The G526R glycyl-tRNA synthetase gene mutation in distal hereditary motor neuropathy type V

BACKGROUND

Distal hereditary motor neuropathy (dHMN) or distal spinal muscular atrophy (dSMA) is a heterogeneous group of disorders characterized almost exclusively by degeneration of motor nerve fibers, predominantly in the distal part of the limbs. One subtype, dHMN type V (dHMN-V), is transmitted by autosomal dominant inheritance and predominantly involves the hands. It is allelic with Charcot-Marie-Tooth disease 2D (CMT2D), in which a similar phenotype is associated with sensory signs. Missense mutations in the glycyl-tRNA synthetase (GARS) gene have been recently reported in families with either dHMN-V, CMT2D, or both.

METHODS

The authors searched for GARS mutations in eight dHMN-V families.

RESULTS

The authors found the G526R missense mutation in three families (16 patients) of Algerian Sephardic Jewish origin. All patients shared a common disease haplotype, suggestive of a founder effect. The clinical phenotype consists of a slowly progressive, purely motor distal neuropathy. It starts in the hands in most patients, but also in both distal upper and lower limbs or in distal lower limbs alone. The age at onset in symptomatic individuals was between the second to fourth decades, but four mutation carriers were still asymptomatic, two of whom were already age 49 years. Electrophysiology showed that the motor fibers of the median nerve were the most affected in upper limbs. Sensory nerve action potentials were normal.

CONCLUSIONS

The age at onset of patients with the G526R mutation in the GARS gene varied widely, but the clinical and electrophysiologic presentation was uniform and progressed slowly. Glycyl-tRNA synthetase mutations are a frequent cause of familial distal hereditary motor neuropathy type V but, because of the reduced penetrance of the disease, could also account for isolated cases.

A gene for an autosomal recessive lower motor neuron disease with childhood onset maps to 1p36

OBJECTIVE

To describe the clinical features of a novel variant of autosomal recessive lower motor neuron disease (LMND) with childhood onset and to map the disease-causing gene.

METHODS

The authors performed a clinical study in a large consanguineous African family. After linkage exclusion to SMN1 and SOD1 loci, they performed a genome-wide linkage analysis to map the underlying genetic defect.

RESULTS

This novel variant of LMND with childhood onset and autosomal recessive mode of inheritance is characterized by a progressive symmetric and generalized involvement of the musculature. Four of the five affected patients had muscle weakness since age 3, strongly worsening during childhood and leading to generalized tetraplegia in adulthood. Genetic analyses using homozygosity mapping strategy assigned this progressive generalized LMND locus to an interval of 3.9 cM (or 1.5 megabases) on chromosome 1p36, between loci D1S508 and D1S2633 (Z(max) = 3.79 at theta = 0.00 at locus D1S253). This region encloses 27 candidate genes.

CONCLUSION

Genetic mapping of a novel rare phenotype of lower motor neuron disease opens the way toward the identification of a new gene involved in motor neuron degeneration, located in the 1p36 chromosomal region.

'Cap myopathy': case report of a family

We report the observation of an 18-year-old girl, whose clinical presentation was very suggestive of a congenital myopathy with neonatal onset. A congenital myopathy had been already diagnosed in her brother and in addition her half-cousin died diagnosed with a severe nemaline myopathy at age 4 years. A muscle biopsy performed on both siblings revealed histological and ultrastructural features of 'cap myopathy'. This case report suggests that 'cap myopathy' and some cases of nemaline myopathy with neonatal onset might be two phenotypic expressions of the same genetic disorder. These two entities could therefore, perhaps, be regarded as 'Z-line disorders' possibly caused by defective myofibrillogenesis.

Congenital myasthenic syndrome due to rapsyn deficiency: three cases with arthrogryposis and bulbar symptoms

We report the cases of 3 children with postsynaptic congenital myasthenic syndrome with acetylcholine receptor deficiency due to rapsyn deficiency. Symptoms began at the neonatal period with hypotonia, arthrogryposis, bulbar symptoms, and respiratory distress. Two of the 3 children needed tracheostomy and gastrostomy. Electromyograms showed a decremental response to repetitive stimulation. Muscle biopsies were normal or showed type I fiber preponderance. Genetic studies identified mutations in the rapsyn gene (RAPSN). The 3 patients were heterozygous for N88 K and a second mutation (either Y86X, 1083_1084 dupCT or IVS4-2 A > G). The patients responded favorably to anticholinesterase treatment, with a clear improvement of clinical symptoms, especially the bulbar symptoms of apneas and swallowing disturbances. This paper underlines the importance of anticholinesterase medication in patients with congenital myasthenic syndrome due to rapsyn deficiency.

