Targeted Re-Sequencing Emulsion PCR Panel for Myopathies: Results in 94 Cases

BACKGROUND

Molecular diagnostics in the genetic myopathies often requires testing of the largest and most complex transcript units in the human genome (DMD, TTN, NEB). Iteratively targeting single genes for sequencing has traditionally entailed high costs and long turnaround times. Exome sequencing has begun to supplant single targeted genes, but there are concerns regarding coverage and needed depth of the very large and complex genes that frequently cause myopathies.

OBJECTIVE

To evaluate efficiency of next-generation sequencing technologies to provide molecular diagnostics for patients with previously undiagnosed myopathies.

METHODS

We tested a targeted re-sequencing approach, using a 45 gene emulsion PCR myopathy panel, with subsequent sequencing on the Illumina platform in 94 undiagnosed patients. We compared the targeted re-sequencing approach to exome sequencing for 10 of these patients studied.

RESULTS

We detected likely pathogenic mutations in 33 out of 94 patients with a molecular diagnostic rate of approximately 35%. The remaining patients showed variants of unknown significance (35/94 patients) or no mutations detected in the 45 genes tested (26/94 patients). Mutation detection rates for targeted re-sequencing vs. whole exome were similar in both methods; however exome sequencing showed better distribution of reads and fewer exon dropouts.

CONCLUSIONS

Given that costs of highly parallel re-sequencing and whole exome sequencing are similar, and that exome sequencing now takes considerably less laboratory processing time than targeted re-sequencing, we recommend exome sequencing as the standard approach for molecular diagnostics of myopathies.

Infantile postural asymmetry and osteopathic treatment: a randomized therapeutic trial

The aim of this study was to assess the therapeutic efficacy of osteopathic treatment in infants with postural asymmetry. A randomized clinical trial of efficacy with blinded videoscoring was performed. Sixty-one infants with postural asymmetry aged 6 to 12 weeks (mean 9wks) were recruited. Thirty-two infants (18 males, 14 females) with a gestational age of at least 36 weeks were found to be eligible and randomly assigned to the intervention groups, 16 receiving osteopathic treatment and 16 sham therapy. After a treatment period of 4 weeks the outcome was measured using a standardized scale (4-24 points). With sham therapy, five infants improved (at least 3 points), eight infants were unchanged (within 3 points), and three infants deteriorated (not more than -3 points); the mean improvement was 1.2 points (SD 3.5). In the osteopathic group, 13 infants improved and three remained unchanged; the mean improvement was 5.9 points (SD 3.8). The difference was significant (p=0.001). We conclude that osteopathic treatment in the first months of life improves the degree of asymmetry in infants with postural asymmetry.

Cervical spinal cord atrophy in the atraumatically born neonate: one form of prenatal or perinatal ischaemic insult?

After atraumatic birth, three neonates presented with muscle hypotonia and weakness. Flaccid paresis of the upper extremities, spasticity of the lower extremities, dissociate sensory loss and autonomic dysfunction developed later. This ruled out the initial, tentative diagnoses of cerebral palsy, spinal muscular atrophy or hereditary neuropathy. Diagnostic imaging revealed marked thinning of the cervical spinal cord in all patients. The possible aetiology of these lesions is considered. In all cases, an antenatal or perinatal infarction is thought to be the most probable cause. Different clinical pictures following intrauterine spinal cord ischemia are discussed. Spinal cord lesion must be considered even after atraumatic birth.

Considerations to the policy of future clinical therapeutic trials in DMD

In spite of rapidly increasing insight into the molecular basis of neuromuscular diseases, treatment still relies on convention and clinical studies. Experience with a multicentre double blind treatment study in Duchenne muscular dystrophy and with consecutive steroid treatment documentation for up to 8 years enables us to identify a series of crucial points on which to focus while planning such clinical trials. The most important seem to be: a carefully structured, detailed study, clear-cut aims and objectives, expertise of investigators, sufficient training of examiners, and careful monitoring. If patients with neuromuscular diseases are treated outside structured studies, their course should be monitored comparably. Examples of the impact of such documentation are available from the ongoing German multicentre trial on the treatment of Duchenne muscular dystrophy.

