[Multicenter retrospective study of 38 cases with fumarate hydratase deficiency uterine leiomyoma]

Objective: To investigate the clinicopathological features of fumarate hydratase (FH) deficiency uterine leiomyoma. Methods: The data of 38 patients with FH deficiency uterine leiomyoma were screened and analyzed. The expressions of FH, S-(2-succino)-cysteine (2SC), desmin, p16, p53, CD₁₀ and cell proliferation associated nuclear antigen (Ki-67) proteins were detected by immunohistochemistry, and their clinicopathological features were analyzed retrospectively. Results: (1) Clinical features: the median age of the patients was (42.5±7.4) years old. Twenty-one cases (55%) of them were myomas found in physical examination, and the median maximum diameter of the tumor was 6.0 cm (range: 5.0-7.5 cm); myomectomy was performed in 23 cases (61%), total hysterectomy with or without bilateral appendages in 15 cases (39%); laparoscopic surgery in 27 cases (71%), open surgery in 11 cases (29%); none of the patients had renal cell carcinoma. (2) Histological features: atypical nuclear cells were distributed locally or diffusely, eosinophilic nucleoli and intranuclear inclusion bodies could be seen, glass like globules could be seen in the cytoplasm, nuclear division was 0-4/10 high power field (HPF), and antler like blood vessels and pulmonary edema-like changes could be seen in the stroma. Among 38 patients with FH deficiency uterine leiomyoma, FH was negative in 37 cases (97%), and positive in 1 case (3%); 2SC, desmin, p16, p53, CD₁₀ and Ki-67 showed focal positive expression in 38 cases (100%), including 35 cases (92%) with Ki-67 index<10% and 3 cases (8%) with Ki-67 index ≥10%. (3) Follow-up: 4 cases (11%) recurred, and there was no death. There were significant differences in age, family history, distribution of atypical nuclei and mitosis number between recurrent group and non-recurrent group (all P<0.05). Conclusions: FH deficiency uterine leiomyoma is a rare tumor, which needs pathological examination,immunohistochemical examination and clinical history. Patients younger than 43 years old, with family history, histologically atypical diffuse nuclear distribution and mitotic number ≥3/10 HPF should be alert to the risk of recurrence.

De Novo Heterozygous POLR2A Variants Cause a Neurodevelopmental Syndrome with Profound Infantile-Onset Hypotonia

The RNA polymerase II complex (pol II) is responsible for transcription of all ∼21,000 human protein-encoding genes. Here, we describe sixteen individuals harboring de novo heterozygous variants in POLR2A, encoding RPB1, the largest subunit of pol II. An iterative approach combining structural evaluation and mass spectrometry analyses, the use of S. cerevisiae as a model system, and the assessment of cell viability in HeLa cells allowed us to classify eleven variants as probably disease-causing and four variants as possibly disease-causing. The significance of one variant remains unresolved. By quantification of phenotypic severity, we could distinguish mild and severe phenotypic consequences of the disease-causing variants. Missense variants expected to exert only mild structural effects led to a malfunctioning pol II enzyme, thereby inducing a dominant-negative effect on gene transcription. Intriguingly, individuals carrying these variants presented with a severe phenotype dominated by profound infantile-onset hypotonia and developmental delay. Conversely, individuals carrying variants expected to result in complete loss of function, thus reduced levels of functional pol II from the normal allele, exhibited the mildest phenotypes. We conclude that subtle variants that are central in functionally important domains of POLR2A cause a neurodevelopmental syndrome characterized by profound infantile-onset hypotonia and developmental delay through a dominant-negative effect on pol-II-mediated transcription of DNA.

Branching enzyme deficiency/glycogenosis storage disease type IV presenting as a severe congenital hypotonia: muscle biopsy and autopsy findings, biochemical and molecular genetic studies

The fatal infantile neuromuscular presentation of branching enzyme deficiency (glycogen storage disease type IV) due to mutations in the gene encoding the glycogen branching enzyme, is a rare but probably underdiagnosed cause of congenital hypotonia. We report an infant girl with severe generalized hypotonia, born at 33 weeks gestation who required ventilatory assistance since birth. She had bilateral ptosis, mild knee and foot contractures and echocardiographic evidence of cardiomyopathy. A muscle biopsy at 1 month of age showed typical polyglucosan storage. The autopsy at 3.5 months of age showed frontal cortex polymicrogyria and polyglucosan bodies in neurons of basal ganglia, thalamus, substantia innominata, brain stem, and myenteric plexus, as well as liver involvement. Glycogen branching enzyme activity in muscle was virtually undetectable. Sequencing of the GBE1 gene revealed a homozygous 28 base pair deletion and a single base insertion at the same site in exon 5. This case confirms previous observations that GBE deficiency ought to be included in the differential diagnosis of congenital hypotonia and that the phenotype correlates with the 'molecular severity' of the mutation.

[Pompe's disease. Part I: pathogenesis and clinical features]

Pompe's disease is an ultra-orphan disease caused by the deficiency of lysosomal alpha-glucosidase. At present, it is the only inherited muscle disorder, which can be treated by replacement of the enzyme. According to the natural course, early infantile and late childhood-juvenile-adult cases are known. Respiratory insufficiency, cardiomyopathy, and muscle hypotonia are cardinal symptoms/signs in infantile Pompe's disease, while cardiomyopathy is absent in adult-onset cases. CK levels are always elevated in the sera of infantile patients. Hip-girdle dystrophy and orthopnoe should alert suspicion in adult patients. Diagnosis is established by decreased activity of the enzyme or mutational analysis. Muscle biopsy can be misleading in adult cases due to absence of glycogen in the examined specimen. In this review, we also discuss our experiences obtained by the treatment of three patients.

