or other eye movement abnormalities are not considered part of the clinical picture. We investigated the dynamics of saccadic eye movements of five patients suffering from late-onset Pompe disease and compared their performance to that of age matched healthy controls. Horizontal rightward and leftward saccades were recorded binocularly, while subjects looked at LED targets placed at ±5°, 10° and 15° eccentricities. No differences in saccade amplitudes, peak velocities or durations were observed between controls and patients. More specifically, for 5° saccades, patients had a mean peak velocity of 146°/s with duration of 76ms. For 10° and 15° saccades these values were 258°/s, 86ms and 324°/s, 101ms respectively, thereby lying well within one standard deviation of the mean of normal data. Moreover, saccadic amplitude accuracy was also unimpaired. These results indicate that patients with late onset Pompe disease perform fast and accurate horizontal saccades without evidence of muscle paresis or other ocular motor abnormalities. Reported histological abnormalities of extraocular muscles do not appear to have a phenotypic impact.

Urge incontinence and gastrointestinal symptoms in adult patients with pompe disease: a cross-sectional survey

OBJECTIVE

To determine the frequency and impact of gastrointestinal symptoms, and bowel and urinary incontinence, as this is currently unknown in adults with Pompe disease.

METHODS

Adult German Pompe patients and age- and gender-matched controls were asked about symptoms in the upper and lower intestinal tract as well as urinary incontinence using the Gastrointestinal Symptoms Questionnaire and the International Consultation on Incontinence Questionnaires for Bowel Symptoms and Urinary Incontinence.

RESULTS

The overall response rate was 78%; 57 patients and 57 controls participated. The mean age of the patients was 48.3 years ±14.7 (28 female, 29 male). 84% of patients were receiving enzyme replacement therapy. Stool urgency, diarrhoea, and urinary urge incontinence were reported significantly more frequently in patients compared to the age- and gender-matched controls (55%, 56%, 33% vs. 20%, 18%, 7%). 20% of Pompe patients used loperamide daily against diarrhoea. No other gastrointestinal tract-related symptoms were reported to occur more frequently in Pompe patients than in controls.

CONCLUSIONS

Compared to age- and gender-matched controls, both urinary and bowel incontinence occur in a higher frequency in adults with Pompe disease and have a major impact on daily life.

Neuronopathic lysosomal storage diseases: clinical and pathologic findings

BACKGROUND

The lysosomal-autophagocytic system diseases (LASDs) affect multiple body systems including the central nervous system (CNS). The progressive CNS pathology has its onset at different ages, leading to neurodegeneration and early death.

METHODS

Literature review provided insight into the current clinical neurological findings, phenotypic spectrum, and pathogenic mechanisms of LASDs with primary neurological involvement.

CONCLUSIONS

CNS signs and symptoms are variable and related to the disease-specific underlying pathogenesis. LAS dysfunction leads to diverse global cellular consequences in the CNS ranging from specific axonal and dendritic abnormalities to neuronal death. Pathogenic mechanisms for disease progression vary from impaired autophagy, massive storage, regional involvement, to end-stage inflammation. Some of these features are also found in adult neurodegenerative disorders, for example, Parkinson's and Alzheimer's diseases. Lack of effective therapies is a significant unmet medical need.

Glycogenosome accumulation in the arrector pili muscle in Pompe disease

BACKGROUND

Glycogenosis type II or Pompe disease is an autosomal-recessive lysosomal storage disease due to mutations in the gene encoding acid alpha-glucosidase (GAA), an enzyme required for lysosomal glycogen degradation. The disease predominantly affects the skeletal and respiratory muscles but there is growing evidence of the involvement of smooth muscle cells in blood vessel walls, suggesting a multi-system disorder. Moreover, the failure of autophagy in Pompe disease could contribute to muscular atrophy and disease progression and is thought to compromise the efficacy of enzyme replacement therapy (ERT).

METHODS

We investigated the light microscopical and ultrastructural pathology of the arrector pili muscle from punch skin biopsies from the calf of 6 adult Pompe disease patients and 6 age and gender matched healthy controls. Two patients had a follow-up biopsy after 19 and 20 month of ERT.

RESULTS

The electron microscopic investigation of patient biopsies revealed the widespread occurrence of glycogenosomes, membrane bound accumulations of granular glycogen, associated with autophagic vacuoles. In the controls we detected only muscle cells with non-membrane bound forms of glycogen. These morphological changes in smooth muscle cells are similar to those seen in skeletal muscle and smooth muscle cells of arterioles of Pompe patients. Furthermore, two patients with pre- and post-ERT skin biopsies showed a decrease in the number of cells with extensive autophagy after treatment.