Topiramate and metabolic acidosis in infants and toddlers

PURPOSE

Topiramate (TPM) inhibits carbonic anhydrase, with metabolic acidosis as a possible side effect, although this has been reported in only two adult cases. We investigated the acid-base metabolism in infants and toddlers treated with TPM.

METHODS

Nine infants and toddlers aged 5 months to 2.3 years (median, 6 months) were treated with TPM at maximal doses of 8.2-26 mg/kg/day (median, 11 mg/kg/day). The maximal TPM dose was achieved after 8-35 days (median, 17 days). TPM was given in addition to other antiepileptic drugs (AEDs) in five cases and as a sole AED in four patients with refractory epilepsy resistant to multiple AEDs. The diagnoses were infantile spasms (n = 5), epilepsia partialis continua (n = 1), infantile epileptic encephalopathy (n = 1), and Lennox-Gastaut syndrome (n = 2).

RESULTS

The blood gases were normal before treatment with TPM in all nine children. Metabolic acidosis developed in eight children after 8-26 days (median, 14 days) of TPM treatment with a minimum of serum bicarbonate between 15 to 18 mM (median, 17 mM), a minimal base excess between -6.2 and -11.2 mM (median, -7.9 mM), and pH between 7.22 and 7.40 (median, 7.35). Four of nine children showed clinical signs of hyperventilation and received oral sodium bicarbonate (1-2 mmol/kg), while TPM was still effective.

CONCLUSIONS

Because metabolic acidosis developed in eight of the nine infants and toddlers taking TPM, we would suggest that the acid-base metabolism be monitored in young children who receive TPM.

Acetazolamide treatment for infantile central sleep apnea

Central sleep apnea is a common respiratory pattern in healthy neonates. Nevertheless, frequent central sleep apnea associated with drops in oxygen saturation may contribute to infantile morbidity. Recently, low-dose acetazolamide was shown to reduce symptomatic central sleep apnea in adults. We treated 12 infants, median conceptional age 42 weeks (range, 40-44 weeks), with central sleep apnea. In all cases, the central apnea index was >40/h total sleeping time (apnea > or = 3 sec). The cumulative duration of drops in oxygen saturation below 90% was more than 3 min/h total sleeping time. All individuals received acetazolamide 7 mg/kg/day (orally, divided in three doses) for 11 weeks. Polysomnography was begun 10 hours before the first dose and continued for 10 hours after the third dose. Polysomnography was repeated after 6 weeks of treatment and 1 week after acetazolamide therapy was discontinued. Comparison of the respiratory patterns before and after treatment (10-hour recording after the third dose) showed a decrease in the median central apnea index from 74/h (range, 42-152/h) to 13/h (range, 6-49/h). The median of the cumulative duration of drops in oxygen saturation below 90% decreased from 3.6 min/h (range, 3.1-9.2 min/h) to 0.07 min/h (range, 0-0.5 min/h). Basal oxygen saturation increased from 95 (92-97%) to 98% (96-99%). This improvement was maintained in the final polysomnography (12 weeks after therapy was begun and 1 week after completion of the 11-week course). No adverse effects were noted. We conclude that low-dose acetazolamide treatment may be useful for the treatment of central infantile sleep apnea associated with hypoxemia.

Severe congenital myasthenic syndrome due to homozygosity of the 1293insG epsilon-acetylcholine receptor subunit mutation

Recently, a congenital myasthenic syndrome (CMS) with end-plate acetylcholine receptor (AChR) deficiency due to missense mutations in the genes for the AChR subunit was described. The first observed patient with this CMS was heteroallelic for the two epsilon-AChR subunit mutations epsilon1101insT and epsilon1293insG. This patient had only a moderate phenotype with mild muscle weakness and abnormal fatigue. We have now found homozygosity for the epsilon1293insG mutation in a severely affected CMS patient, who lost the ability to walk in midchildhood and shows profound weakness and muscle wasting. Our observation allows a genotype-phenotype correlation illustrating how differences in the AChR mutation haplotype can profoundly influence disease severity.