Syndromes myasthéniques congénitaux dus à des mutations du gène de la rapsyne

Congenital myasthenic syndromes (CMS) are genetic diseases characterized by dysfunctional neuromuscular transmission and usually start during the neonatal period. Most are due to postsynaptic abnormalities, specifically to mutations in the acetylcholine receptor (AChR) genes. In 2002, the group of A Engel reported the first cases of CMS with mutations in the gene coding rapsyn, a postsynaptic molecule which stabilizes AChR aggregates at the neuromuscular junction. Since this first publication, more than 30 other cases, including six in France, have been reported. Study of these published cases allows us to distinguish three classes of phenotypes: 1) severe neonatal cases; 2) more benign cases, starting during infancy; 3) cases with facial malformations, involving Jewish patients originating from the Near-East. Comparison of the observations of other groups with our own has led us to the following conclusions: the N88K mutation is frequent (homozygous in 50% of cases); besides the N88K mutation, the second mutation varies considerably; heterozygous allelic cases (N88K + another mutation) are severe; there is probably a founder effect in the European population. There is phenotypic variability in the homozygous N88K cases, with benign cases and severe cases of early expression. A Engel and colleagues report that the seven cases of benign CMS with facial malformation, previously described in the Jewish population of Iraq and Iran, were caused by mutation in the promoter region of the rapsyn gene.

Spinal penetration index: new three-dimensional quantified reference for lordoscoliosis and other spinal deformities

We studied and conceptually analyzed a retrospective case series of patients with airway compression due to an anterior vertebral body protrusion. The goal was to describe the pathology, methods of management, and a new concept for quantifying deformity. Case reports have been published on this pathology, but there has been no case series to date. In this study 18 patients with ages ranging from 7.3 to 18.0 years had thoracic lordoscoliosis due to a variety of etiologies; most ( n = 10) had a neuromuscular disorder. Following treatment, which most commonly was anterior subtotal subperiosteal vertebral body resection followed by posterior instrumentation and arthrodesis, atelectasia disappeared and any abnormal blood gases normalized; however, the effect on vital capacity was variable. Based on computed tomographic studies, the concept of the deformity as an endothoracic vertebral hump was developed and quantified. Study of this series of patients with compression of the airway due to vertebral body protrusion into the thorax provided the opportunity to describe treatment, define a new concept (the spinal penetration index), and make general recommendations about the management of both the endothoracic hump and the exothoracic rib hump.

[Thoracic scoliosis: exothoracic and endothoracic deformations and the spinal penetration index]

PURPOSE OF THE STUDY

We reviewed retrospectively our patients with thoracic lordoscoliosis and conducted a conceptual analysis of the patients with airway compression and atelectasia due to anterior protrusion of the vertebral bodies in order to describe the pathological conditions involved and the management methods used. Our goal was to develop a new concept for quantifying thoracic deformation. The individual cases discussed here have been reported earlier, but this is the first series analysis to date.

MATERIAL AND METHODS

Eighteen patients, aged 7.3 to 18 years, with thoracic lordoscoliosis due to a variety of causes, mostly neuromuscular disorders (12 cases), are described. Most patients were treated by anterior subtotal periosteal resection of the vertebral body followed by posterior instrumentation and arthrodesis.

RESULTS

Atelectasia disappeared with a normalization of blood gases but the effect was variable on vital capacity. The analysis of the CT studies led to the concept of spinal deformity as an endothoracic deformation resulting from protrusion of the vertebral body into the thorax, the endothoracic vertebral hump. This concept was developed and quantified leading to the definition of a new index: the spinal penetration index. The spinal penetration index was obtained by tracing a line tangent to the posterior curve of the concave and convex ribs on each CT slice to determine a relationship between the real thoracic surface and theoretical thoracic surface measured with this tangent and the circumference of the thoracic cage. The index was expressed as a percent of the endothoracic surface occupied by the protruding veterbral body and the associated ribs. Calculated for each successive CT slice for the entire height of the thorax yielded a spinal penetration index quantifying the thoracic volume occupied by the spine. For the control population, we used CT series of the thorax obtained to search for pulmonary metastases in patients with malignant tumors. This gave a theoretical volume of 8 to 10% occupied by the spine in normal subjects. In our patients with lordoscoliotic deformations we obtained real volumes of 15, 20 and even 50%.

