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Mutations in the acid alpha-glucosidase gene (M. Pompe) in a patient with an unusual phenotype.

Glycogenosis type II (Pompe disease) is a lysosomal storage disease caused by deficiency of acid alpha-glucosidase (acid maltase). The disease is autosomal recessive inherited and is clinically and genetically heterogenous. The authors describe a 30-year-old woman affected by late-onset Pompe disease with vascular affection resembling atherosclerotic angiopathy of the elderly. Genetic analysis revealed two novel mutations (Ala237Val and Gly293Arg) in the acid alpha-glucosidase gene in this patient.

Adult↗

Alloxan diabetic neuropathy: electron microscopic studies.

Peripheral nerves of diabetic rats were studied 2 years after alloxan injection. We observed demyelination and remyelination, axonal degeneration and regeneration, reduplication of basal laminae around vessels and Schwann's cells, as well as onion bulb formation by proliferated Schwann's cells. Crystalline deposits composed of aggregates of fibrillary electron dense material often occurred in vessel walls and endoneurium of diabetic animals but rarely were seen in nerves from age-matched control animals. Glycogen accumulated in myelinated and unmyelinated axons within mitochondria. Axoplasmic inclusions resembling Lafora's bodies and the inclusions of glycogenosis type IV were frequent and often were accompanied by deposits of particulate glycogen. The findings suggest that the neuropathy in alloxan diabetes is caused by metabolic impairment of anxons, Schwann's cells, and vessels, leading to segmental demyelination and axonal degeneration.

Animals↗

Lysosomal glycogen storage disease with normal acid maltase.

Two unrelated 16-year-old boys had mental retardation, cardiomegaly, and proximal myopathy. One also had hepatomegaly. Histochemistry and electronmicroscopy of muscle biopsies showed lysosomal glycogen storage resembling acid maltase deficiency. Biochemical studies of skeletal muscle showed increased content of glycogen of normal structure; acid alpha-glucosidase activity in both urine and muscle was normal. Other enzymes of glycogen metabolism were also normal. The cause of this apparently generalized glycogenosis with no demonstrable enzyme defect is unknown.

Acid Phosphatase↗

Increased plasma uric acid after exercise in muscle phosphofructokinase deficiency.

Type VII glycogenosis (muscle phosphofructokinase deficiency) is attended by hyperuricemia and hyperuricosuria. In one patient, we found that exercise on a bicycle ergometer increased plasma uric acid, inosine, and hypoxanthine levels. Forearm exercise also markedly increased venous inosine, hypoxanthine, and ammonia in the exercising arm of two patients. Exaggerated release of precursors for uric acid synthesis from exercising muscle may be related to the hyperuricemia.

Adult↗

A non-ischemic forearm exercise test for the screening of patients with exercise intolerance.

BACKGROUND: The forearm exercise test is a common investigation that allows detection of some metabolic myopathies. It is not completely standardized and, when performed in ischemic conditions, may induce rhabdomyolysis in patients with glycogenosis. OBJECTIVE: To develop a standardized non-ischemic exercise test for a safe screening of patients with exercise intolerance. METHODS: Twenty-six healthy subjects and 32 patients with exercise intolerance performed an isometric exercise at 70% of the maximal voluntary contraction during 30 seconds in non-ischemic conditions. Blood concentrations of creatine kinase, lactate, and ammonia were analyzed. RESULTS: A nearly fourfold lactate rise was induced by exercise in healthy subjects. All patients with normal muscle biopsy showed values similar to those of healthy subjects. No significant lactate increase was observed in six patients with a myophosphorylase defect and one with a debrancher defect. Disparate lactate responses were observed in 14 patients with a mitochondrial myopathy. The blood lactate level at rest was abnormally high in four of these patients. The lactate surface normalized by the mechanical energy production was above the normal range in eight patients. CONCLUSIONS: The authors propose a standardized non-ischemic grip test that overcomes the main drawbacks of the classic ischemic forearm exercise test. It provides a specific, efficient, and safe screening test for patients with exercise intolerance. Its sensitivity was very good for patients with a glycogenolysis defect but remains partial in patients with a mitochondrial disorder.