Ischemic stroke and migraine in childhood: coincidence or causal relation?

Although migraine is an accepted cause of cerebral infarction in adults, this association is less well recognized in children. We present two children with migraine and cerebral infarction, which we regard as migrainous stroke, though neither patient fulfills all criteria of the International Headache Society for the diagnosis of migrainous infarction. Review of the literature concerning examples of migraine-associated stroke in childhood suggests that these criteria are too restrictive to comprise the majority of migrainous strokes, especially in this age group.

Hamartoma of the triceps surae muscle

A 9-year-old, otherwise healthy girl presented with a 5-year history of pain in her right calf with retarded growth and development of an equinus contracture of her right leg. Magnetic resonance imaging showed an irregular mass with heterogeneous enhancement after contrast in her right triceps surae muscles, especially the soleus. Histological studies of this triceps surae muscle tissue revealed a haphazard distribution of adipose and connective tissue, striated and smooth muscle cells, vessels and lymphoid follicles, as well as nerve bundles which, together, were considered components of a hamartoma.

[Cataplexy in type C Niemann-Pick disease]

Cataplexy usually occurs as a part of the tetrad of clinical phenomena of idiopathic narcolepsy. Symptomatic cases are rare. A 4 years old girl from consangineous parents had recurrent loss of muscle tone and fell to the ground, when she laughed. The EEG was normal. Prolonged neonatal jaundice with cholestasis, hepatosplenomegaly, mental regression, supranuclear ophthalmoplegia, and foam cells led to the diagnosis of Niemann-Pick disease type C with symptomatic cataplexy. Symptomatic forms of the narcolepsy-cataplexy complex should be considered, when there is an early onset before puberty, cataplectic attacks predominate the narcoleptic attacks, and when additional neurological symptoms occur. Symptomatic cataplexy occurs in Niemann-Pick disease type C. It is considered to be the result of lesions of the pontine reticular formation.

Glycosyl-phosphatidylinositols of Trypanosoma congolense: two common precursors but a new protein-anchor

The parasitic protozoan Trypanosoma congolense exhibits a dense surface coat which is pivotal for immunoevasion of the parasite. This dense surface coat is made of a single protein species, the variant surface glycoprotein, which is present in a high copy number. The protein is anchored to the plasma membrane by a glycosyl-phosphatidylinositol membrane anchor. A detailed study of the structure of T. congolense strain 423 (clone BENat 1.3) variant surface glycoprotein glycosyl-phosphatidylinositol membrane anchor was performed. Radioactively labelled core-glycan prepared by dephosphorylation, deamination and reduction was analysed by high-pH anion-exchange chromatography, size-exclusion and lectin affinity chromatography. Additionally the glycosyl-phosphatidylinositol membrane anchor core-glycan was purified from a bulk preparation of variant surface glycoprotein and subjected to mass spectrometry and methylation analysis. Using these methods we could identify a novel galactose-beta 1,6-N-acetyl-glucosamine-beta 1,4-branch modifying the mannose adjacent to the glucosamine of the mannose-alpha 1,2-mannose-alpha 1,6-mannose-alpha 1,4-glucosamine core-glycan of the variant surface glycoprotein glycosyl-phosphatidylinositol membrane anchor. Furthermore the biosynthetic pathway leading to this novel structure was investigated. Two putative glycosyl-phosphatidylinositol anchor precursors were identified having structures identical to the previously characterized Trypanosoma brucei brucei glycolipids P2 and P3 (also designated glycolipid A and C) consistent with a trimannosyl core and a dimyristoyl-glycerol. Both glycosyl-phosphatidylinositol anchor precursors of T. congolense do not possess the side-branch modification found on the mature protein membrane anchor, implying that the sugar side-chain is added to the anchor during its passage through the Golgi-apparatus.