CONCLUSIONS

Electron microscopic examination of the arrector pili muscles appears to be a surrogate marker for the involvement of smooth muscles reflecting disease severity. These findings suggest that the standardized and widely used skin biopsy could offer a minimally invasive way to screen for smooth muscle involvement and warrant further studies in larger cohorts of patients.

The brain in late-onset glycogenosis II: a structural and functional MRI study

BACKGROUND

Late-onset glycogenosis type II (GSD II) is a rare, multisystem disorder mainly affecting limb and respiratory muscles due to acid alpha glucosidase deficiency. Despite evidence at autopsy of glycogen accumulation in the brain, no study exploring brain functions is yet available.

OBJECTIVE

Our objective in this study was to assess brain changes in late-onset GSD II.

METHODS

Each patient underwent a standardized neuropsychological assessment, regional grey-matter (GM) atrophy, and resting-state functional magnetic resonance imaging (RS-fMRI). Functional connectivity maps of the salience (SN) and default-mode (DMN) networks were considered. A group of age- and gender-matched healthy controls was enrolled for MRI comparisons. P values family-wise error (FWE) cluster level corrected inferior to 0.05 were considered.

RESULTS

Nine GSD II patients (age 46.6 ± 8.0; 55% male) were recruited. No significant GM atrophy was found in patients compared with controls (n = 18; age 48.0 ± 9.8,;40% male). Functional connectivity within the SN was selectively reduced in patients, and cingulate gyrus and medial frontal cortex were mainly involved. Accordingly, patients had significant impairment of executive functions (as measured by Wisconsin Card Sorting test), whereas other cognitive domains were within mean normal ranges.

CONCLUSIONS

Our findings extend the clinical spectrum of GSD II by indicating that brain changes occur in this muscular disorder. Above all, these results should lead to better examinations of therapeutic approaches and perspectives for the affected patients. Further studies evaluating in depth these issues are warranted.

Low anal sphincter tone in infantile-onset Pompe Disease: an emerging clinical issue in enzyme replacement therapy patients requiring special attention

Pompe Disease (PD) is a lysosomal storage disease caused by acid α-glucosidase deficiency. The infantile form typically results in death in the first year of life. Patient survival has improved with enzyme replacement therapy (ERT), but new complications are being recognized. We report three cases of infantile onset PD on ERT who present with a new finding of poor anal tone, a finding that requires special attention for further complications such as rectal prolapse.

Oropharyngeal dysphagia may occur in late-onset Pompe disease, implicating bulbar muscle involvement

Late-onset Pompe disease (presenting after 12 months of age) often presents with limb-girdle and respiratory weakness, but oropharyngeal dysphagia has not been reported previously. A retrospective review of all late-onset Pompe disease patients evaluated in the neuromuscular clinic at Duke University Medical Center from 1999-2010 was performed. Twelve patients were identified and 3 had symptoms of oropharyngeal dysphagia. The medical record was reviewed, including the results of electromyography, videofluroscopic swallow examinations, and motor speech examination including instrumental assessment of lingual force with the Iowa Oral Performance Instrument. Oropharyngeal dysphagia was mild in two cases and severe in one. One of the two patients with mild severity demonstrated oral stage swallow signs; in the other, residual material was observed in the area of the cervical esophagus. In the patient with severe oropharyngeal dysphagia, both the oral and pharyngeal stages of swallowing were affected with penetration and aspiration documented. The degree of swallowing impairment appeared to correlate with overall physical strength and function. Oropharyngeal dysphagia may occur in patients with late-onset Pompe disease, implicating bulbar muscle involvement. Screening for symptoms of dysphagia may help reduce morbidity and mortality, while improving understanding of the late-onset Pompe disease phenotype. Further studies, including examination of the relationship between lingual weakness and oropharyngeal dysphagia, are warranted.

Pregnancy during enzyme replacement therapy for late-onset acid maltase deficiency

We report the case of a female patient who developed Pompe's disease when she was 19. She received enzyme replacement therapy from the age of 35, and after three years of treatment the improvement in her clinical condition was such that she was able to consider having a baby. It was the patient's wishes to continue with her treatment throughout the entirety of her pregnancy. There were no complications, but there was a clear deterioration in motor and respiratory functions. She delivered at term by Caesarean section, and the child was healthy. Six months later, we noted an improvement of her motor and respiratory functions. The child was developing normally.