Mevalonic aciduria: report of two cases

Mevalonic aciduria is a rare disease that is a consequence of a deficiency of mevalonate kinase, an inborn error in the biosynthesis of cholesterol. Approximately 30 cases have been reported. We present our data on two siblings with mevalonic aciduria as a contribution to the recognition of this subject. Both were born after uneventful pregnancies. Their parents were healthy and not consanguineous. They had normal somatic and psychomotor development until they were around 2 years old. After the second year of life they developed mental retardation, ataxia and hypotonia. MRI showed cerebellar atrophy of both hemispheres and vermis. One sibling, from the age of 10 years onwards, suffered from complex partial seizures that were controlled with levetiracetam and lamotrigine. At 11 and 12 years of age, respectively, they were able to walk without help, but their gait was broad and ataxic. Their speech was dysarthric, fine motor skills were impaired as result of cerebellar ataxia, and they had moderate mental retardation. Diagnosis of mevalonic aciduria was made at this age through urinary organic acid analysis by gas chromatography-mass spectroscopy, which revealed high urinary excretion of mevalonic acid. They are currently 18 and 17 years old, respectively, show mental retardation and are able to walk but with difficulty. In our patients, ataxia due to cerebellar atrophy and mental retardation have been the predominant clinical manifestations. In mildly affected patients who survive infancy, these seem to be the predominant findings.

Glycine decarboxylase mutations: a distinctive phenotype of nonketotic hyperglycinemia in adults

Three unrelated adult patients with mild hyperglycinemia, infantile hypotonia, mental retardation, behavioral hyperirritability, and aggressive outbursts were screened for glycine decarboxylase (GLDC) mutations; two novel missense mutations (A389V and R739H) were found. Both mutations had a 6 to 8% of normal GLDC activities when expressed in COS7 cells.

Long-term follow-up and adult outcome of 6-pyruvoyl-tetrahydropterin synthase deficiency

Little information is available on the long-term course and adult outcome of patients with 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency. We describe the course of a 32-year-old woman with hypotonia, dystonia, choreoathetosis, mental retardation, behavioral disturbances, and incomplete puberty due to PTPS deficiency. From the age of 6 months she developed progressive hypotonia and choreoathtetoid movements despite good control of hyperphenylalaninemia. Tetrahydrobiopterin deficiency was diagnosed at age 3 years. She had a dramatic response to L-dopa, which persisted at a stable dose for 29 years. Reducing the L-dopa dose led to severe axial hypotonia and limb dystonia, and increasing it led to florid abnormal movements and behavioral disorders. This report illustrates the role of dopamine modulation in motor, psychiatric, and endocrine functions.

Reinvestigation of trihydroxycholestanoic acidemia reveals a peroxisome biogenesis disorder

OBJECTIVE

To determine the enzymatic defect in a patient with ataxia, dysarthric speech, dry skin, hypotonia, and absent reflexes. The patient was previously diagnosed with a presumed deficiency of trihydroxycholestanoyl-CoA oxidase.

BACKGROUND

Peroxisomes harbor a variety of metabolic functions, including fatty acid beta-oxidation, etherphospholipid biosynthesis, phytanic acid alpha-oxidation, and L-pipecolic acid oxidation. This patient was previously described with an isolated peroxisomal beta-oxidation defect caused by a deficiency of the enzyme trihydroxycholestanoyl-CoA oxidase. This was based on the pattern of accumulating metabolites.

METHODS

Measurement of beta-oxidation enzymes, peroxisomal biochemical analysis in body fluids and cultured skin fibroblasts, and DNA analysis of the PEX12 gene were performed.

RESULTS

An isolated beta-oxidation defect in this patient was excluded by measurement of the various beta-oxidation enzymes. The authors found that the patient had a peroxisome biogenesis disorder caused by mutations in the PEX12 gene, although all peroxisomal functions in cultured skin fibroblasts were normal.

CONCLUSIONS

The absence of clear peroxisomal abnormalities in the patient's fibroblasts, including a normal peroxisomal localization of catalase, implies that even when all peroxisomal functions in fibroblasts are normal, a peroxisome biogenesis disorder cannot be fully excluded, and further studies may be needed. In addition, the authors' findings imply that there is no longer evidence for the existence of trihydroxycholestanoyl-CoA oxidase deficiency as a distinct disease entity.

Mental retardation and hypotonia seen in the knock out mouse for Canavan disease is not due to succinate semialdehyde dehydrogenase deficiency

Canavan disease (CD) is an autosomal recessive disorder caused by aspartoacylase deficiency leading to accumulation of N-acetylaspartic acid and spongy degeneration of the brain. The mouse model for CD showed low levels of glutamate and gamma-aminobutyric acid (GABA) in the brain. Whether the low levels of glutamate and GABA observed in the CD mouse brain lead to abnormal production of glutamate-GABA associated enzymes and resulting succinate production is not obvious. While glutamate dehydrogenase and alpha-ketoglutarate dehydrogenase complex activities are lower in the cerebellum and brain stem of the CD mouse, alanine aminotransferase and succinate semialdehyde dehydrogenase (SSADH) activities and succinate level are similar to the levels observed in the wild type. Deficiency of SSADH has been suggested to be associated with mental retardation and hypotonia, similar to the clinical features of CD. The normal SSADH activity in the CD mouse brain suggests that mental retardation and hypotonia seen in the CD mouse is not due to SSADH activity and if documented also in patients with CD.

The hypotonic infant: case study of central core disease

Causes of hypotonia in the newborn can be broadly categorized into two classifications. Hypotonia with a supraspinal origin may be seen with systemic disease, hypoxic ischemic encephalopathy, cerebral malformations, syndromes (for example: Down, Prader-Willi, Lowe, Zellweger, Smith-Lemli-Opitz), and c-spine injury. Disorders of the motor unit that present with hypotonia in the newborn period include SMA, congenital myotonic dystrophy, congenital myasthenia gravis, and congenital myopathies. Central core disease is one of the classic congenital myopathies that can be differentiated based on characteristic histologic findings. Muscle fiber samples from patients with central core disease possess distinct morphology that can be diagnostic. Many infants may not exhibit muscle weakness in the newborn period, although there have been rare cases of profound hypotonia and respiratory failure. Clearly, muscle biopsy is the gold standard and is indicated for any infant with marked hypotonia that is not thought to be supraspinal in origin.