Dystrophinopathies

The discovery of the subsarcolemmal muscle fiber protein dystrophin has, to a certain extent, replaced former nosological terms of Duchenne (DMD) and Becker (BMD) muscular dystrophies by the term dystrophinopathies. The immunohistochemical and Western blot analysis of dystrophin has not only enlarged the clinical spectrum of dystrophinopathies, but has also made carrier detection of DMD more reliable, particularly in manifesting carriers without family history. Moreover, prenatal muscle biopsy, under selected circumstances, can show presence or absence of dystrophin, ie, in the latter case an affected male fetus. Molecular genetics have provided a wealth of genetic details in the dystrophinopathies, but therapy has not yet succeeded to a similar extent, on the contrary, myoblast transplantation has not resulted in any clinical improvement.

Prenatal diagnosis of infantile neuronal ceroid-lipofuscinosis: a combined electron microscopic and molecular genetic approach

Based on two unrelated index patients afflicted with INCL, fetal chorion tissues were studied from subsequent pregnancies of the two respective mothers resulting in the prenatal diagnosis of INCL in two of the three pregnancies. Documentation of INCL was based on electron microscopy and DNA studies of the biopsied chorion tissue, later confirmed in the two affected fetuses after termination of their pregnancies by demonstrating INCL-specific lipopigments in post-mortem tissues, in the liver of both aborted fetuses and, additionally, in spleen and skeletal muscle of one of the affected fetuses. The autolysis of the aborted tissues, however, precluded a systematic documentation of all affected cell types and tissues. Thus, prenatal diagnosis of INCL is feasible and reliable for both Finnish and non-Finnish families.

Deflazacort vs. prednisone in Duchenne muscular dystrophy: trends of an ongoing study

Several studies have demonstrated the slowing effect of corticosteroids on the decline of muscle strength in Duchenne muscular dystrophy (DMD). Deflazacort (DFC) is supposed to have fewer side effects than prednisone (PRED). An ongoing double blind multicenter study is comparing the effects and side effects of deflazacort (0.9 mg/kg/day) and prednisone (0.75 mg/kg/day) in DMD. This interim report includes data for 67 boys between age 5 years and loss of ambulation. Besides the common clinical and laboratory data for chronic corticoid treatment, motor performance has been tested. Interim results, 3-15 months after starting the medication, show some scattering but no grouping of data for all the functions tested: timed motor functions, sum of the strength of 20 muscles according to a 10-point scale on manual testing, weight gain, osteocalcin and alkaline phosphatase. Only the changes in CK activity after 3 months medication might reflect two equal groups without any correlation with the initial activity or with other parameters. On average, there was no clear-cut loss of muscle strength or performance. Except for in 4 patients, who were excluded due to unacceptable weight gain and/or loss of ambulation, there were no side effects considered to be serious. The results suggest that (i) DFC and PRED in equal anti-inflammatory dosage are similarly or equally efficient in slowing down the decline of muscle strength in DMD; (ii) benefits outweigh the side effects. This allows the study to continue as designed.

[Multi-segmental fusion of scoliosis in Duchenne's muscular dystrophy]

Operations in scoliosis in patients suffering from an advanced stage of Duchenne muscular dystrophy are associated with a higher risk due to the extent of the curves, the respiratory insufficiency and frequent cardiomyopathia. Progressive scolioses in 20 wheelchair patients with an age between 10.5-18.3 years (mean 14.6 years) were treated by CDI. The mean preoperative angle in this group was 70.6 degrees, the postoperative angle 31.2 degrees (mean correction 39.4 degrees or 55.8%). The preoperative lordosis of the lumbar spine (mean angle 4.1 degrees) was corrected to 17.8 degrees postoperatively. The average intraoperative blood loss (2300 ccm) was evident more compared with idiopathic scoliosis. One neurologic complication (postoperative disturbance of bladder function) was observed. Nowadays early surgical correction and stabilization (Cobb angle > 20 degrees) has to be recommended as the treatment of choice for scolioses in Duchenne muscular dystrophy using multisegmental instrumentation methods to enable rapid mobilisation and a postoperative care without brace or cast. This conception allows a prophylactic operation including the following targets: prolongation of life expectancy, improvement of sitting position and prevention of rapid deterioration of lung function including assisted mechanical ventilation in late stages.