Autopsy findings in late-onset Pompe disease: a case report and systematic review of the literature

BACKGROUND

Late-onset Pompe disease (LOPD) is a rare cause of declining proximal muscle strength and respiratory function that can also affect other organ systems. The development of enzyme replacement therapy has made it one of the few inherited muscle disorders with treatment, but clinical response is difficult to assess due to the variable and often slow progression of illness. A better understanding of the disease's systemic effects can be gleaned through autopsy findings.

PURPOSE

The purpose of this study was to: (1) describe the histological findings observed in LOPD, (2) provide correlations between reported histological and clinical findings, and (3) review the literature on autopsy findings in LOPD.

METHODS

Histological evaluation of autopsy tissues from a 62-year-old woman with LOPD was conducted. A clinical history was obtained by review of the medical records. The literature was reviewed for previously reported histological and clinical findings in LOPD. Based on this case report and information from prior publications, histological and clinical findings for the disease were correlated.

RESULTS

Histologic examination revealed mostly mild vacuolar myopathy typical of glycogen accumulation within skeletal and smooth muscle cells. The most prominent vacuolar myopathy was in quadriceps muscle, which also exhibited chronic myositis with degenerating and regenerating muscle fibers. Transmission electron microscopy disclosed lysosomal glycogen accumulation within skeletal, cardiac, and vascular smooth muscle cells, correlating with published case reports of basilar artery and ascending aortic aneurysms and carotid artery dissection. Organs containing smooth muscle cells (the bladder, intestine, and esophagus) were also affected, explaining reports of symptoms such as urinary incontinence and dysphagia. In addition to glycogen accumulation, there was obvious damage to the contraction apparatus of myofibrils within cardiac and skeletal muscle cells. These histological and ultrastructural findings correlate with the clinical manifestations of LOPD.

CONCLUSIONS

This study is the first to describe histological findings of LOPD utilizing both traditional paraffin-processed tissues and epoxy resin embedded tissues for high-resolution light microscopy. The findings are similar to those seen in previous studies, but with improved morphological detail and glycogen preservation. This patient exhibited histological involvement of multiple organs, correlating with the clinical features of LOPD. With the advent of definitive therapy for Pompe disease, it is important to be aware of these findings and use them to develop methods for tracking therapeutic response.

Cardiovascular abnormalities in late-onset Pompe disease and response to enzyme replacement therapy

PURPOSE

We evaluated the prevalence of cardiovascular abnormalities and the efficacy and safety of enzyme replacement therapy in patients with late-onset Pompe disease.

METHODS

Ninety patients were randomized 2:1 to enzyme replacement therapy or placebo in a double-blinded protocol. Electrocardiograms and echocardiograms were obtained at baseline and scheduled intervals during the 78-week study period. Baseline cardiovascular abnormalities, and efficacy and safety of enzyme replacement therapy were described. Three pediatric patients were excluded.

RESULTS

Eighty-seven patients were included. Median age was 44 years; 51% were men. At baseline, a short PR interval was present in 10%, 7% had decreased left ventricular systolic function, and 5% had elevated left ventricular mass on echocardiogram (all in mild range). There was no change in cardiovascular status associated with enzyme replacement therapy. No significant safety concerns related to enzyme replacement therapy were identified.

CONCLUSIONS

Although some patients with late-onset Pompe disease had abnormalities on baseline electrocardiogram or echocardiogram, those classically seen in infantile Pompe disease, such as significant ventricular hypertrophy, were not noted. Cardiovascular parameters were not impacted by enzyme replacement therapy, and there were no cardiovascular safety concerns. The cardiovascular abnormalities identified may be related to Pompe disease or other comorbid conditions.