Mitochondrial dysfunction in patients with hypotonia, epilepsy, autism, and developmental delay: HEADD syndrome

A group of 12 children clinically presenting with hypotonia, intractable epilepsy, autism, and developmental delay, who did not fall into previously described categories of mitochondrial encephalomyopathy, were evaluated for mitochondrial respiratory enzyme activity levels, mitochondrial DNA, and mitochondrial structural abnormalities. Reduced levels in specific respiratory activities were found solely in enzymes with subunits encoded by mitochondrial DNA in seven of eight biopsied skeletal muscle specimens evaluated. Five cases exhibited increased levels of large-scale mitochondrial DNA deletions, whereas pathogenic point mutations previously described in association with mitochondrial encephalomyopathies were not found. Mitochondrial structural abnormalities were present in three of four patients examined. Our findings suggest that mitochondrial dysfunction, including extensive abnormalities in specific enzyme activities, mitochondrial structure, and mitochondrial DNA integrity, may be present in children with a clinical constellation including hypotonia, epileptic seizures, autism, and developmental delay. The acronym HEADD is presented here to facilitate pursuit of mitochondrial defects in patients with this clinical constellation after other causes have been excluded.

Tyrosine hydroxylase deficiency unresponsive to L-dopa treatment with unusual clinical and biochemical presentation

Tyrosine hydroxylase (TH) deficiency is generally considered as a cause of the autosomal recessive form of dopa-responsive dystonia, also known as Segawa disease. Clinical hallmarks comprise parkinsonian and other extrapyramidal symptoms. Biochemically the defect leads to the defective synthesis of catecholamines, in particular dopamine. The diagnosis relies on a characteristic pattern of biogenic amine metabolites exclusively in the CSF and can be confirmed by establishing a mutation in the TH gene. Here we present a patient meeting all diagnostic criteria, including a new homozygous mutation (926T > C) with confirmed parental heterozygosity, extrapyramidal symptoms, but atypical other symptoms with periodic neurological episodes observed every 4 days and unresponsive to dopa treatment. The CSF biochemical abnormalities were severe. Uncharacteristically, a strongly abnormal urinary catecholamine metabolite pattern was also consistently observed. The atypical presentation of this patient shows that the clinical and metabolic phenotype of TH deficiency is more variable than formerly thought, and that the condition should no longer be considered as a treatable disorder per se.

Confirmation of prenatal diagnosis results of X-linked recessive myotubular myopathy by mutational screening, and description of three new mutations in the MTM1 gene

X-linked recessive myotubular myopathy (XLMTM; MTM1) is a severe neonatal disorder often causing perinatal death of the affected males. The responsible gene, designated MTM1, was localized to proximal Xq28 and recently isolated. The characterization of MTM1 allowed us to screen for causing mutations in three families, previously investigated by linkage analysis. Using exon amplification, single strand conformation polymorphism, and subsequent sequencing analysis, three new mutations and their mutational origin were characterized by analyzing 10 exons. An acceptor splice site and a frameshift mutation were correlated with the concurrent appearance of XLMTM in two families. A third intronic mutation was also analyzed by reverse transcription PCR and revealed a cryptic splice site mutation cosegregating with the presumed XLMTM haplotype in the third family. These results further support the implication of the MTM1 gene in XLMTM and allow efficient and reliable carrier and prenatal diagnosis in these families. Direct mutational diagnosis of families at risk in combination with haplotype analysis avoid the drawbacks using only linkage analysis, make genetic counselling far more reliable, and early clinical management of this disease more appropriate. Moreover, pedigree analyses provide first information on de novo mutation frequency in this newly identified human disease gene.

Skeletal muscle mitochondrial defects in nonspecific neurologic disorders

A group of 25 children (5 months to 20 years of age) presenting with intractable seizures, developmental delay, and severe hypotonia, who did not fall into the known categories of mitochondrial encephalomyopathies, underwent muscle biopsy for evaluation of mitochondrial function and were compared with age-matched control subjects. Biopsied skeletal muscle was analyzed for six mitochondrial enzyme-specific activities, mitochondrial DNA point mutations and deletions, and mitochondrial DNA levels. The data reveal a high incidence of specific mitochondrial enzyme activity defects. Reduced activity levels were evident in complex I (11 patients), III (24 patients), IV (nine patients), and V (10 patients). Two patients also exhibited pronounced reduction in mitochondrial DNA levels (80% reduction compared with control subjects). Two patients manifested increased levels of 5-kb and 7.4-kb mitochondrial DNA deletions. Pathogenic mutations previously described in association with mitochondrial encephalomyopathies were not evident. The data suggest that mitochondrial dysfunction, including extensive defects in specific enzyme activities, may be frequently present in children with seizures, developmental delay, and hypotonia that do not fall within the known mitochondrial encephalomyopathies. These mitochondrial deficiencies can be primarily ascertained by biochemical analysis and are rarely accompanied by mitochondrial ultrastructural changes. The molecular basis of these defects, their role in these disorders, and potential treatment warrant further study.

Infantile muscle phosphorylase-b-kinase deficiency. A case report

A Turkish girl is described who showed a severe floppy infant syndrome and respiratory failure at birth. She suffered upper respiratory tract infections and pneumonia. She was ventilated and had hypercapnoea secondary to bradypnoea. Biochemical analysis of skeletal muscle revealed a slightly increased glycogen content, and enzymatic analysis revealed a muscle phosphorylase-b-kinase deficiency. The infant succumbed after 140 days due to persistent apnoea and asystole. Isolated muscle phosphorylase-b-kinase deficiency should be considered as a possible diagnosis in floppy infants.

Stridor as the major presenting symptom in riboflavin-responsive multiple acyl-CoA dehydrogenation deficiency

Inspiratory stridor of unknown origin was the leading clinical symptom in an 11-month-old boy. The stridor increased over a period of 4 weeks, and assisted ventilation became necessary. Selective urinary screening by gas chromatography/mass spectrometry analysis revealed excretion of ethylmalonic and 3-OH-isovaleric acid and of N-isobutyryl-, N-2-methylbutyryl-, N-isovaleryl-, N-hexanoyl- and N-suberylglycine. Neither hypoglycaemia nor metabolic acidosis were noticed. Treatment with 200 mg of riboflavin per day led to a dramatic clinical improvement with restoration of normal respiration and an increase in muscular tone within 2 months. During this period, metabolite excretion in urine completely normalized. Riboflavin-sensitive multiple acyl-CoA dehydrogenation deficiency was confirmed in cultured fibroblasts. With riboflavin supplementation, the development of the child has been favourable, with normal school attendance now at an age of 9 years.

