Somatropin treatment of spinal muscular atrophy: a placebo-controlled, double-blind crossover pilot study

In preclinical studies growth hormone and its primary mediator IGF-1 have shown potential to increase muscle mass and strength. A single patient with spinal muscular atrophy reported benefit after compassionate use of growth hormone. Therefore we evaluated the efficacy and safety of growth hormone treatment for spinal muscular atrophy in a multicenter, randomised, double-blind, placebo-controlled, crossover pilot trial. Patients (n = 19) with type II/III spinal muscular atrophy were randomised to receive either somatropin (0.03 mg/kg/day) or placebo subcutaneously for 3 months, followed by a 2-month wash-out phase before 3 months of treatment with the contrary remedy. Changes in upper limb muscle strength (megascore for elbow flexion and hand-grip in Newton) were assessed by hand-held myometry as the primary measure of outcome. Secondary outcome measures included lower limb muscle strength, motor function using the Hammersmith Functional Motor Scale and other functional tests for motor function and pulmonary function. Somatropin treatment did not significantly affect upper limb muscle strength (point estimate mean: 0.08 N, 95% confidence interval (CI:-3.79;3.95, p = 0.965), lower limb muscle strength (point estimate mean: 2.23 N, CI:-2.19;6.63, p = 0.302) or muscle and pulmonary function. Side effects occurring during somatropin treatment corresponded with well-known side effects of growth hormone substitution in patients with growth hormone deficiency. In this pilot study, growth hormone treatment did not improve muscle strength or function in patients with spinal muscular atrophy type II/III.

Aromatic L-amino acid decarboxylase deficiency: clinical features, drug therapy and follow-up

BACKGROUND

Aromatic L-amino acid decarboxylase (AADC) deficiency is a disorder of biogenic amine metabolism resulting in generalized combined deficiency of serotonin, dopamine and catecholamines. Main clinical features are developmental delay, muscular hypotonia, dystonia, oculogyric crises and additional extraneurological symptoms. Response to therapy has been variable and unsatisfactory; the overall prognosis is guarded.

METHODS

To gain more insight into this rare disorder we collected clinical and laboratory data of nine German patients. All patients were clinically examined by one investigator, and their responses to different drug regimes were evaluated by the patients' charts.

RESULTS

Symptoms were obvious from early infancy. Later, main neurological features were truncal muscular hypotonia, hypokinesia, oculogyric crises and rigor. Three patients had single seizures. All patients presented distinct extraneurological symptoms, such as hypersalivation, hyperhidrosis, nasal congestion, sleep disturbances and hypoglycaemia. In CSF all patients revealed the pattern typical of AADC with decreased concentrations of homovanillic and 5-hydroxyindoleacetic acid and elevated concentration of 3-ortho-methyldopa. Diagnosis was confirmed by measurement of AADC activity in plasma in all patients. Drug regimes consisted of vitamin B6, dopamine agonists, MAO inhibitors and anticholinergics in different combinations. No patient achieved a complete recovery from neurological symptoms, but partial improvement of mobility and mood could be achieved in some.

CONCLUSION

AADC deficiency is a severe neurometabolic disorder, characterized by muscular hypotonia, dystonia, oculogyric crises and additional extraneurological symptoms. Medical treatment is challenging, but a systematic trial of the different drugs is worthwhile.

Distinct inflammatory properties of late-activated macrophages in inflammatory myopathies

Distinct mechanisms such as humeral immunity in dermatomyositis (DM) and T-cell-mediated cytotoxicity in polymyositis (PM) contribute to the pathology of inflammatory myopathies. In addition, different subsets of macrophages are present in both diseases. Herein, the characteristics of 25F9-positive macrophages in skeletal muscle inflammation are outlined. Muscle biopsies of subjects with DM and PM were studied by immunohistochemical multi-labelling using the late-activation marker 25F9, together with markers characterizing macrophage function including IFN-gamma, iNOS, and TGF-beta. In PM, a robust expression of IFN-gamma, iNOS, and TGF-beta was observed in inflammatory cells. Double- and serial-labelling revealed that a subset of 25F9-positive macrophages in the vicinity of injured muscle fibres expressed iNOS and TGF-beta, but not IFN-gamma. In DM, IFN-gamma, iNOS and TGF-beta were also expressed in inflammatory cells in the endomysium. Double- and serial-labelling studies in DM indicated that 25F9-positive macrophages expressed TGF-beta and to a lesser degree iNOS, but not IFN-gamma. In conclusion, our data suggest that late-activated macrophages contribute to the pathology of inflammatory myopathies.