Adult↗

[Pseudohypertrophic myopathy caused by cysticercosis. Report of a case].

A 25 years old woman was admitted with a history of apparent hypertrophy of the calves, specially on the left, slight pain in the legs and difficulty in walking. Electromyography showed giant motor unit potentials with complete interference pattern. Biopsy of both gastrocnemii was performed revealing a cysticercus among inflammatory infiltrate and changes of the muscle fibers. Review of the literature disclosed 12 other reported cases. The age ranged from 10 to 35 years with a median of 25 years. Pseudohypertrophic myopathy due to cysticercosis has been found twice more common in males than in females. History of epilepsy and muscle pain occurs in about one half of the cases and muscle weakness in about one third of them. Usually there is simultaneous involvement of the upper and lower limb girdles. Myotonia is rare but subcutaneous nodules are frequently found. Our case is unique in the literature in which the pseudohypertrophy was confined to the legs and electromyography showed giant motor unit potentials. The pathogenesis of this condition is discussed and attention is called to the differential diagnosis with other pseudohypertrophic muscular conditions such as pseudohypertrophic muscular dystrophy, myotonia congenita, trichinosis, hypothyroidism, amyloidosis and glycogenosis of type I (Pompe's disease) in its juvenile form.

Adult↗

[Motor nerve conduction study in McArdle disease: case report].

McArdle disease (glycogenosis type V) is a metabolic myopathy with symptoms of exercise intolerance caused by deficiency of the enzyme myophosphorylase. In these patients, the motor nerve conduction studies after a short period of maximal voluntary muscle contraction or repetitive stimulation reveals characteristic findings of the disease. A 37-year-old man presented symptoms of exercise intolerance, muscular fatigue and cramps in the beginning of the physical activity with "second wind" phenomenon. The motor nerve conduction studies after a voluntary contraction of 30 and 90 seconds presented decrease in the amplitude of the compound muscle action potential in median, ulnar and deep peroneal nerves; and decrement after 200 stimulation at the 40 Hz in deep peroneal nerve. The electromyography presented myopathic pattern and during the ischemic exercise electric silence was not proven. The characteristic of electrophysiological studies are discussed with emphasis at the importance of the motor nerve conduction studies in the patients with suspicion of metabolic myopathy.

Action Potentials↗

[Hepatic viscerotomy (its contribution to the study of regional nosology)].

As a part of a routine yellow fever surveillance program going on in the south of Bahia State, Brazil, liver fragments were obtained through postmortem viscerotomy from 702 individuals who died after presenting acute febrile illness from 1981 up till 1991. Instead of being only screened for the presence of yellow fever, the liver tissue was thoroughly evaluated by histopathology. More than a third of the cases exhibited marked and diffuse steatosis occurring in malnourished infants and young children. Hepatic fibrosis, granulomatous disease compatible with disseminated tuberculosis, advanced schistosomiasis, chronic alcoholic injury, chronic hepatitis and cirrhosis were also frequently observed. A miscellaneous group of hepatic pathological processes were also recognized, which included such diverse entities as Hodgkin's disease, glycogenosis, sickle-cell disease, hepatocarcinoma, etc. Only 124 (17.7%) cases showed normal hepatic histology. The wide possibility of histological diagnoses strongly indicates that the material obtained by viscerotomy can be further explored by an interested pathologist, to help in the understanding of nosology and epidemiology, concerning remote geographic areas where viscerotomy is being routinely performed.

Adolescent↗

Detection of PHKA2 gene mutation in four Japanese patients with hepatic phosphorylase kinase deficiency.