CONCLUSION

As respiratory symptoms might precede other symptoms in disorders of mitochondrial oxidation, we propose determination of urinary organic acids in all cases of unexplained laryngeal stridor.

Aromatic L-amino acid decarboxylase deficiency: clinical features, diagnosis, and treatment of a second family

Aromatic L-amino acid decarboxylase deficiency is an inborn error of metabolism that leads to combined serotonin and catecholamine deficiency, first described by Hyland et al in 1990. The clinical features, biochemical findings, and treatment of the second family with this condition are reported. Our male patient presented with developmental delay, extreme hypotonia, oculogyric crises, and irritability. The diagnosis of this inborn error of biogenic amine metabolism was accomplished by determining low concentrations of homovanillic, 5-hydroxyindoleacetic acid, and 3-methoxy-4-hydroxyphenyl-ethyleneglycol in cerebrospinal fluid with normal biopterin metabolism and increased L-dopa, in plasma, cerebrospinal fluid, and urine. Greatly reduced activity of aromatic L-amino acid decarboxylase in plasma confirmed this diagnosis. Combined treatment with pyridoxine, tranylcypromine, and bromocriptine produced some clinical improvement.

A deletion in the long arm of chromosome 18 in a child with serum carnosinase deficiency

The dipeptides carnosine and anserine, found exclusively in meats, are hydrolyzed in serum by the enzyme carnosinase. Several reports of serum carnosinase deficiency describe a variable phenotype, which ranges from normal to severe psychomotor retardation, hypotonia, and myoclonic seizures in the first year of life. We report the case of a 30-mo-old girl with hypotonia, developmental delays, and tremor. Although consuming nominal quantities of meal, she excreted large amounts of carnosine and anserine. A strict meat-free diet ameliorated, but did not eliminate, these abnormalities. Serum carnosinase activity was found to be extremely low. Analysis of this child's chromosomes revealed a terminal deletion of chromosome 18 with breakpoint at q21.3. Neither parent exhibited this deletion, suggesting it was generated de novo in the patient or in a parental germ cell. Molecular studies showed that the patient's paternal chromosome 18 was deleted. Urinary carnosine excretion and serum carnosinase activity were normal in the patient's father. The mother had low carnosinase activity. The patient's brother exhibited moderate hypercarnosinuria and intermediate enzyme activity, consistent with the carrier state for carnosinase deficiency. Cumulatively, these findings suggest that the locus for this enzyme resides on the distal long arm of chromosome 18, and they are consistent with an unusual mechanism for the inheritance of this, typically autosomal recessive, condition. We conclude that this patient is likely hemizygous for the defect, having received the deficiency allele from her mother and, by virtue of the chromosomal deletion, no allele from her father. This represents the first report of a chromosomal abnormality in association with serum carnosinase deficiency and should aid in further localization of the gene encoding serum carnosinase.

Cerebellar hypoplasia in respiratory chain dysfunction

Disruption of early or late fetal brain development resulting in structural abnormalities may be associated with inborn errors of mitochondrial metabolism. It is common in patients with deficiency of pyruvate dehydrogenase activity and it has sporadically been described in patients with dysfunction of the tricarboxylic acid cycle. Mitochondrial respiratory chain disorders are not commonly known to interfere with early brain development. We describe here a girl with an encephalomyopathy likely to be due to a novel type of deficiency of cytochrome c oxidase (complex IV) activity that presented with severe hypotonia, myoclonic seizures, optic atrophy and elevated lactate concentration in cerebrospinal fluid shortly after birth. Cranial magnetic resonance imaging revealed hypoplasia of the cerebellum with rudimentary cerebellar hemispheres and relative sparing of the vermis. This case suggests that deficiency of cytochrome c oxidase and possibly respiratory chain disorders in general have to be considered in the differential diagnosis of cerebellar hypoplasia.

Suramin-induced weakness from hypophosphatemia and mitochondrial myopathy. Association of suramin with mitochondrial toxicity in humans

BACKGROUND

Suramin is an antiparasitic drug being evaluated as an antitumor compound. Suramin therapy commonly causes weakness and is known to cause neuropathy. Two potential causes of suramin-induced muscular weakness are described.

METHODS

Suramin was administered to 15 patients with advanced cancer as part of a Phase I study. Weekly dosing was adjusted to achieve mean plasma concentrations of 210 micrograms/ml.

RESULTS

Serum phosphate levels fell significantly (P < 0.0001) in all 15 patients on the 42nd day of treatment from a pretreatment average of 4.0 mg/dl (standard deviation [SD] +/- 0.37) to 3.0 mg/dl (SD +/- 0.20). Absolute hypophosphatemia developed in two patients with more prolonged suramin treatment due to Fanconi's syndrome. The patient who received the largest amount of suramin (19.2 g over 14 weeks) had severe proximal muscle weakness despite 6 weeks of effective phosphate repletion. A muscle biopsy was performed, which demonstrated markedly decreased cytochrome c oxidase activity by muscle histochemistry and biochemistry. Electron microscopy revealed subsarcolemmal collections of abnormal mitochondria. This mitochondrial myopathy resolved clinically 7 weeks after discontinuing suramin.

CONCLUSIONS

This report indicates that suramin is associated with hypophosphatemia of Fanconi's syndrome and a mitochondrial myopathy. The clinical combination of mitochondrial myopathy and Fanconi's syndrome is similar to descriptions of congenital mitochondrial cytochrome c oxidase deficiency of de Toni-Fanconi-Debré syndrome. These findings in humans correlate with the authors' in vitro observations that suramin causes toxic mitochondrial changes, indicating a mechanism of suramin's toxicity and possibly its antitumor effect.