Tethered cord after spina bifida aperta: a longitudinal study of somatosensory evoked potentials

Progressive neurological deterioration may occur after meningomyelocele repair. Magnetic resonance imaging almost invariably demonstrates a conus medullaris in an abnormally low position, whether neurological symptoms develop or not. Surgery of a secondary tethered cord is indicated when progression of neurological symptoms is documented. We performed a longitudinal study of posterior tibial nerve somatosensory evoked potentials (SSEPs) in children and adolescents after neonatal meningomyelocele repair. All patients were able to walk. Declining or negative posterior tibial nerve SSEPs were recorded in 15 patients; 14 of these had clinical signs of a secondary tethered cord. After surgery of the tethered cord, the SSEPs improved in 8 of 10 patients. Posterior tibial nerve SSEPs may contribute to the diagnosis of secondary tethered cord. After untethering, the evoked potentials demonstrate recovery of spinal cord function and might help to delineate prognosis.

Aplasia of the retinal vessels combined with optic nerve hypoplasia, neonatal epileptic seizures, and lactic acidosis due to mitochondrial complex I deficiency

A newborn male with mitochondrial complex I deficiency suffered from neonatal epileptic seizures, which later developed into infantile spasms. The infant was blind due to aplasia of the retinal vessels and hypoplasia of the optic nerve. There was congenital lactic acidosis, which persisted in later life. The boy was microcephalic and retarded. Muscular hypotonia later shifted to spasticity. Succinic acid was increased in urine. We assume that the aplasia of the retinal vessels is due to damage of the retinal ganglion cells caused by the mitochondrial disease in the first 3 to 4 months of pregnancy.

[The automated determination of the dibucaine number using the Greiner G450 selective analyzer. A routine parameter of significance?]

Patients who are homozygous for an atypical pseudocholinesterase enzyme (PCHE) suffer a prolonged neuromuscular block after succinylcholine application. In order to determine which patients have atypical PCHE preoperatively, an automated method using the Greiner G450 analyzer was developed.

PATIENTS AND METHODS

The contribution of blocked and unblocked PCHE by dibucaine hydrochloride (optimal concentration 10(-4) mol/l;) was determined in 113 patients (ASA groups 1-2) and the dibucaine number (DN) was evaluated.

RESULTS

According to the DN, the patients were subdivided into three groups: group A (PCHE 5.01 +/- 1.64 kU/l, DN 74.47 +/- 0.87); group B (PCHE 4.28 +/- 3.41 kU/l, DN 64.95 +/- 3.41); group C (PCHE 1.33 +/- 0.54 kU/l, DN 13.08 +/- 2.19;). PCHE and DN of group A corresponded with normal standard values, whereas the patients in groups B and C could be considered to be patients with heterozygous and homozygous atypical PCHE, respectively.

CONCLUSIONS

Our data indicate that an automated analysis of blocked and unblocked PCHE with the Greiner G450 can be easily done in a routine laboratory. By interpreting the DN, the possible risks of delayed succinylcholine degradation can probably be prevented.

[Progressive Duchenne muscular dystrophy: general practice aspects of diagnostic assessment]

The analysis of 57 cases of Duchenne muscular dystrophy (DMD) from W.-Germany outlined an average delay in motor development with an extended period of time between learning to stand and to walk. 33 patients could not walk when they were 16 months old. At the age of 27 months people without medical training generally noticed first symptoms. Unexpectedly often quantitative deficiencies in movements became evident. On average 26 months passed until DMD was diagnosed. To improve the situation, the authors propose a selective screening of boys who are not able to walk without help when they are 16 months old (90th percentile for healthy children).