High-density areas on muscle CT in childhood-onset Pompe disease are caused by excess calcium accumulation

We report two patients with childhood-onset Pompe disease showing striking changes with high-density areas on skeletal muscle CT, not seen in adult- or infantile-onset forms of this disease. While the anterior compartment of the thigh muscles was less affected in the adult-onset form, the rectus femoris and tibial muscles were preferentially involved from the early stage in the childhood-onset form of Pompe disease. The high-density areas became increasingly diffuse with disease progression, producing a marbled pattern and ultimately resulting in homogeneous high density and muscle atrophy. Muscle biopsy specimens from the high-density areas showed striking vacuolar changes with many dense globular bodies in lysosomes. High calcium signals were identified by X-ray microanalysis using energy-dispersive X-ray spectroscopy in these areas. Excess calcium accumulation in the vacuoles was also confirmed with the glyoxal-bis(2-hydroxyanil) (GBHA) staining. The high density on CT was slightly reduced together with clinical improvement after enzyme replacement therapy in patient 2. Our data demonstrate that in childhood-onset Pompe disease, high-density areas on skeletal muscle CT images are due to the accumulation of calcium in dense globular bodies formed by a chronic degenerative process affecting autophagic vacuoles.

Abnormalities of cerebral arteries are frequent in patients with late-onset Pompe disease

Cerebral aneurysms and arteropathies causing severe cerebrovascular events have been reported as rare complications in patients with late-onset Pompe disease. We investigated the frequency of cerebrovascular anomalies in six patients with late-onset Pompe disease followed at our institution. Clinical data collection and magnetic resonance angiography were performed as part of routine annual examinations. Four out of six patients had brain vascular anomalies including dolichoectasia of the basilar artery and ectasia of internal carotids. These patients also complained of gastrointestinal symptoms (chronic constipation and gastrointestinal reflux). Two patients had clinical signs related to the arteriopathy, including partial paralysis of the third cranial nerve and transient ischemic attacks. At 1 year follow-up, enzyme replacement therapy did not modify the size of cerebral vessels, but patients reported a marked improvement of intestinal symptoms. In conclusion, neurologists should be aware that intracranial artery abnormalities are not infrequent in patients with late-onset Pompe disease, and they should be specifically investigated in the presence of unexplained CNS symptoms.

Clinical and histologic ocular findings in pompe disease

PURPOSE

Limited information is available on the ocular findings in patients with Pompe disease.

METHOD

This study summarizes this information with a systematic literature review; reports the ocular histologic findings seen in a deceased infant with Pompe disease who was receiving enzyme replacement therapy and in a deceased adult with late-onset Pompe disease; and notes the new observation of ptosis in children with infantile-onset Pompe disease who are receiving enzyme replacement therapy.

RESULTS

Six articles were found on the ultrastructural-histopathologic eye findings in Pompe disease. Previously reported clinical ocular findings included strabismus and ptosis. Glycogen accumulation and vacuolar myopathy have been seen histologically.

CONCLUSION

Based on these clinical and histologic reports, patients with Pompe disease may have an increased incidence of ocular abnormalities, such as ptosis and strabismus, and therefore should undergo ophthalmologic examination.

Late onset Pompe disease: Clinical and neurophysiological spectrum of 38 patients including long-term follow-up in 18 patients

To describe the clinical and neurophysiological spectrum and prognosis in a large cohort of biochemically and genetically proven late onset Pompe patients. Thirty-eight diagnosed with late onset Pompe disease at our neuromuscular department during 1985 and 2006 are described in detail. The mean delay from onset of symptoms or first medical consultation until diagnosis was 10.4 and 7.1 years, respectively. A different diagnosis was suggested in 11 of 38 patients. Ten patients underwent repeated muscle biopsies before diagnosis of Pompe disease was established. Limb girdle weakness was the most frequent presenting sign. Six patients complained of myalgia. Wolf-Parkinson-White syndrome was found in 3 of 38 patients. Respiratory failure preceded the onset of overt limb muscle weakness in three patients. The course of the patients was progressive in all, but there was a wide variety of progression, which did not correlate with the age of disease onset. In 71% of the patients, neurophysiological investigations revealed a myopathic EMG pattern, half of the patients had spontaneous activity including complex repetitive discharges. A normal EMG was found in 9% of the patients. Nerve conduction studies were normal in all. Pompe disease should be taken into consideration in patients with unexplained limb girdle muscular weakness with respiratory failure. Cardiac manifestations may not be restricted to infantile Pompe disease.