A hypotonic infant with complete deficiencies of acid maltase and debrancher enzyme

Infantile acid maltase deficiency is an autosomal recessive disease that invariably leads to death in the first 2 years of life. Debrancher deficiency, also an autosomal recessive disease, however, carriers a slowly progressive course. We report a hypotonic infant with a typical clinical course of infantile acid maltase deficiency in whom biochemical investigation revealed complete deficiencies of both acid maltase and debrancher enzyme.

Clinical, metabolic, and genetic aspects of cytochrome C oxidase deficiency in Saguenay-Lac-Saint-Jean

Thirty-four children with lactic acidosis and Leigh encephalopathy due to cytochrome C oxidase (COX) deficiency distributed in 28 families have recently been identified in northeastern Quebec, particularly in the Saguenay-Lac-Saint-Jean (SLSJ) region. The segregation analysis was consistent with an autosomal recessive mode of inheritance. The incidence was estimated at 1/2,063 live births between 1979 and 1990, and the carrier rate was estimated at 1/23 inhabitants in SLSJ. In SLSJ, the places of origin of the COX-deficient children and their parents did not show a clustered nonuniform distribution. The genealogical reconstruction of 54 obligate carriers identified 26 ancestors common to all of them. Twenty-two were 17th-century Europeans, suggesting that the COX-deficient gene was introduced in the French-Canadian population by early settlers. These results support the hypothesis of a founder effect for COX deficiency in northeastern Quebec. Clinical findings are reported for 15 of these COX-deficient patients, age 6 mo to 11 years. Moderate developmental delay, hypotonia, ataxia, strabismus, and mild facial dysmorphism were frequent. Eleven children died in episodes of fulminant metabolic acidosis. The patients had elevated blood and cerebrospinal fluid lactate levels, decreased blood bicarbonate levels, and normal blood pH. Leigh disease and microvesicular steatosis of the liver were present in all affected patients for whom postmortem examination was performed. This biochemically uniform group of patients showed a wide range of clinical severity.

Familial hypotonia of childhood caused by isolated 3-methylcrotonyl-coenzyme A carboxylase deficiency

Hypotonia was the initial symptom in four siblings from a nonconsanguineous Tunisian-Jewish family. Plasma carnitine was severely deficient, and urinary organic acid analysis revealed increased excretion of 3-hydroxyisovaleric acid and 3-methylcrotonylglycine. 3-Methylcrotonyl-coenzyme A carboxylase activity was reduced in skin fibroblasts; pyruvate carboxylase and serum biotinidase activities were normal. We conclude that 3-methylcrotonyl-coenzyme A carboxylase deficiency should be added to the list of metabolic causes of familial hypotonia of childhood.

Defects of the mitochondrial respiratory chain complexes in three pediatric cases with hypotonia and cardiac involvement

Three children displaying hypotonia, cardiac involvement and defects of the mitochondrial respiratory chain complexes are reported. The first case showed severe neonatal hypotonia, failure to thrive, hepatomegaly, dilation of the right cardiac cavities, profound lactic acidosis and amino aciduria. The boy died at the age of 7 weeks. In the second case hypotonia, severe cardiomyopathy, cyclic neutropenia, lactic acidosis and 3-methylglutaconic aciduria occurred. The boy died at the age of 27 months. The third case presented at the age of 16 months as an acute hypokinetic hypertrophic cardiomyopathy with transient hypotonia and mild lactic acidosis. Spontaneous clinical remission occurred. In all cases muscle biopsy was performed. Morphological studies failed to show ragged-red fibers but there was lipid storage myopathy and decreased cytochrome c oxidase activity. Biochemical studies confirmed the cytochrome c oxidase deficiency in muscle in all cases. It was associated with complex I III deficiency in case 1 and with severe deficits of all respiratory chain complexes in case 2. Post-mortem studies in case 1 indicated that complex IV was reduced in the liver but not in the heart and quantitative analysis of mtDNA revealed a depletion in muscle. Cases 1 and 2 shared some clinical features with fatal infantile myopathy associated with cytochrome c oxidase deficiency, while case 3 displayed a very unusual clinical presentation. The histochemical enzyme reaction of cytochrome c oxidase is useful for the diagnosis of mitochondrial myopathy because ragged-red fibers may be lacking. Finally, biochemical measurement of the different mitochondrial respiratory chain complexes is required because multiple defects are frequent and occasionally related to mtDNA depletion.

[A case of adult onset phosphoglucomutase deficiency]

A case of 38-year-old male with adult onset phosphoglucomutase (PGM) deficiency was reported. The patient was admitted at Kawamura Hospital (Gifu City) for evaluation of easy fatiguability and exercise-induced weakness of the extremities since he was 20 years old. Physical examination revealed moderate muscle weakness, wasting of extremities, bilateral clubbed fingers and hypoesthesia of distal portion of extremities. Fasting plasma glucose was low (58 mg/dl). Venous concentration of lactate failed to rise after an ischemic forearm exercise test. An epinephrine tolerance test revealed hyperglycemic response. Studies of anaerobic glycolysis in vitro using muscle homogenates with the substrate between glucose-1-phosphate and glucose-6-phosphate showed decreased lactate production. Direct assay of individual muscle glycolytic enzymes demonstrated reduction of PGM activity (15% of normal, n = 12). Biopsy study with PAS staining of quadriceps femoris muscle demonstrated small amount of deeply staining glycogen in subsarcolemmal area. Electron microscopic examination revealed muscle destruction with small amount of glycogen in subsarcolemmal and intermyofibrillar spaces. Sural nerve biopsy showed degeneration of myelinated and unmyelinated fibers but there was no apparent accumulation of glycogen. From the clinical, biochemical and histopathological evidences, the patient might be a rare case of adult onset PGM deficiency.