We analyzed the PHKA2 gene in four Japanese families with hepatic phosphorylase kinase (PhK) deficiency. Mutational analysis of PHKA2 cDNA was performed by reverse-transcribed polymerase chain reaction (RT-PCR) and direct sequencing, and each mutation was confirmed on the genomic DNA. In boys with low erythrocyte PhK activity (i.e., x-linked liver glycogenosis [XLG] type I), deletion of exon 2 (splice site mutation of 79-1 G > T) or nonsense mutation of Q1169X or R497X was identified. However, missense mutation of R295C was identified in one boy with normal erythrocyte PhK activity (i.e., XLG type II). This mutation was not found in 100 control alleles, and was considered responsible for presentation of the XLG type II phenotype. Excluding Q1169X, all mutations detected in this study represented novel mutations. All mothers were found to be heterozygous carriers of the mutations. Gene analysis was confirmed to represent a useful procedure for diagnosing XLG type II, for which liver biopsy had previously been required to detect hepatic PhK deficiency.

Child, Preschool↗

RNA sequencing resolves a novel noncanonical splice-region variant in PHKA2 causing glycogen storage disease type IX α2: a case report.

BACKGROUND: Glycogen storage disease type IX α2 (GSD IX α2) is an X-linked hepatic glycogenosis caused by pathogenic variants in PHKA2. Noncanonical splice-region variants located outside the invariant GT/AG dinucleotides pose significant interpretive challenges, as in silico predictions alone are often insufficient for definitive classification. CASE DESCRIPTION: We report a 2.9-year-old boy presenting with short stature, hepatomegaly, markedly elevated aminotransferases, fasting hypoglycemia with ketonuria, hypercholesterolemia, coagulation parameter abnormalities (decreased fibrinogen and prolonged thrombin time), and histological evidence of early hepatic fibrosis as demonstrated by Masson's trichrome staining (portal fibrosis and perisinusoidal fibrosis). Whole-exome sequencing (WES) identified a hemizygous, previously unreported PHKA2 variant [NM_000292.3:c.2517+5G>T, genomic location (GRCh38): NC_000023.11: g.18907895G>T], initially classified as a variant of uncertain significance (VUS) under American College of Medical Genetics and Genomics (ACMG) criteria. RNA sequencing of peripheral blood leukocytes demonstrated predominant exon 22 skipping in 94.2% of informative junction reads, predicting a frameshift and premature termination codon [p.(Gly788Profs*74)] with predicted loss of the C-terminal CBL 2 subdomain. Incorporating this transcript-level evidence, the variant was reclassified as pathogenic (PVS1 + PM2_Supporting + PP4). Following dietary management with uncooked cornstarch supplementation, the patient showed progressive biochemical improvement over a 2.2-year follow-up. CONCLUSIONS: This case expands the mutational spectrum of PHKA2 and demonstrates that RNA sequencing of accessible tissues is a practical and diagnostically informative strategy for resolving noncanonical splice-region variants in pediatric hepatic GSD. Early hepatic fibrosis detected by histological examination before age 3 years underscores the importance of longitudinal hepatic surveillance in GSD IX α2.

Glycogen storage disease type IX α2 (GSD IX ↗

Muscle fatigue during high-intensity exercise in children.