Adult-onset glycogen storage disease type 2: clinico-pathological phenotype revisited

The need for clinical awareness and diagnostic precision of glycogen storage disease type 2 (GSD2) has increased, as enzyme replacement therapy has become available. So far, only small series have reported the muscle pathology of late-onset GSD2. We reassessed 43 muscle biopsies of 38 GSD2 patients. In all patients the diagnosis of GSD2 has been established by biochemistry and/or mutational analysis of the GAA gene. Additionally to the expected morphological features, ultrastructural analysis revealed a high incidence of autophagic vacuoles, lipofuscin debris, structural Z-line disorganization and histological neurogenic-like pattern that were not thoroughly appreciated, previously. Comparing age at onset and morphology, excessive vacuolar and autophagic myopathy and mitochondrial disorganization of virtually all fibres is common in infants. At juvenile onset, a more moderate vacuolization without significant differences in overall morphology is notable. At late-onset, the spectrum of vacuolar myopathy is more divergent, ranging from almost normal to severe. Here pronounced secondary alterations are observed that include lipofuscin debris, autophagic vacuoles with residual lysosomal bodies and granular inclusions, structural mitochondrial and Z-line texture alterations. Moreover, there is a high incidence of subtle neurogenic-like alteration in all subtypes. Nineteen patients were genetically tested; in 15 patients the common leaky splicing mutation c.-45T>G (or IVS1-13T>G) in intron1 of the GAA gene was found on at least one allele, facilitating genetic screening. In our patients, GAA genotype appears not to be associated with secondary alterations such as autophagic vacuoles, structural alterations or neurogenic-like changes. These findings may have implications for our understanding of the pathogenesis of GSD2 and for assessing therapeutic success of enzyme replacement therapy.

Anaplerotic diet therapy in inherited metabolic disease: therapeutic potential

Beginning with phenylketonuria, dietary therapy for inborn errors has focused primarily on the restriction of the precursor to an affected catabolic pathway in an attempt to limit the production of potential toxins. Anaplerotic therapy is based on the concept that there may exist an energy deficit in these diseases that might be improved by providing alternative substrate for both the citric acid cycle (CAC) and the electron transport chain for enhanced ATP production. This article focuses on this basic problem, as it may relate to most catabolic disorders, and provides our current experience involving inherited diseases of mitochondrial fat oxidation, glycogen storage, and pyruvate metabolism using the anaplerotic compound triheptanoin. The observations have led to a realization that 'inter-organ' signalling and 'nutrient sensors' such as adenylate monophosphate mediated-protein kinase (AMPK) and mTOR (mammalian target of rapamycin) appear to play a significant role in the intermediary metabolism of these diseases. Activated AMPK turns on catabolic pathways to augment ATP production while turning off synthetic pathways that consume ATP. Information is provided regarding the inter-organ requirements for more normal metabolic function during crisis and how anaplerotic therapy using triheptanoin, as a direct source of substrate to the CAC for energy production, appears to be a more successful approach to an improved quality of life for these patients.

The natural course of non–classic Pompe’s disease; a review of 225 published cases

Pompe's disease is a neuromuscular disorder caused by deficiency of lysosomal acid alpha-glucosidase. Recombinant human alpha- glucosidase is under evaluation as therapeutic drug. In light of this development we studied the natural course of cases not fitting the definition of classic infantile Pompe's disease. Our review of 109 reports including 225 cases shows a continuous spectrum of phenotypes. The onset of symptoms ranged from 0 to 71 years. Based on the available literature, no criteria to delineate clinical sub-types could be established.A common denominator of these cases is that first symptoms were related to or caused by muscle weakness. In general, patients with a later onset of symptoms seemed to have a better prognosis. Respiratory failure was the most frequent cause of death. CK, LDH, ASAT, ALAT and muscle glycogen levels were frequently but not always elevated. In most cases a muscle biopsy revealed lysosomal pathology, but normal muscle morphology does not exclude Pompe's disease. In 10% of the cases in which the enzyme assay on leukocytes was used, a normal alpha-glucosidase activity was reported. Data on skeletal muscle strength and function, pulmonary function, disability, handicap and quality of life were insufficiently reported in the literature. Studies of non-classic Pompe's disease should focus on these aspects, before enzyme replacement therapy becomes generally available.