DISCUSSION

The spinal penetration index is an important morphological index of thoracic anatomy that measures the real volume of the functional thoracic cavities and which must be differentiated from vital capacity which measures both volume and function. This index can be used for pre- post-operative comparisons and constitutes a first step in 3-D assessment of thoracic spine deformations. It can also be used to classify spinal deformations and to make general recommendations concerning the management of both endothoracic humps and exothoracic rib humps.

Congenital muscular dystrophy with primary partial laminin alpha2 chain deficiency: molecular study

The authors report a case of congenital muscular dystrophy with mild nonprogressive muscle weakness, white matter hypodensity, and absence of the laminin alpha2 chain in muscle fibers with two antibodies, but not with four others. They identified mutations in LAMA2, which explain the partial laminin alpha2 deficiency. Analysis of this case and two others allows us to refine the epitopes of two of the commercial antibodies, and illustrate the importance of using antibodies directed against different domains of the protein.

[Andermann syndrome in an Algerian family: suggestion of phenotype and genetic homogeneity]

Andermann syndrome or Agenesis of the Corpus Callosum with Polyneuropathy (MIM 218000) is an autosomal recessive disease almost exclusively found in Québec. Only few cases have been reported in other populations. The locus for Andermann syndrome was assigned to chromosome 15q13-q15 in French Canadian families. We performed a haplotype analysis with two markers of this chromosomal region in an Algerian consanguineous family with two affected sibs. The children were homozygous for both markers, suggesting genetic homogeneity in Andermann syndrome.

Brown-Vialetto-Van Laere syndrome in a large inbred Lebanese family: confirmation of autosomal recessive inheritance?

Brown-Vialetto-Van Laere syndrome or pontobulbar palsy with deafness is a rare disorder characterized by bilateral nerve deafness, a variety of cranial nerve disorders usually involving the motor components of the 7th and 9th to 12th cranial nerves, and less commonly an involvement of spinal motor nerves and upper motor neurons. Familial and sporadic cases have been reported. Based on particular evidence, autosomal recessive, autosomal dominant, and X-linked inheritance, as well as autoimmune origin have been considered. We report on a large inbred Lebanese family with four patients of both sexes, strongly suggesting autosomal recessive inheritance.

Homogeneous phenotype of the gypsy limb-girdle MD with the gamma-sarcoglycan C283Y mutation

OBJECTIVE

To characterize the clinical phenotype of LGMD2C in gypsies.

BACKGROUND

Limb-girdle muscular dystrophy (LGMD) in gypsies of Western Europe is caused by a homozygous C283Y mutation on the same haplotype, suggesting a founder effect.

METHODS

We performed clinical, laboratory, and muscle imaging studies of 40 patients.

RESULTS

Mean age at onset was 5.3 years. One half of the patients had loss of ambulation by the age of 12; 13% still could walk after age 16. Calf hypertrophy, scapular winging, macroglossia, and lumbar hyperlordosis were common. Girdle, trunk, and proximal limb flexor muscles had earlier and more severe involvement. Cardiomyopathy was not observed. Five patients in the third decade of life required mechanical ventilation. Scoliosis was common in the nonambulatory stage.

CONCLUSIONS

LGMD2C in gypsy patients with C283Y mutation presents a rather homogeneous phenotype, characterized by an initial Duchenne-like progressive course followed by a more prolonged survival rate possibly due to the absence of early respiratory impairment and cardiac failure.

Genetic heterogeneity of congenital muscular dystrophy with rigid spine syndrome

Rigid spine syndrome is a neuromuscular disorder characterised by early rigidity of the spine due to axial muscle contractures, generally associated with muscle weakness, limb-joint contractures, and often respiratory failure. This phenotype may be associated with several muscular diseases. In cases of merosin-positive congenital muscular dystrophies (CMD) with rigid spine syndrome, we have recently identified a new locus (RSMD1) on chromosome 1p35-36. In the present study, we report the clinical, morphological and genetic analysis of other patients affected by a CMD with rigid spine syndrome from nine consanguineous families. Homozygosity mapping showed that the disease was linked to RSMD1 in one of the nine families. The other families were excluded from RSMD1, and the patients presented highly variable phenotypes suggesting the involvement of more than one gene defect in rigid spine syndrome. Nevertheless, a subgroup of patients who never walked, and had very early rigidity of the spine and scoliosis, may be considered for further genetic analysis.