Children are able to resist fatigue better than adults during one or several repeated high-intensity exercise bouts. This finding has been reported by measuring mechanical force or power output profiles during sustained isometric maximal contractions or repeated bouts of high-intensity dynamic exercises. The ability of children to better maintain performance during repeated high-intensity exercise bouts could be related to their lower level of fatigue during exercise and/or faster recovery following exercise. This may be explained by muscle characteristics of children, which are quantitatively and qualitatively different to those of adults. Children have less muscle mass than adults and hence, generate lower absolute power during high-intensity exercise. Some researchers also showed that children were equipped better for oxidative than glycolytic pathways during exercise, which would lead to a lower accumulation of muscle by-products. Furthermore, some reports indicated that the lower ability of children to activate their type II muscle fibres would also explain their greater resistance to fatigue during sustained maximal contractions. The lower accumulation of muscle by-products observed in children may be suggestive of a reduced metabolic signal, which induces lower ratings of perceived exertion. Factors such as faster phosphocreatine resynthesis, greater oxidative capacity, better acid-base regulation, faster readjustment of initial cardiorespiratory parameters and higher removal of metabolic by-products in children could also explain their faster recovery following high-intensity exercise.From a clinical point of view, muscle fatigue profiles are different between healthy children and children with muscle and metabolic diseases. Studies of dystrophic muscles in children indicated contradictory findings of changes in contractile properties and the muscle fatigability. Some have found that the muscle of boys with Duchenne muscular dystrophy (DMD) fatigued less than that of healthy boys, but others have reported that the fatigue in DMD and in normal muscle was the same. Children with glycogenosis type V and VII and dermatomyositis, and obese children tolerate exercise weakly and show an early fatigue. Studies that have investigated the fatigability in children with cerebral palsy have indicated that the femoris quadriceps was less fatigable than that of a control group but the fatigability of the triceps surae was the same between the two groups. Further studies are required to elucidate the mechanisms explaining the origins of muscle fatigue in healthy and diseased children. The use of non-invasive measurement tools such as magnetic resonance imaging and magnetic resonance spectroscopy in paediatric exercise science will give researchers more insight in the future.

Age Factors↗

Deficiency of phosphofructo-1-kinase/muscle subtype in humans is associated with impairment of insulin secretory oscillations.

In healthy humans, insulin is secreted in an oscillatory manner. While the underlying mechanisms generating these oscillations are not fully established, increasing evidence suggests a central role for phosphofructo-1-kinase/muscle subtype (PFK1-M), which also serves as the predominantly active PFK1 subtype in the pancreatic beta-cell. The fact that normal oscillatory secretion is impaired in subjects with impaired glucose tolerance and healthy relatives of patients with type 2 diabetes suggests that this defect may be involved in the secretory dysfunction. To evaluate a possible link between inherited PFK1-M deficiency in humans (Tarui's disease or glycogenosis type VII) and altered insulin oscillations, in vivo studies were performed. We determined basal insulin oscillations during 2 h of frequent plasma sampling in two related teen-aged individuals with homozygous and heterozygous PFK1-M deficiency compared with nondeficient, unrelated control subjects. As predicted by the underlying hypothesis, normal oscillations in insulin secretion were completely abolished in the individual with homozygous deficiency of PFK1-M and significantly impaired in the heterozygous individual, as shown by spectral density and autocorrelation analyses. Thus, deficiency of PFK1-M subtype in humans appears to be associated with an impaired oscillatory insulin secretion pattern and may contribute to the commonly observed secretion defects occurring in type 2 diabetes.

Adult↗

Testing for undesirable traits in cattle: an Australian perspective.

A variety of autosomal recessive defects, many lethal to the newborn calf, have been recognized in Australia. Definition of a defect at the biochemical or molecular level facilitates development of heterozygote detection tests essential for efficient disease control programs. The prevalence of alpha-mannosidosis in Angus and Murray Greys, generalized glycogenosis in Brahmans and Shorthorns, and citrullinemia in Holstein/Friesians has been reduced as a result of industry-sponsored disease-control programs. These defects were disseminated as a consequence of selection focused on desirable traits carried by individuals. In the long term, an increase in crossbreeding in commercial beef production will reduce the significance of recessive defects. Caution will be required to reduce the risk of dissemination of recessive defects resulting from increased selection pressure within the dairy industry presently dominated by Holstein/Friesians.

Animal Welfare↗

A case of flutamide-induced acute cholestatic hepatitis--a case report.