Lipid storage myopathy in multiple acyl-CoA dehydrogenase deficiency: an adult case

A 25-year-old woman had been complaining of episodes of muscle weakness, nausea and vomiting since the age of 10. Muscle biopsy showed free fatty acid accumulation and mitochondrial abnormalities. Mitochondrial DNA appeared to be normal at Southern analysis. Biochemical investigations demonstrated: glutaric aciduria type II, decreased levels of carnitine in liver and values at the lower level of normal in muscle, increased muscle carnitine palmitoyl transferase activity, partial cytochrome c oxidase and succinate cytochrome reductase deficiency in muscle homogenate. In isolated muscle mitochondria, cytochromes aa3, b and c were partially decreased, butyryl-CoA dehydrogenase and palmitoyl-CoA dehydrogenase activities were 10 and 54% of the normal, respectively. Muscle cell cultures did not show lipid storage. Low-lipid diet reduced critical episodes and lipid storage in muscle biopsy.

Deficiency of the alpha and beta subunits of pyruvate dehydrogenase in a patient with lactic acidosis and unexpected sudden death

An infant with moderate muscular hypotonia and congenital lactic acidosis died suddenly at the age of 3 months. Autopsy revealed no abnormalities responsible for this unexpected death. Measurement of mitochondrial enzymes involved in energy production indicated a severely decreased total pyruvate dehydrogenase complex (PDHC) activity in muscle tissue (0.23 nmoles x min-1 x mg protein-1, control range 2.8-8.7) and moderately decreased PDHC activity in fibroblasts (0.27 nmoles x min-1 x mg protein-1, control range 0.37-2.32). The activity of the first component E1 (pyruvate dehydrogenase) in muscle tissue was 10 times lower than that of controls (0.008 nmoles x min-1 x mg protein-1, control range 0.10-0.25). The activities of dihydrolipoyl dehydrogenase (E3) and various other mitochondrial enzymes were normal. Immunochemical analysis in skeletal muscle tissue and fibroblasts demonstrated a decrease in the amount of the alpha and beta subunits of E1. The features of this patient are compared with those of other patients reported in the literature with immunochemically confirmed combined E1 alpha and beta deficiency.

[Mitochondrial encephalomyopathy (focal cytochrome c oxidase deficiency) with transient episodes of muscle weakness and elevation of serum creatine kinase activity]

A 17-year-old boy who had mitochondrial encephalomyopathy with focal deficiency of cytochrome c oxidase (CCO) activity is described. He experienced 3 episodes of muscle weakness, fatigability, nausea, vomiting and concomitant increase of serum creatine kinase activity, at the age of 13, 15 and 17 years. During interval there was no muscle weakness and the serum creatine kinase activity was within normal range. Increased levels of lactic acid and pyruvic acid were observed in the blood and cerebrospinal fluid. After an aerobic exercise test, lactic acid and pyruvic acid in the blood increased to an abnormally high level, and the arterial blood became acidic (pH 7.297). On EEG, occasional intermittent irregular theta activities were observed in the anterior region, but there were no abnormalities on CT and MRI in the central nervous system. In the biopsied muscle, ragged-red fibers comprised 20% on modified Gomori-trichrome staining and a number of fibers with no CCO activity were scattered throughout. The CCO activity in the mitochondria isolated from the biopsied muscle was reduced to 49.2 nmol/min/mg protein (normal range 144.7-355.8), while other mitochondrial enzyme activities in the electron transport system were normal. From these data, the patient was considered to have a unique form of mitochondrial encephalomyopathy. By the administration of a large amount of coenzyme Q10, episodes of muscle weakness and nausea, and an increase of lactic acid and pyruvic acid in the blood after aerobic exercise test were no longer observed.

Effects of electrical muscle stimulation combined with voluntary contractions after knee ligament surgery

The aim of the present study is to compare the effect of electrical muscle stimulation combined with voluntary muscle contractions with a program only with voluntary muscle contractions during immobilization in casts after anterior cruciate ligament surgery. Twenty-three patients, 7 women and 16 men with a mean age of 28 yr, were randomized into two groups: an experimental group (13 patients) and a control group (10 patients). Post-operatively, the patients were immobilized for 3 wk in a full leg cast with the knee flexed at an angle of 20 degrees to 30 degrees and then in a knee cast for another 3 wk. All patients had a standard program with quadriceps muscle contractions. In addition, the experimental group received electrical stimulation of the quadriceps muscle 4 X 10 min, 3 times.wk-1, at a frequency of 30 Hz. During each stimulation, the patients were requested to contract the quadriceps muscle voluntarily as well. When pre-operative measurements were compared with those at the end of the immobilization period (6 wk after the operation), a significantly larger reduction in the knee extension isometric muscle strength was found for the control group than for the experimental group. In comparisons of the data of the male subjects only, this difference was still seen to be significant. The cross-sectional area of the quadriceps muscle measured with computed tomography was significantly less reduced during the immobilization period in the experimental group than in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Infantile glycerol kinase deficiency--a condition requiring prompt identification. Clinical, biochemical, and morphological findings in two cases

Infantile glycerol kinase deficiency (GKD) is an X-linked genetic disease characterized clinically by adrenal insufficiency and muscular dystrophy. The enzyme defect leads to increased levels of glycerol in blood and urine, which can be used for diagnosis. Without recognition of this condition, the chances for life-saving steroid treatment and for genetic counselling are missed. We report clinical, endocrinological, biochemical, and morphological findings in two non-related boys. One of them died in early infancy. The other is thriving at the age of 2 years although he is suffering from a myopathy not distinguishable from Duchenne muscular dystrophy. We discuss when to suspect and how to confirm the diagnosis of infantile GKD, and under what precautions the condition is detectable by commonly used screening procedures for inborn errors of metabolism.

Foamy myocardial transformation in a child with a disturbed respiratory chain

A female infant presented with signs of general muscle hypotonia and increasing hypertrophy of the heart muscle. There was a constant lactic acidosis worsened after glucose intake. Serum lactate levels were increased up to 6.7 mmol/l. Serum alanine levels reached maximum concentrations of 2,800 mumol/l. The patient died after sudden cardiac arrest at 22 months of age. Histology of the heart showed the pattern of foamy myocardial transformation with accumulation of mitochondria and an increased glycogen content. Biochemical analysis of the skeletal muscle and the heart demonstrated signs of a disturbed respiratory chain. The content of cytochrome aa3 protein was decreased in skeletal muscle and heart mitochondria. It is suggested that respiratory chain defects may be the cause of foamy myocardial transformation of the heart.