Identification of infants at risk for infantile spasms by neonatal polygraphy

Reevaluation of neonatal EEGs and polygraphic tracings of 40 infants with infantile spasms and/or hypsarrhythmia resulted in the constitution of a compound score for the identification of infants at risk for infantile spasms by neonatal EEG. The score comprises 8 distinct items: 2 concern behavioral characteristics, 6 abnormality of EEG background activity and paroxysmal events. A tracing registered at conceptional age 36 to 44 weeks (eventually up to 50 weeks) presenting at least 4 of these 8 items is scored positive for the risk of evolving hypsarrhythmia. In a prospective study the polygraphic tracings of 941 newborn infants were evaluated for risk: 18 infants suffering from perinatal distress and 7 newborns with malformations of the brain were scored positive and all 25 developed infantile spasms and/or hypsarrhythmia. One infant with later infantile spasms was missed by the scoring system. None of the remaining infants scored negative manifested infantile spasms. Thus, correct positive prognostication was 100% and false negative 0.1%. By conventional EEG 5 out of 8 patients with infantile spasms were correctly predicted. The high validity of the risk-score based on polygraphic tracing between conceptional age 36 to 44 weeks may allow pre-onset treatment preventing secondary mental deterioration due to hypsarrhythmia and infantile spasms.

Muscle adenylate kinase in Duchenne muscular dystrophy

On the basis of electrophoretic and enzyme inhibition studies it was postulated that an aberrant adenylate kinase occurs in muscle and serum of patients with Duchenne muscular dystrophy (Schirmer, R.H. and Thuma, E. (1972) Biochim. Biophys. Acta 268, 92-97; Hamada, M. et al. (1981) Biochim. Biophys. Acta 660, 227-237; Hamada et al. (1985) J. Biol. Chem. 260, 11595-11602). On the basis of the following results we conclude that Duchenne muscular dystrophy patients do not possess an unusual adenylate kinase isoenzyme. In muscle biopsies from five Duchenne patients, the electrophoretic mobility of adenylate kinase and the inhibition of the enzyme by P1, P5-di(adenosine-5')pentaphosphate (Ap5A) was normal. Because of the high SH-group content of the extracts from Duchenne muscle, high concentrations of Ellman's reagent were needed to inhibit adenylate kinase activity in these samples. In Duchenne plasma the adenylate kinase activity was elevated. Like in muscle specimens, the DTNB inhibition curves were shifted to higher reagent concentrations; this was due to a high SH-group content of Duchenne plasma when compared with normal plasma. With respect to inhibition by Ap5A and electrophoretic mobility, Duchenne adenylate kinase in Duchenne plasma behaved like normal muscle adenylate kinase in normal plasma. It was noted that normal muscle adenylate kinase changes its electrophoretic behaviour when mixed with normal or Duchenne plasma. This finding had been considered previously as evidence for the presence of an aberrant adenylate kinase in Duchenne plasma.

Idiopathic de Toni-Debré-Fanconi syndrome with absence of proximal tubular brush border

In a girl with idiopathic de Toni-Debré-Fanconi syndrome associated with psychomotor retardation, severe renal tubular dysfunction was observed from the first day of life. At the age of 21/2 and 4 years the glomerular filtration rate (GFR) was only 60 ml/min/1.73 m2. No tubular transport of glucose, phosphate, paraaminohippurate and amino acids could be demonstrated. The tubular handling of uric acid, potassium and calcium, was also disturbed. Renal net acid excretion was zero at a plasma bicarbonate level of 14 mmol/l. Urinary osmolality ranged between 88 and 680 mosmol/kg. During hypotonic saline diuresis GFR decreased further; a GFR of 19 ml/min/1.73 m2 was accompanied by a fractional distal sodium delivery of 96.5% and a fractional free water clearance of 73%. In a renal biopsy specimen the proximal tubular cells showed variations in height with dedifferentiation and a widespread absence of brush border on electron microscopy. This formerly undescribed tubulopathy offers a unique chance to investigate glomerulo-tubular balance, adaptive mechanisms of distal tubular transport and renal metabolism under conditions where an apparently unchanged ultrafiltrate is offered by the proximal tubule to the loop of Henle and to a primarily intact distal tubule.