[Respiratory problems in severe scoliosis]

In kyphoscoliosis restrictive ventilatory defect occurs. In idiopathic scoliosis vital capacity failure is significantly correlated with Cobb angle, vertebral rotation, and thoracic lordosis. Maximum voluntary ventilation is the most affected measurement. Forced expiratory volume in 1 second is reduced. Residual volume remains longtime normal. Hypoxemia due to decrease of diffusing capacity occurs, with initially reflex hyperventilation hypocapnia, and secondary hypercapnia. Pulmonary hypertension and cor pulmonale is related to hypoventilation and hypoxia. The lung situated on the concave side of the scoliosis curve shows a more functional derangement. Ventilatory pattern consists of low tidal volume and high respiratory rate with increase of ventilatory work. Scoliosis that appears in the earlier stage of the life has the worst respiratory prognosis (before 5 years of age) with impairement of lung and thoracic growth. To stimulate pulmonary and thoracic growth, intermittent ventilatory assistance by pressure preset ventilator should be performed as soon as possible and pursued up to 8 years of age, at least, more if necessity. In over 60 degrees angle idiopathic scoliosis, respiratory failure appears after 40 to 50 years of age. Non invasive ventilatory assistance with preset pressure ventilator by oral way in moderate cases and nocturnal nasal ventilation by volume ventilator or inspiratory assistance ventilator, in the most severe cases are efficient. In very severe and acute respiratory insufficiency (scoliosis over 90 degrees) ventilation by intubation then tractheostomy may be required. Earlier orthopedic management and surgical procedure to correct and stabilize spinal deformities is the best to prevent respiratory insufficiency. For scoliosis below 60 degrees, post operative pulmonary complications are very low, with no requirement of post operative ventilatory support. In very severe respiratory insufficiency treatment of respiratory failure precedes, and follows, orthotic treatment and surgical procedures; it shouldle pursued afterwards.

Allele-specific amplification for the diagnosis of autosomal recessive spinal muscular atrophy

The SMN1 gene is homozygously deleted for at least exon 7, interrupted or converted to a non-functional telomeric copy in most cases of proximal spinal muscular atrophies. The presence of a pseudogene hampers direct detection of the exon 7 deletion. We describe a method for the detection of the of exon 7 deletion, based on the amplification refractory mutation system (ARMS), in a multiplex PCR with fluorescent-labelled primers. The gene and pseudogene amplification products differ in the dye bound and in their size, which allows distinction of both products on electrophoresis. The pseudogene is used as an internal control, and this method gives a clear and specific pattern for the patients. Amplification is achieved with 30 cycles, and specificity is retained up to 40 cycles.

PCR based mutation screening of the laminin alpha2 chain gene (LAMA2): application to prenatal diagnosis and search for founder effects in congenital muscular dystrophy

Classical congenital muscular dystrophy with merosin deficiency is caused by mutations in the laminin alpha2 chain gene (LAMA2). Extended sequencing of the introns flanking the 64 LAMA2 exons was carried out and, based on these sequences, oligonucleotide primers were designed to amplify the coding region of each exon separately. By PCR-SSCP analysis, we identified eight new mutations in nine families originating from various countries. All induced a premature truncation of the protein, either in the short arm or in the globular C-terminal domain. A 2 bp deletion in exon 13, 2098delAG, was found in three French non-consanguineous families and a nonsense mutation of exon 20, Cys967stop, in two other non-consanguineous families originating from Italy. Determination of rare intragenic polymorphisms permitted us to show evidence of founder effects for these two mutations suggesting a remote degree of consanguinity between the families. Other, more frequent polymorphisms, G to A 1905 (exon 12), A to G 2848 (exon 19), A to G 5551 (exon 37), and G to A 6286 (exon 42), were used as intragenic markers for prenatal diagnosis. This study provides valuable methods for determining the molecular defects in LAMA2 causing merosin deficient congenital muscular dystrophy.

Congenital muscular dystrophy: use of brain MR imaging findings to predict merosin deficiency

PURPOSE

To evaluate the brain magnetic resonance (MR) imaging findings in patients with the "classic" form of congenital muscular dystrophy (patients with normal intelligence) in relation to the absence of merosin, a recently identified molecular component in the basement membrane of muscle fiber.