GAMT deficiency: Features, treatment, and outcome in an inborn error of creatine synthesis

BACKGROUND

Guanidinoactetate methyltransferase (GAMT) deficiency is an autosomal recessive disorder of creatine synthesis. The authors analyzed clinical, biochemical, and molecular findings in 27 patients.

METHODS

The authors collected data from questionnaires and literature reports. A score including degree of intellectual disability, epileptic seizures, and movement disorder was developed and used to classify clinical phenotype as severe, moderate, or mild. Score and biochemical data were assessed before and during treatment with oral creatine substitution alone or with additional dietary arginine restriction and ornithine supplementation.

RESULTS

Intellectual disability, epileptic seizures, guanidinoacetate accumulation in body fluids, and deficiency of brain creatine were common in all 27 patients. Twelve patients had severe, 12 patients had moderate, and three patients had mild clinical phenotype. Twenty-one of 27 (78%) patients had severe intellectual disability (estimated IQ 20 to 34). There was no obvious correlation between severity of the clinical phenotype, guanidinoacetate accumulation in body fluids, and GAMT mutations. Treatment resulted in almost normalized cerebral creatine levels, reduced guanidinoacetate accumulation, and in improvement of epilepsy and movement disorder, whereas the degree of intellectual disability remained unchanged.

CONCLUSION

Guanidinoactetate methyltransferase deficiency should be considered in patients with unexplained intellectual disability, and urinary guanidinoacetate should be determined as an initial diagnostic approach.

[Pitfalls in the diagnosis of congenital hyperinsulinism: a case report and review of the literature]

BACKGROUND

Congenital hyperinsulinism is the most common cause for recurrent hypoglycaemia in neonates and infants. Uncontrolled hypoglycaemia leads to seizures and long-term cerebral damage. Often, the diagnosis is delayed because of nonspecific symptoms and confusing laboratory results.

PATIENT

We report a patient with hyperinsulinism who was initially wrongly diagnosed as having idiopathic cerebral convulsions and treated accordingly.

CONCLUSIONS

Diagnosis of congenital hyperinsulinism is based on a strong suspicion and a thorough family history. Normal random blood glucose or random insulin levels are not helpful in excluding this disease.

Beta-sarcoglycan gene mutations in Turkey

The term limb-girdle muscular dystrophy (LGMD) refers to a group of muscular dystrophies that, at the outset, affect primarily the muscles of the hip and shoulder girdle. Limb-girdle muscular dystrophy is genetically heterogeneous comprising autosomal dominant (types LGMD 1A-1E) as well as autosomal recessive forms (types LGMD 2A-2J known). A subgroup among the autosomal recessive forms comprises the sarcoglycanopathies (LGMD2C-2F), caused by mutations in the gamma (gamma-SG), alpha (alpha-SG), beta (beta-SG) and delta (delta-SG) sarcoglycan genes, respectively. The sarcoglycans form the sarcoglycan complex, part of the dystrophin-associated glycoproteins. Mutations in the beta-SG gene causes LGMD2E. Disease severity, in this form, varies from mild to severe phenotypes depending on the individual mutation. Homozygous missense mutations in critical locations may result in the total absence of alpha-, beta- and gamma-sarcoglycan from the muscle membrane and a phenotype as severe as null mutations. In the present study, through screening 80 unrelated LGMD2 families, we identified 13 families with LGMD2E. Mutations in the beta-SG gene were identified in 12 patients from nine families. One of these patients carried a previously reported truncating mutation (Q11X), while the other 11 carried novel missense/rameshift mutations (M1L, V89M, I92T, I92S, 739insA), some of which were seen in more than one patient and may, therefore, be more common in the Turkish population.

Stroke-like pattern in DTI and MRS of childhood mitochondrial leukoencephalopathy

In a 13-month-old boy with recurrent motor deterioration provoked by fever MRI and proton MRS detected a leukoencephalopathy with reduced cerebral metabolites and elevated lactate. At follow-up 6 and 16 months later these abnormalities improved gradually. Serial diffusion tensor imaging revealed a stroke-like pattern with an initial strong reduction of the apparent diffusion coefficient followed by elevated values 6 months later. The relative diffusion anisotropy remained reduced. Muscle biopsy confirmed a mitochondrial encephalomyopathy.