Constitutively active AMP kinase mutations cause glycogen storage disease mimicking hypertrophic cardiomyopathy

Mutations in PRKAG2, the gene for the gamma 2 regulatory subunit of AMP-activated protein kinase, cause cardiac hypertrophy and electrophysiologic abnormalities, particularly preexcitation (Wolff-Parkinson-White syndrome) and atrioventricular conduction block. To understand the mechanisms by which PRKAG2 defects cause disease, we defined novel mutations, characterized the associated cardiac histopathology, and studied the consequences of introducing these mutations into the yeast homologue of PRKAG2, Snf4. Although the cardiac pathology caused by PRKAG2 mutations Arg302Gln, Thr400Asn, and Asn488Ile include myocyte enlargement and minimal interstitial fibrosis, these mutations were not associated with myocyte and myofibrillar disarray, the pathognomonic features of hypertrophic cardiomyopathy caused by sarcomere protein mutations. Instead PRKAG2 mutations caused pronounced vacuole formation within myocytes. Several lines of evidence indicated these vacuoles were filled with glycogen-associated granules. Analyses of the effects of human PRKAG2 mutations on Snf1/Snf4 kinase function demonstrated constitutive activity, which could foster glycogen accumulation. Taken together, our data indicate that PRKAG2 mutations do not cause hypertrophic cardiomyopathy but rather lead to a novel myocardial metabolic storage disease, in which hypertrophy, ventricular pre-excitation and conduction system defects coexist.

Pathological features of glycogen storage disease type II highlighted in the knockout mouse model

Glycogen storage disease type II (GSDII; Pompe's disease) is an autosomal recessive disease caused by lysosomal alpha-glucosidase deficiency. Skeletal muscle weakness is the most conspicuous clinical symptom of patients suffering from GSDII and skeletal muscle also is prominently involved in the knockout mouse model of this disease. Thus far, however, little detailed information has been published on the pathological changes in other mouse tissues. This paper aims to provide these data and gives a record of the clinical course of the mouse model over a 2-year period. Four-month-old affected mice perform worse in a running wheel than their unaffected littermates, but do not yet display other clear signs of disease. The lysosomal glycogen storage, already evident at birth, becomes more severe in time, leading to muscle wasting by 9-10 months of age and then limb girdle weakness and kyphosis. The disease does not markedly shorten the animal's life span despite the serious tissue pathology, which is not limited to heart and skeletal muscle, but is also seen in the smooth muscle of blood vessels and of the respiratory, digestive, and urogenital tracts. In addition, the mice have lysosomal glycogen storage in the liver, kidney, spleen, and salivary gland; in Schwann cells of the peripheral nerves, and in a subset of neurons in the central nervous system. By pathological criteria, the knockout mouse model parallels the human infantile form of GSDII and is attractive for studying the possible reversal of tissue pathology and symptomatology under different therapeutic regimes.

Muscle computed tomography in adult-onset acid maltase deficiency

Nine patients with adult-onset acid maltase deficiency (Pompe's disease) were examined clinically and with computed tomography (CT). The CT scan showed early and severe involvement of the muscles of trunk and thighs, with selective sparing of the tensor fasciae latae, short head of biceps femoris, gracilis, and sartorius muscles. Shoulder and leg muscles were less affected. The disease spread over the years from trunk to extremities. Muscle strength and CT findings were positively correlated.

Skeletal muscle weakness and dysphagia caused by acid maltase deficiency: nutritional consequences of coincident celiac sprue

BACKGROUND

A 30-year-old woman with celiac sprue had progressive weight loss, myalgia, limb-girdle weakness, and dysphagia.

METHODS AND RESULTS

Barium swallow showed an atonic esophagus, and scintigraphic study confirmed esophageal dysmotility. Skeletal muscle biopsy showed characteristic appearances of acid maltase deficiency, which was confirmed by a reduction of leukocyte acid alpha-glucosidase activity.

CONCLUSIONS

Nutritional factors may have accelerated the presentation of the lysosomal storage disorder. This is the first reported case of dysphagia caused by esophageal motor weakness in acid maltase deficiency.

Clinical variability in adult-onset acid maltase deficiency: report of affected sibs and review of the literature

Acid maltase deficiency (AMD) is a rare cause of muscle disease in adult patients. The present report of 2 sibs and review of 36 previously reported cases illustrates the vast clinical variability in adult-onset AMD. This is 1 of only 3 reports to document tongue weakness and enlargement in an adult with AMD. The presenting signs and symptoms usually include progressive limb weakness, restrictive lung disease, or both. Consistent supportive abnormalities include a modest elevation in serum CK, a reduction in the forced vital capacity, and abnormal spontaneous activity (that is, myotonic discharges or fibrillations) in resting muscles during needle electromyography. The clinical spectrum is also extended to include distal limb weakness, scapular winging, asymmetric muscle weakness, and tongue involvement.