MATERIALS AND METHODS

Brain MR images in 15 patients (13 children, two adults) were reviewed and correlated with the patient's merosin status. Merosin was evaluated by means of immunocytochemical study of specimens from muscle biopsy.

RESULTS

Nine patients had merosin deficiency. All patients had diffuse white matter alterations similar to those seen in cases of leukodystrophy. Periventricular and subcortical white matter were involved. The corpus callosum and internal capsule were spared. Follow-up MR images were available in two patients; changes were nonprogressive. White matter signal intensity was normal in the six patients with normal uniform labeling against merosin. Ventricular dilatation and cortical atrophy were observed in both groups.

CONCLUSION

Diffuse white matter changes resembling those seen with leukodystrophy may be a valuable criterion for diagnosis of merosin deficiency in patients with classic congenital muscular dystrophy.

Genetics of laminin alpha 2 chain (or merosin) deficient congenital muscular dystrophy: from identification of mutations to prenatal diagnosis

Congenital muscular dystrophies (CMD) are a clinically and genetically heterogeneous group of muscle disorders, with autosomal recessive inheritance. Absence of the laminin alpha 2 chain in the skeletal muscle of patients with classical CMD has permitted the identification of a subgroup, referred to as 'merosin-deficient CMD or laminin alpha 2 chain deficient CMD'. We first identified a nonsense and a splice site mutation in laminin alpha 2 gene (LAMA2) (Glu1241 stop, 4573-2A-->T). We report here new mutations: nonsense mutations (Glu210stop, Trp2316stop) and 1- and 2-bp deletions (2418 delta C, 6968 delta TA), which result in truncation of the protein either in the short arm domains or in the C terminal globular domain and complete merosin deficiency. Another subgroup, referred to as 'partially-deficient in laminin alpha 2 chain' has been identified recently, and a LAMA2 missense mutation (Cys996Arg) has been shown to cause this partial deficiency. The laminin alpha 2 chain, together with the beta 1 or beta 2 and gamma 1 chains forms either laminin-2 (alpha 2-beta 1-gamma 1) or laminin-4 (alpha 2-beta 2-gamma 1). The LAMA2 mutations induce the formation of abnormal laminins which probably dramatically disturb the assembly and stability of the laminin network, one of the major components of the extracellular matrix in skeletal muscle. We report also the first prenatal diagnosis performed by direct mutation analysis.

Thoracoabdominal pattern of breathing in neuromuscular disorders

STUDY OBJECTIVE

To assess abnormalities in thoracoabdominal pattern of breathing (TAPB) in neuromuscular disorders during spontaneous breathing, intermittent positive pressure ventilation (IPPV) with and without abdominal (AB) binder, and immediately after IPPV.

DESIGN

Repeated measures design: Pre-IPPV spontaneous breathing, IPPV, IPPV with AB binder, and post-IPPV spontaneous breathing. In protocol 1, ventilator pressure was held constant at the individual value habitually adopted in sessions of IPPV. In protocol 2, it was increased stepwise from 5 to 30 cm H2O.

SETTING

University hospital, Department of Pediatrics, Intensive Care, and Neuro-Ventilatory Rehabilitation.

PATIENTS

Thirty-one patients with spinal muscular atrophy (SMA) and 19 patients with myopathy, mean age (+/- SD) 9.7 +/- 3 years.

MEASUREMENTS

Tidal volume (VT), percent thoracic contribution to VT (%RC), the phase angle between the thoracic and the AB volume changes and the labored breathing index, which is an index of asynchrony taking into account both the phase relationships and relative volumes of rib cage and AB compartments.

RESULTS

We observed marked abnormalities in TAPB during spontaneous breathing, especially in the SMA group. %RC, labored breathing index, and phase angle displayed nearly normal values during IPPV. IPPV pressures of 25 to 30 cm H2O were necessary to increase %RC above 80%. AB binding decreased VT, but led to larger thoracic volumes, especially in patients with SMA. Thoracic contribution to VT and thoracic volume after IPPV were higher than baseline levels.

CONCLUSIONS

The quantitative assessment of TAPB enhances the ability to estimate pulmonary function in neuromuscular disorders, and the efficiency of mechanical ventilation.