[Pigmented retinopathy as a presenting sign of mitochondrial encephalomyopathy without external ophthalmoplegia]

BACKGROUND

Mitochondrial encephalomyopathies result from deletions in the nuclear or mitochondrial (mt) DNA. Deletions in the mtDNA are often sporadic. Mitochondriopathies are commonly associated with chronic progessive external ophthalmoplegia (CPEO). Here we describe a patient with a structural mtDNA aberration whose presenting sign was impaired visual acuity in the presence of a pigmented retinopathy but lack of impaired ocular motility.

PATIENT

A 7-year-old girl presented with impaired visual acuity (0.4 OD and 0.5 OS), coarse hyperpigmentation of the posterior pole and diffuse hyperpigmentation with irregular depigmentation in the periphery. Scotopic and photopic as well as multifocal ERG were abnormal. Further symptoms included an incomplete inner ear deafness, ataxia, lapses of coordination and an intention tremor. Compared with her twin sister, the patient's speech was less modulated and slower. MRI scanning disclosed symmetric changes of density in the basal ganglia and nucleus dentatus as well as in the brainstem. ECG yielded no evidence of an AV-node block. Molecular biological analysis showed a structural rearrangement of the mtDNA.

CONCLUSIONS

Mitochondrial encephalomyopathies in early ages may present with pronounced retinal changes in the absence of external ophthalmoplegia.Therefore, it appears prudent to include a neuropediatric evaluation as well as a mutation screening of the mtDNA in the evaluation of pediatric patients with diffuse non-specific pigmented retinopathies.

Cytochrome c oxidase partial deficiency-associated Leigh disease presenting as an extrapyramidal syndrome

Leigh disease is a subacute neurodegenerative disorder characterized by symmetric necrotic lesions in the basal ganglia, cerebellum, thalamus, brain stem, and optical nerves and caused by altered oxidative phosphorylation. We describe the clinical, biochemical, neuroimaging, and molecular studies of a 19-year-old boy with early-onset Leigh disease manifesting as severe extrapyramidal disorder with generalized dystonia and choreoathetosis. He was born of healthy parents after an uneventful pregnancy and delivery. At the age of 2 1/2 years, after a minor respiratory infection, he developed unstable, broad-based gait and tremor of the hands. These symptoms persisted for the next several years, when ataxia became more prominent. Difficulty in swallowing, dysarthria, trunk dystonia, and marked dyskinesia of the arms and hands gradually developed. Nystagmus, transient ptosis, and strabismus also appeared. Abnormal laboratory findings included elevated plasma and cerebrospinal fluid lactate and pyruvate, with an abnormal lactate/pyruvate ratio. Cranial computed tomography and magnetic resonance imaging demonstrated signs of cerebellar atrophy, bilateral and symmetric hypodensities in the lentiform nucleus and thalamus, and transient hyperintensities of cerebral peduncles in T2-weighted sequences suggestive of Leigh disease. Muscle biopsy revealed isolated fiber atrophy, necrotic fibers undergoing phagocytosis, and no ragged-red fibers. The measured catalytic activity of cytochrome c oxidase in skeletal muscle homogenates demonstrated a partial cytochrome c oxidase deficiency No abnormalities in the mitochondrial genome and in the SURF-1 gene were found. The boy is currently receiving levodopa therapy, creatine monohydrate, and a high dosage of thiamine and lipoic acid, his condition is stabilized, and extrapyramidal symptoms are less pronounced.

Progressive sensorineural hearing loss in children with mitochondrial encephalomyopathies

OBJECTIVE

Mitochondrial disorders are responsible for a variety of neurological syndromes. Specific mitochondrial DNA mutations have been identified recently in some of these rare disorders. Clinical symptoms may occur in different organs to various extent; often they are associated with progressive hearing loss. The aims of this study were to determine incidence, onset, and characteristics of hearing loss in children with mitochondrial encephalomyopathies and to investigate a possible correlation between the degree of hearing loss and neurological symptoms. In addition, we investigated the prognostic value of hearing loss as a predictor of the disease.

STUDY DESIGN

From August 1992 to September 1998, 29 patients ranging in age from 5 to 23 years (mean years) were studied. These children were hospitalized for diagnostic purposes in the neuropediatric department.