Muscular abnormalities in children with muscular hypotonia and cerebral damage

Forty children with hypotonia and non progressive cerebral impairment were observed. In all cases muscle morpho-histometric and ultrastructural studies were performed, in 13 cases muscular acetylcholinesterase study was carried out. The Authors pointed out the high frequency (92% of cases) of muscle abnormalities: histochemical alteration of fibre type distribution (type 1 or type 2 fibres prevalence, type 2C persistence), diameter change (hypertrophy or hypotrophy of the fibres). In 37.5% of the cases, randomly distributed, were also present myofibrillar degeneration, Z band streaming, desalignment or marked destructuration of the sarcomeres. The muscular acetylcholinesterase study showed the same anomalous pattern of molecular forms (11 out of 13 cases), with increase of light (6S, 4S) and disappearance of heavy (16S) and medium forms (13S, 10S), without significant change of enzymatic activity. The possible alterated influence of CNS on muscle fibre differentiation and growth because of abnormal neural control is discussed. This hypothesis even if could be related with abnormal fibre typing and diameter, do not seem to explain the ultrastructural and biochemical abnormalities observed.

Deficient fumarase activity in an infant with fumaricacidemia and its distribution between the different forms of the enzyme seen on isoelectric focusing

A male infant, whose parents were first cousins, presented at 6 mo of age with hypotonia, microcephaly, and delayed development. He was found to have large amounts of fumaric and succinic acids present in the urine. In lysed cultured skin-fibroblast preparations, the activity of fumarase was found to be 22.7% of that in controls. Cell fractionation by homogenization and by digitonin treatment indicated that the residual activity in the cells of the patient was primarily located in the mitochondrial fraction rather than in the cytosolic fraction. Isoelectric focusing of fibroblast extracts showed that six bands of fumarase activity were discernible in control cell lines, two of them cytosolic with pI's of 5.53 and 5.60 and four of them mitochondrial with a pI of 5.65-6.8. In contrast, isoelectric focusing of fibroblast extracts from the fumarase-deficient patient showed only a single band of activity with a pI corresponding to the mitochondrial type seen in the controls. Immunoprecipitation of proteins with rabbit antifumarase antibody in (35S)-methionine-labeled fibroblasts indicated that a protein of correct size (Mr = 44,000 daltons) corresponding to fumarase was synthesized in similar amounts in both the patients and controls. It is proposed that in the patient's cells a single active species of fumarase that is mitochondrial in location is synthesized. Since it is known that mitochondrial and cytosolic fumarases are encoded by the same gene but differ slightly in amino acid sequence, it is possible that a point mutation might explain these findings.

Benign congenital hypotonia with uniform type 1 fibers and aspecific ultrastructural changes in the muscle: a case with esophagus involvement

We report the case of a child with congenital neuromuscular disease characterized by neonatal onset of symptoms, a floppy syndrome with marked weakness of facial muscles, palsy of the velum pendulum and hypomotility of the esophagus. EMG was inconclusive. Serum enzyme levels were within the normal range. Muscle biopsy specimen showed uniform type 1 fibers, smallness of the occasionally observed type 2 fibers and slight ultrastructural changes in many fibers. On the basis of the clinical and morphological features we have included the present case among the group of non-progressive congenital neuromuscular diseases.

Defects in citric acid cycle and the electron transport chain in progressive poliodystrophy

We will present 8 children with progressive infantile or juvenile poliodystrophy (Alpers' disease), associated with a defect in pyruvate metabolism. Laboratory studies showed elevated levels of lactate in CSF and, in 4 children, elevated levels in serum. Histopathologic studies revealed lipid storage in liver and/or muscle tissue, sometimes myopathy with abnormal mitochondria and slight axonal degeneration in the peripheral nerve. Autopsy showed the characteristics of progressive poliodystrophy with degeneration and loss of neurons. Electron microscopy of cerebral cortex showed no mitochondrial abnormalities in neurons or astroglia. Biochemical studies in muscle and/or liver and/or cerebral tissue showed different deficiencies in pyruvate metabolism: in the pyruvate dehydrogenase complex, in the second part of the citric acid cycle (after the oxoglutarate dehydrogenase complex), in the NADH oxidation, in cytochrome aa3 and in pyruvate carboxylase.

[Mitochondrial myopathy associated with cytochrome oxidase deficiency]

Six patients are described in whom a deficiency of cytochrome oxidase in muscle tissue was found. Four patients suffered from the syndrome of 'floppy babies' with profound hypotonia, muscle weakness and failure to thrive. They died within the first 6 months of life. Two patients suffered from Leigh's and Alpers' syndrome, respectively. In all patients lactate level was elevated in one or more body fluids, whereas in 4 patients a generalized amino-aciduria was found. With electronmicroscopy structurally abnormal mitochondria were seen in the muscle of 5 out of the 6 patients.

Myopathy due to juvenile acid maltase deficiency affecting exclusively the type I fibres

The clinical and laboratory findings of a patient with juvenile acid maltase deficiency are presented. The patient died from respiratory muscle weakness at age 31 years. Muscle biopsy shortly prior to his death showed remarkable vacuolation affecting exclusively type I fibres and mild myopathic changes of both types of muscle fibres, while the muscle biopsy at age 26 years had shown no evidence of acid maltase deficiency.

An unusual form of arylsulfatase A deficiency combined with sulfatide-excretion and a normal sulfatide-loading

A 7-year-old girl who showed retarded psychomotor development and generalized hypotonia without any signs of progression is described. Marked deficiency of arylsulfatase A activity in leukocytes and fibroblasts was observed. Both parents showed activity in cultured fibroblasts within the heterozygote-normal range. Cerebroside-sulfatase activity was absent in cultured fibroblasts from the patient. Urinary analyses revealed a pathologically increased sulfatide excretion. Normal sensory nerve conduction velocity was found, but no metachromatic material was found in a sural nerve biopsy. Loading of the patient's fibroblasts with sulfatides resulted in normal uptake and normal degradation.