[Congenital muscular dystrophy with merosin deficiency: clinical, histopathological, immunocytochemical and genetic analysis]

A selective deficiency of a specific laminin isovariant, merosin made of M, B1 and B2 chains, was found in a series of 17 patients affected with congenital muscular dystrophy (CMD). The merosin deficiency was complete in 15 cases, and almost complete in two cases. An overexpression of the laminin A chain was seen in these biopsies, while B1 and B2 chains were normally expressed. Comparison of the clinical data with a series of 18 "merosin-non deficient" cases showed that the "merosin-deficient" cases were forming a more homogenous group than the "non-deficient" one. Hypotonia, contractures, motor development delay were generally more severe in the "merosin-deficient" series of cases. Moreover, white matter alterations were seen in most cases explored by MRI or scan imaging. A genetic linkage with a 6q2 locus, corresponding to the M chain gene localization, was found in a panel of informative families from French and Turkish origin with "merosin deficient" CMD. "Merosin non-deficient" families did not map on this locus. So, the "merosin-deficient" CMD can be considered as a peculiar entity within the group of Congenital Muscular Dystrophies.

Autopsies of sudden infant death syndrome--classification and epidemiology

An enquiry into sudden infant death syndrome (SIDS) in 1987 furnished us with detailed epidemiological data for 281 cases that underwent a thorough post-mortem examination. This analysis uses these data to evaluate the role the autopsy plays in explaining sudden death. The cases were classified into three diagnostic groups: explained causes of death (group 1), unexplained deaths with anomalies (group 2), and no anomaly (group 3). These 281 cases show the three essential features that characterize SIDS: over-representation of males, increased deaths during the second and third months of life, and increased deaths during winter. The autopsy examination revealed that many of these deaths had a medical explanation. Almost half were assigned to group 1. At the time of autopsy, no precise pathology could be diagnosed for 147 deaths; of these, 140 showed histological anomalies. There were only seven sudden deaths for which no abnormal sign was evident at the autopsy. These results are compared with those of similar studies and discussed in connection with three factors: the initial selection of cases, the nature and degree of the investigations, and the possible interpretations of the symptoms uncovered.

Readjusting the localization of merosin (laminin alpha 2-chain) deficient congenital muscular dystrophy locus on chromosome 6q2

The laminin alpha 2-chain gene mutations (LAMA2) are responsible for about 50% of the cases of classical congenital muscular dystrophy. These patients form a clinically homogenous group presenting merosin (laminin alpha 2-chain) deficiency in muscle biopsies. The LAMA2 gene has been previously localized on 6q22-23 and the disease locus mapped in a 16 cM interval in 6q2 by homozygosity mapping. In the present report we establish, by haplotyping additional microsatellites markers in 18 consanguineous families, that LAMA2 gene is more centromeric than previously thought: between the flanking markers, D6S407 and D6S1705, distant of 3 cM. In this interval the microsatellite D6S1620 is homozygous for all the patients. The localization of LAMA2 gene was confirmed by radiation hybrid mapping. The 3 new highly informative markers can be very useful for prenatal diagnosis.

Diaphragmatic paralysis in children: a review of 11 cases

We reviewed 11 pediatric cases of diaphragmatic paralysis related to nonspinal-cord injury which were managed in our Intensive Care Unit over the past 10 years. Three cases were secondary to birth trauma, 7 followed surgical procedures for congenital heart disease, and 1 occurred in association with injuries sustained in a motor vehicle accident. The paralysis was bilateral in 8 children. The diagnosis was initially suspected on clinical grounds because of respiratory distress, impossibility of weaning from the ventilator, and paradoxical abdominal respiratory movements. Confirmatory investigations included chest radiography, which revealed elevation of the affected hemidiaphragm, fluoroscopy and ultrasound, both of which demonstrated diminished diaphragmatic movement. Electromyography exhibited a failure of diaphragmatic response to phrenic nerve stimulation in 8 patients. All patients were mechanically ventilated; tracheostomy was required in 5 patients. Physiotherapy was considered a beneficial adjuvant measure. Diaphragmatic plication was attempted without success in 3 children. Seven children recovered without sequelae: Partial respiratory autonomy was achieved after an average of 2.6 months, complete autonomy after an average of 5.4 months. Two patients developed chronic lung disease; one of them remains unresponsive, and one child died following accidental extubation. We conclude that the diagnosis of diaphragmatic paralysis is predominantly clinical, and that the outcome of patients treated by adequate endotracheal mechanical ventilation is usually favorable.