METHODS

The mitochondrial disorder was diagnosed by clinical and laboratory testings, including analysis of the mtDNA. Audiological evaluation consisted of measurements of pure-tone and speech audiometry, tympanometry, and acoustic refle- threshold testing, auditory brainstem response, and evoked as well as distortion-product otoacoustic emissions.

RESULTS

A sensorineural hearing loss was identified in 12 children. Three of these were diagnosed as having classic Kearns-Sayre syndrome; five as having multisystem KSS; two as having the syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS); one as having KSS-MELAS overlap syndrome; and one as having Friedreich ataxia. Longitudinal testing was performed in seven children, and in all of them a progression of the hearing loss could be demonstrated. Audiological test results in all 12 children suggested cochlear as well as retrocochlear origin of the hearing loss presenting independently from the severity of hearing impairment. No correlation between the characteristics and degrees of hearing loss and the number and severity of clinical neurological symptoms could be found.

CONCLUSIONS

The present study demonstrated a high incidence (42%) of sensorineural hearing loss in children with mitochondrial encephalomyopathies. The progressive nature of the hearing impairment was confirmed by a significant correlation between the duration in years and severity of hearing loss in the children. The hearing loss does not have a prognostic value for the progression of the disorder. Based on our findings, we recommend regular audiometric examinations in patients with mitochondrial disorders.

Rearrangements of human mitochondrial DNA (mtDNA): new insights into the regulation of mtDNA copy number and gene expression

Mitochondria from patients with Kearns-Sayre syndrome harboring large-scale rearrangements of human mitochondrial DNA (mtDNA; both partial deletions and a partial duplication) were introduced into human cells lacking endogenous mtDNA. Cytoplasmic hybrids containing 100% wild-type mtDNA, 100% mtDNA with partial duplications, and 100% mtDNA with partial deletions were isolated and characterized. The cell lines with 100% deleted mtDNAs exhibited a complete impairment of respiratory chain function and oxidative phosphorylation. In contrast, there were no detectable respiratory chain or protein synthesis defects in the cell lines with 100% duplicated mtDNAs. Unexpectedly, the mass of mtDNA was identical in all cell lines, despite the fact that different lines contained mtDNAs of vastly different sizes and with different numbers of replication origins, suggesting that mtDNA copy number may be regulated by tightly controlled mitochondrial dNTP pools. In addition, quantitation of mtDNA-encoded RNAs and polypeptides in these lines provided evidence that mtDNA gene copy number affects gene expression, which, in turn, is regulated at both the post-transcriptional and translational levels.

Quantitative proton magnetic resonance spectroscopy of cerebral metabolic disturbances in patients with MELAS

Four patients with clinically and genetically defined MELAS were examined using quantitative localized proton magnetic resonance spectroscopy of the brain. Acute and chronic lesions were located in the occipital lobe and mostly characterized by strongly elevated concentrations of lactate (Lac) and glucose (GIc) as well as severely reduced concentrations of total N-acetylaspartyl compounds (tNAA, neuroaxonal markers), glutamate (Glu), and total creatine. These findings indicate a high degree of nonoxidative glycolysis reflecting either impaired oxidative energy metabolism or the use of anaerobic metabolism by infiltrating macrophages as well as damage or loss of viable neuroaxonal tissue. In contrast, glial cell populations, in particular astrocytes, seem to remain unaffected as evidenced by unchanged concentrations of myo-inositol (glial marker). In addition, all patients including one who never experienced a stroke-like episode showed elevated Lac and Glc as well as reduced tNAA and Glu in tissues appearing normal on MRI. These disturbances were stronger in cortical gray matter and cerebellum than in white matter and indicate that neuroaxonal damage is not restricted to structural lesions. The steady presence of Lac is consistent with a reduced capacity of the mitochondrial oxidative energy metabolism resulting from impaired respiratory chain function.

Characterization of the mitochondrial genome in childhood multiple sclerosis. III. Multiple sclerosis without optic neuritis and the non-LHON-associated genes

The higher maternal transmission of multiple sclerosis in familial cases and the coincidence of a MS-like phenotype with mitochondrial point mutations in patients with Leber's hereditary optic neuropathy has inspired a detailed assessment of the mitochondrial genome as an etiological factor in the pathogenesis of MS. To further elucidate the contribution of maternally transmitted mutations to MS susceptibility, we sequenced five protein- and all RNA-coding genes of the mtDNA from thirteen children with MS and twenty unaffected individuals. After excluding several synonymous mutations and common polymorphisms, a total of ten ambiguous missense or protein synthesis mutations were selected and analysed. By defining minimal criteria for pathogenity--incidence, location and degree of evolutionary conservation--we conclude that sequence variations in COII, ATPase6 and 8, ND3, or ND4L subunits of oxidative phosphorylation as well as in rRNA and tRNA genes are unlikely to increase susceptibility for the development of MS.