Mitochondrial cytochrome deficiency presenting as a myopathy with hypotonia, external ophthalmoplegia, and lactic acidosis in an infant and as fatal hepatopathy in a second cousin

Fatal infantile mitochondrial myopathy with lactic acidosis, morphologically abnormal mitochondria, deficient cytochromes aa3 and b, and a Fanconi-like aminoaciduria has been described. We report two infants, second cousins, with a similar fatal mitochondrial disorder, the cytochrome deficiency limited to skeletal muscle in one child and to liver in the other. The first child at 3 months of age had weight loss, hypotonia, external ophthalmoplegia, and a severe lactic acidosis with a high lactate/pyruvate ratio. Electron microscopy of muscle showed marked proliferation of enlarged mitochondria, many containing concentric rings of cristae. In skeletal muscle mitochondria, cytochromes aa3 and b were not detectable but cytochrome cc was found to be normal by spectroscopy. Cytochrome c oxidase activity was less than 1% of normal. Mitochondria from kidney, liver, heart, lung, and brain examined postmortem had normal cytochromes and preserved cytochrome c oxidase activity. The second cousin at 5 months of age had weight loss and hepatomegaly but no systemic lactic acidosis. Liver biopsy showed hepatocytes packed with enlarged mitochondria. The liver mitochondria showed deficient cytochromes aa3 and b postmortem, and cytochrome c oxidase activity was less than 10% of normal. Kidney mitochondria had normal cytochromes. Muscles was not studied. The mitochondrial abnormality in the two cousins presumably is related. Unexplained are the mode of genetic transmission or environmental exposure and the apparent involvement of a single different organ in each child.

Benign infantile mitochondrial myopathy due to reversible cytochrome c oxidase deficiency

A 2-week-old boy had profound generalized weakness, hypotonia, hyporeflexia, macroglossia, and severe lactic acidosis. The infant improved spontaneously: he held his head at 4 1/2 months, rolled over at 7 months, and walked by 16 months. At 33 months of age, he had mild proximal weakness. Macroglossia disappeared by age 4 months. Blood lactic acid declined steadily and was normal by 14 months of age. Histochemical and ultrastructural studies of muscle biopsy specimens obtained at 1 and 7 months of age showed excessive mitochondria, lipid, and glycogen; a third biopsy at age 36 months showed only atrophy of scattered fibers. Cytochrome c oxidase stain was positive in fewer than 5% of fibers in the first biopsy, in approximately 60% of fibers in the second biopsy, and in all fibers in the third biopsy. Biochemical analysis showed an isolated defect of cytochrome c oxidase activity, which was only 8% of the lowest control level in the first biopsy; the activity increased to 47% in the second biopsy and was higher than normal in the third. In contrast to that in the fatal infantile form of cytochrome c oxidase deficiency, the enzyme defect in this condition is reversible. The biochemical basis for this difference remains to be explained.

Enzymologic studies and therapy of Leigh's disease associated with pyruvate decarboxylase deficiency

An 11-month-old boy with muscle hypotonia and neurologic deteriorations had lactic acidosis, pyruvic acidemia and alaninemia due to deficiency of the pyruvate dehydrogenase complex in his platelets and of pyruvate decarboxylase in his muscle. When placed on a low carbohydrate-high fat diet for 6 months, his blood levels of lactate and pyruvate became nearly normal, but his cerebrospinal fluid levels of lactate and pyruvate remained high. Despite this dietary therapy, neurologic deterioration progressed slowly. He died of pneumonia after artificial respiration for 3 wk. At autopsy, extensive symmetric lesions were found in the brain including proliferation of capillaries and gliosis in the brain stem and diffuse demyelination in the white matter. These lesions were consistent with those observed in Leigh's disease. The activities of the pyruvate dehydrogenase complex and pyruvate decarboxylase in various tissues obtained at autopsy were less than 10% of control values; however, the activities of pyruvate carboxylase and alpha-ketoglutarate decarboxylase were within the normal limits. This patient with Leigh's disease had an isolated deficiency of pyruvate decarboxylase in various tissues.

Lipid storage myopathy in infantile Pompe's disease

An infant died at 8 months of age with a history of developmental regression, hypotonia, severe weakness, cardiomegaly, congestive heart failure, and hepatomegaly. A diagnosis of Pompe's disease (glycogenosis type II) was established by muscle biopsy at 5 months of age. Vacuolar myopathy involved muscle fibers of histochemical type I more than type II. Many vacuoles were filled with glycogen. In addition, increased amounts of neutral lipid were demonstrated by oil red O stain, electron microscopy, and quantitative analysis. Acid alpha-1,4-glucosidase activity was demonstrated to be deficient. Biochemical studies failed to determine the cause of the lipid accumulation, but demonstrated a low total concentration of carnitine in the muscle (6.37 nmole/mg of protein), associated with elevated activities of carnitine palmityl-transferase and palmityl-coenzyme A dehydrogenase. Palmityl-coenzyme A synthetase activity was in the normal range.

X-linked recessive congenital muscle fiber hypotrophy with central nuclei: abnormalities of growth and adenylate cyclase in muscle tissue cultures

Muscle cells in cultures established from biopsy specimens of two children with an infantile-fatal form of X-linked recessive muscle fiber smallness with central nuclei showed an unusual ability to proliferate through numerous passages. Ultrastructurally, the cultured muscle fibers appeared very immature even after several weeks. The nuclei were large, the number of ribosomes was greatly increased, the myofibrils remained unstriated, and glycogen was accumulated in large lakes. The plasmalemma bound concanavalin A, alpha-bungarotoxin, and ruthenium red normally, but with tannic acid it did not show the dark binding of mature fibers. Biochemically, in the cultured muscle fibers, beta-adrenergic receptors were quantitatively normal. The level of adenylate cyclase in membranes was less than in cultured normal muscle; this defect could be responsible for impaired control mechanisms resulting in the other abnormalities observed.