Congenital muscular dystrophy with merosin deficiency

Congenital muscular dystrophy is one of the most frequent and severe childhood muscular dystrophies. Several forms of this disease have been described. The form associated with marked central nervous system disturbances, frequent in Japan, is known as Fukuyama congenital muscular dystrophy and was recently linked to chromosome 9. The most frequent form observed in occidental countries appears to be clinically characterized by exclusive involvement of skeletal muscle, and has been identified by clinico-pathological features which are often fallacious. A predominant histopathological feature is the marked increase in endomysial collagen tissue. We investigate whether laminin, a major component of the extracellular matrix, which is linked to the subsarcolemmal cytoskeleton by a large oligomeric complex of dystrophin-associated glycoproteins, could be involved in this form. We observed a specific absence of merosin, the laminin M chain, in 13 patients affected by classical non-Japanese form of congenital muscular dystrophy. This result allows the precise identification of a particular form of congenital muscular dystrophy and gives a clue to understanding its molecular pathogenesis.

Ondine's curse: a discussion of five cases

Five cases of central congenital hypoventilation, Ondine's curse, were studied. The diagnostic criteria were: lack of respiratory autonomy during sleep, abnormal CO2 test results and abnormal respiratory monitoring results during sleep. This hypoventilation induced chronic complications, such as a pulmonary arterial hypertension and psychomotor and/or growth retardation. The other conditions frequently associated with Ondine's curse were: brainstem disturbances, Hirschsprung disease and neuroblastoma. Since other brainstem dysfunctions are sometimes associated with hypoventilation and because complications can arise, these children routinely underwent complementary investigations. Treatment was symptomatic. Assisted mechanical ventilation was initiated as soon as possible and carefully monitored. The prognosis for these children has greatly improved and some of them lead a normal life with nightly assisted ventilation at home.

[Acute quinine poisoning treated with high dose of diazepam]

BACKGROUND

High concentrations of quinine, the drug of choice for severe malaria, are toxic to the cardiovascular system, producing hypotension and abnormal myocardial conduction.

CASE REPORT

An 8 year-old girl was admitted for fever, headache and arthralgias. Examination of a thick film of blood showed Plasmodium falciparum (parasitemia: 2%). She was given quinine intravenously. Ventricular tachycardia (150/min) and status epilepticus were seen 48 hours later, necessitating ventilatory support, plasma volume expander and IV sodium thiopental. On admission to an intensive care unit, the patient had hypothermia, was comatose (stage IV) with a reactive mydriasis and bradycardia (30/min). ECG confirmed bradycardia and showed a widened QRS complex. There was also a bilateral retinal edema. The blood level of quinine was 61 mumol/liter (therapeutic levels: 6-15). Retrospective inquiry revealed that the quinine initially administered had been incorrectly diluted. The child was treated with furosemide and adrenaline, followed by dobutamine and albumin infusion. She was then given diazepam (initial dose: 2 mg/kg then 6 mg/kg/day divided into 4 doses) intravenously, plus lidocaine, methylprednisolone and glycerol. The sinusal rhythm became normal 1 hour after the first bolus of diazepam. Consciousness gradually improved over the 10 days after admission while treatment was progressively discontinued. There were no sequelae, except for a transitory bilateral blindness.

CONCLUSION

The cardiovascular side-effects of quinine poisoning can be reversed with diazepam, as has previously been reported in cases of chloroquine poisoning.

[Respiratory form mof myasthenia gravis]

BACKGROUND

Extraocular, facial, bulbar and intercostal muscles are frequently affected in juvenile myasthenia gravis, especially during exacerbations. Acetylcholine receptor antibodies are often present in the blood in this type of myasthenic syndrome.

CASE REPORT

A girl presented with an exertional dyspnea at the age of 13 years, that improved after rest. All investigations were negative, except for lung function tests that showed a restrictive pattern. The diagnosis of juvenile myasthenia gravis was finally made at the age of 15 years because of the recurrence of sudden exertional dyspnea and a history of subtle weakness on repetitive movement leading to poor suckling, together with vocal and occasional swallowing difficulties. Dyspnea immediately improved after intravenous injection of 1 mg neostigmine, but the response was transient. No acetylcholine receptor antibody was found and a search for thymoma proved negative. Ambenonium chloride (Mytelase) was effective on clinical exacerbations, but the only improved test after 9 months of treatment was the functional residual capacity.