Flutamide, an oral nonsteroidal, antiandrogenic, anilid compound which inhibits the uptake and binding of androgens to nuclear receptors in the prostate, is used with or without LH-RH analogues for treatment of patients with metastatic carcinoma of the prostate. Clinically significant hepatotoxicities such as toxic hepatitis, cholestatic hepatitis, hepatic failure, and even death have rarely been reported in the English literature, but no case has been reported in Korea. A 75-year-old man with metastatic carcinoma of the prostate had taken flutamide (750 mg/day) for 7 months and suddenly developed jaundice and general weakness. The findings of blood chemistries were compatible with cholestatic hepatitis, but ultrasonography, viral marker and auto-antibody studies did not reveal any attributable causes. Histologic examination of a sono-guided liver biopsy only disclosed centrilobular cholestasis, nuclear glycogenosis and mild sinusoidal lymphocytic infiltration. Discontinuation of flutamide resulted in an almost full recovery of the patient's liver function in 2 months. We, herein, report a case of flutamide-induced acute choestatic hepatitis with a brief review of the literature.

Acute Disease↗

[McArdle's disease. Apropos of a case].

McArdle's disease (glycogenosis type V) is a metabolic disorder of hydrocarbons, inherited with autosomic recessive pattern. Biochemically is defined by a myophosphorylase deficiency; clinically it is characterized by exercise intolerance, due to the impossibility of providing energetic substrate to the muscle, myalgias and stiffness. We present a case report of a patient with McArdle's disease and we comment the diagnostic procedures and current therapeutic options.

Adult↗

[McArdle's disease (a familial case)].

The author describes a family (48 year old mother and 15 year old son) with the muscular variant of glycogenosis-McArde's metabolic myopathy. The mother has been ill since 22 years old, the son--since 7. The disease had a slowly progressive development. The clinical picture was characterized by convulsions of the type of cramps following physical loadings on muscles of the body and extremities. Convulsions were accompanied by pain, an induration and enlargment of the muscles, muscle fatigue and increased significantly in an artifical ischemia of the extremities. A histochemical study of the muscle revealed a pathological accumulation of glycogen. The content of lactic and pyruvic acid in the blood after work in ischemic conditions did not change significantly. A study of the sugar curve in the blood with a loading with glucose and a parallel determination of insulin by a radioimmune method found hyperinsulinemia and a dysfunction of the pancreas.

Adolescent↗

[Phospho-hexo-isomerase deficiency].

Hematologic, genetic and biochemical data of two patients suffering from glucosephosphate isomerase deficiency are described. In one of them a generalized deficiency could be demonstrated. The molecular instability of the deficient enzyme results in early inactivation. Its consequences for carbohydrate metabolism are exposed. Besides a non-spherocytic hemolytic anemia, a hepatic glycogenosis could be observed. Our patients are compared to litterature.

Anemia, Hemolytic, Congenital Nonspherocytic↗

[Mechanical ventilation in neuromuscular diseases: do not start too early, but certainly not too late].

Three patients had chronic respiratory disorders: a 42-year-old man with glycogenosis type II was tired, had headaches, poor pulmonary function values and, according to the arterial blood gas values, hypercapnia; a man aged 24 with Duchenne's muscular dystrophy had variable moderate dyspnoea with hypoxia and hypercapnia, and a man aged 64 years with an mitochondrial myopathy complained of dyspnoea and headache but had good blood gas values. The symptoms and abnormalities of the first patient were suppressed by nocturnal ventilatory support through a nasal mask system, the second preferred to refrain from ventilatory support and died a few weeks later and the symptoms of the third patient decreased without ventilatory support. Assessing a ventilatory disorder in patients with a neuromuscular disease is not always simple. Symptoms suggestive of nocturnal hypoventilation may occur in patients without respiratory insufficiency. It is also possible for patients with chronic respiratory insufficiency to be free of symptoms. Determinations of the arterial blood gas values are the most reliable method. Since normal daytime values do not exclude a nocturnal respiratory insufficiency, it is advisable in case of suspicion of nocturnal hypoventilation to measure the arterial blood gas values at night, as well. Nocturnal pulse oximetry does not always adequately reflect the degree of hypoventilation. In view of the positive effects of assisted respiration, adequate diagnostic examinations and early referral to a centre for home mechanical ventilation are advisable.

Adult↗