Capping of lymphocytes for carrier detection in Duchenne muscular dystrophy: technical problems and a review of the literature

There has been considerable interest in capping of lymphocytes in patients with Duchenne muscular dystrophy (DMD). However, the results from different authors are controversial. We have investigated cap formation in thirteen families with DMD, using a method standardized in our laboratory, and could establish diminished capping in all 12 patients and in 12 of the 13 mothers. By examining cap formation simultaneously with whole polyvalent antiserum, with F(ab)2 fragment of polyvalent antiserum, and with monospecific antisera we could also confirm this observation of defective capping in 7 patients and 4 carriers, as compared to 9 control subjects likewise examined. We have indications that treatment of the lymphocytes under unfavourable conditions e.g. preincubation in buffer solution might accentuate the decrease of lymphocyte capping in patients and carriers.

Chlorambucil neurotoxicity: report of two cases

Chlorambucil neurotoxicity was observed in two children treated for frequently relapsing minimal change nephrotic syndrome. In the first child the drug was overdosed. Myoclonic jerks were observed, followed by a generalized tonic-clonic seizure. Concomitant EEG abnormalities disappeared after discontinuation of therapy, but reappeared 6 months later without further seizures. In the second child chlorambucil treatment was started twice, but had to be interrupted each time; the first time because of sudden collapse, bradycardia and respiratory arrest, and the second time because of myoclonic jerks. EEG changes were limited to generalized slowing and improved after discontinuation of therapy. According to the literature chlorambucil neurotoxicity is found almost exclusively in children, after overdosage or in the nephrotic syndrome. Strict neurologic supervision of patients treated with this drug is recommended.

Capping of lymphocytes in patients and carriers of Duchenne muscular dystrophy

Recent results showed that Duchenne muscular dystrophy is probably associated with a generalized membrane defect. The capping phenomenon in lymphocytes indicates normal intramembrane protein mobility and disturbances of this phenomenon are is believed to reflect membrane alterations. We have investigated capping in lymphocytes from 19 patients with Duchenne muscular dystrophy, 13 carriers, 8 patients' sisters, 14 patients' aunts and 52 normal controls. All 19 patients showed a reduction in capping both with fluorescein conjugated polyvalent goat antiserum (mean +/- SD = 18.5 +/- 5.1% and with fluorescein labeled Concanavalin A (mean +/- SD = 10.8 +/- 3.1%) as compared to controls. Normal persons (n = 52) have a mean of 50.2 +/- 9.9% (SD) capping with polyvalent anti-immunoglobulin (range: 32--72.5%) and 25.6 +/- 3.6% with F-Con A (range: 18.5--31.5%). 12 of the 13 mothers, as well as 5 of the 8 patients' sisters, also exhibited decreased lymphocyte capping to the same extent as the patients. Creatine kinase activity (CK) was elevated only in 4 mothers and 2 of the sisters. Our results indicate that this method might be of value in detecting carriers and can yield less false negative results as the CK-activity test.

Neonatal respiratory insufficiency due to centronuclear myopathy

Two neonates showing generalized hypotonia, weakness of limbs, trunk, and oral musculature died because of muscular respiratory distress. The diagnosis of centronuclear (or myotubular) myopathy was established by histological and histochemical techniques. The genetic situation and routine laboratory data including electromyography were compared with similar cases in the literature; findings were inconclusive with respect to this diagnosis. These results indicate the need for a muscle biopsy and the use of histochemical stainings and/or electronmicroscopical investigation for a proper diagnosis in hypotonic newborns under respiratory distress after exclusion of etiologies other than neuromuscular diseases. Still the diagnosis of centronuclear myopathy in a neonate does not allow a precise prognosis. Increased awareness of this disorder and adequate diagnostic workup is needed in order to extend our understanding and to clarify the prognosis.

[Familial paroxysmal choreoathetosis. Clinical course, L-dopa-effect (author's transl)]

The clinical course of two boys with familial paroxysmal choreoathetosis was traced. As far as the medical history could be retrieved, their family has been affected by this disease for three generations. Except for this disorder, the patients' development and psychophysical state are unremarkable. Both boys responded well but at times incompletely to anticonvulsants. Therefore L-Dopa was introduced to the therapeutic regime of the younger, more severely affected boy. L-Dopa caused an appreciable decline of the frequency of the paroxysms.