CONCLUSION

Anticholinesterase drugs must be tried in patients who present exertional dyspnea without bronchopulmonary or cardiac disease on the presumption of myasthenia gravis even when ocular or bulbar manifestations are absent.

[Whooping cough with Bordetella parapertussis isolation in an HIV positive child]

The authors report a case of whooping cough revealed by a pneumothorax in a 4 year-old boy with human immunodeficiency virus infection. Systemic signs of whooping cough were present. Bordetella parapertussis was isolated. Worsening of the HIV infection occurred simultaneously.

Gene for chronic proximal spinal muscular atrophies maps to chromosome 5q

Proximal spinal muscular atrophies represent the second most common fatal, autosomal recessive disorder after cystic fibrosis. The childhood form is classically subdivided into three groups: acute Werdnig-Hoffmann (type I), intermediate Werdnig-Hoffmann disease (type II) and Kugelberg-Welander disease (type III). These different clinical forms have previously been attributed to either genetic heterogeneity or variable expression of different mutations at the same locus. Research has been hindered because the underlying biochemical defect is unknown, and there are insufficient large pedigrees with the most common and severe form (type I) available for study. Therefore, we have undertaken a genetic linkage analysis of the chronic forms of the disease (types II and III) as an initial step towards the ultimate goal of characterizing the gene(s) responsible for all three types. We report here the assignment of the locus for the chronic forms to the long arm of chromosome 5 (5q12-q14), with the anonymous DNA marker D5S39, in 24 multiplex families of distinct ethnic origin. Furthermore, no evidence for genetic heterogeneity was found for types II and III in our study, suggesting that these two forms are allelic disorders.

[Oxygen therapy and assisted ventilation in children at home]

Home oxygen therapy is indicated in children with chronic obstructive lung disease when the oxygen content of arterial blood is decreased (oxygen partial pressure less than or equal to 50 mmHg). Three systems are available: compressed gas, bulk liquid, and oxygen concentrator. Oxygen may be administered via nasal cannulae, masks, hoods or endotracheal tubes 15 hours per day. FIO2 and SaO2 are periodically measured. Since 1972, when the experience of mechanical ventilation at home began with poliomyelitis teenagers, many children with neuromuscular diseases have been discharged from hospital with a ventilator. More recently, younger children with chronic lung diseases have also managed at home using intermittent positive pressure ventilation. Oral mechanical ventilation using pressure preset ventilators has been used in neuromuscular diseases; early and daily ventilation of children with paralytic respiratory muscles provides better development of the thoracic cage and of the lungs. Artificial ventilation can be performed by external means; we consider this type of ventilation as contraindicated as it causes thoracic deformities in young children.

[Diffusion of vancomycin in the cerebrospinal fluid, in the dog, in the absence of meningeal inflammation]

The diffusion of vancomycin into the cerebro-spinal fluid was studied in 5 healthy dogs. Its appears that vancomycin does diffuse across the blood-brain barrier. Though the concentrations reached in the CSF are low, they are of the same order of magnitude as the minimal inhibitory concentrations of this antibiotic towards the germs usually treated. The usual pharmacokinetic parameters were determined.

[Endocarditis of the ventricular septum. Echocardiographic diagnosis]

A 5 year-old child presented with prolonged fever, severe impairment of general condition and a pleuro-pericardium effusion. Echocardiography revealed a "bell-clapper-like tumor" in each ventricle, developed from the ventricular septum. Presence of a staphylococcal sepsis and early disappearance of the echocardiographic signs after antibiotic treatment allowed for diagnosis of bacterial endocarditis with abscess of the ventricular septum. Sinusitis and IgA deficiency were later found to be also present.

[Ventricular staphylococcal infections. Treatment with vancomycin by continuous venous infusion]

Thirteen cases of meningeal and/or ventricular infection and 1 case of septicaemia, all caused by staphylococci, were treated with continuous intravenous infusions of vancomycin. Repeated measurements of vancomycin plasma and CSF levels by microbiological assay or by high performance liquid chromatography showed that the antibiotic entered the CSF after 48 hours of treatment and that its concentrations in CSF remained stable at 1 to 4 micrograms/ml (mean: 2 micrograms/ml) throughout the 3 weeks' treatment period. After treatment was discontinued, vancomycin became undetectable in CSF within less than 24 hours. All the children were cured.