Characterization of the mitochondrial genome in childhood multiple sclerosis. II. Multiple sclerosis without optic neuritis and LHON-associated genes

The occurrence of mitochondrial mutations with primary pathogenic significance for Leber's hereditary optic neuropathy in patients with a multiple sclerosis-like phenotype and the preferential maternal transmission points to an involvement of the mitochondrial genome in conferring increased susceptibility to MS. To evaluate the link between MS and mtDNA variations we investigated a total of thirteen children with MS as well as twenty controls by sequencing eight mitochondrial encoded genes which are known to be the loci for LHON-associated mutations. Numerous synonymous nucleotide substitutions and common polymorphisms were excluded from comparative analyses. No primary LHON mutations were found. Secondary LHON mutations were identified more frequently in control subjects than in the children with MS. The remaining eight discrete missense mutations were chosen for further characterization. Only two of them were found in more than one patient. Our results suggest that nucleotide substitutions within the ND1, ND2, ND4, ND5, ND6, COI, COIII or cytochrome b genes of mtDNA do not contribute to the etiology of typical MS. However, the association of LHON mutations with visual impairment in MS as well as the relationship between phenotypic diversity in certain subgroups of patients with individual mtDNA genotypes merits further investigations.

Characterization of the mitochondrial genome in childhood multiple sclerosis. I. Optic neuritis and LHON mutations

The occurrence of optic neuropathy in patients with MS-like disorders who carry one of the pathogenetically significant LHON mutations as well as the higher incidence of maternal transmission in familial cases of MS support the hypothesis that mitochondrial genes may be implicated in susceptibility to MS. We sequenced the entire mtDNA of six children with MS who developed optic neuritis as early and prominent visual involvement. The analysis revealed a high degree of nucleotide variations relative to the standard mtDNA sequence. After excluding various synonymous nucleotide changes and common neutral polymorphisms, eight discrete novel missense mutations within the protein coding, tRNA or rRNA genes were detected. None of the eight polymorphic sites were found in common between the patients with MS. Of particular interest was the observation that five of six children carried a total of nine secondary LHON mutations at nucleotide positions 4216, 4917 or 13708. We conclude that variation in mtDNA is unlikely to contribute to genetic predisposition for MS. However, secondary LHON mutations may be regarded as additional risk factor for developing prominent optic nerve involvement. The association of individual sets of mtDNA variations with phenotypic presentation in certain subgroups of MS patients remains to be clarified.

Pyruvate dehydrogenase complex deficiency and altered respiratory chain function in a patient with Kearns-Sayre/MELAS overlap syndrome and A3243G mtDNA mutation

Combined alteration of the pyruvate dehydrogenase complex and respiratory chain function is described in a 21 year-old male patient with overlapping MELAS (mitochondrial encephalomyopathy, lactic acidosis, and 'stroke-like' episodes) and Kearns-Sayre syndrome. Progressive external ophthalmoplegia, pigmentary retinopathy and right bundle branch block were present when he experienced the first 'stroke-like' episode at 18 years old. The A>G tRNALeu(UUR) point mutation at nucleotide 3243 of the mitochondrial DNA was predominant in muscle tissue (79%) and present, but at lower levels in fibroblasts (49%) and blood cells (37%). Biochemical analysis revealed diminished activities of pyruvate dehydrogenase (23%) and respiratory chain complexes I and IV (57%, respectively) in muscle, but normal activities in the fibroblasts. Immunochemical studies of the muscular pyruvate dehydrogenase components showed normal content of E1alpha, E1beta and E2 protein. Molecular screening of the E1alpha gene did not indicate a nuclear mutation. These observations suggest that mitochondrial DNA defects may be associated with altered nuclear encoded enzymes which are actively imported into mitochondria and constitute components of the mitochondrial matrix. Biochemical workup of mitochondrial disorders should not be restricted to the respiratory chain even if mitochondrial DNA mutations are present.

S1 nuclease hybrid analysis of mitochondrial DNA amplified by long-distance PCR: rapid screening for small-scale rearrangements

We report on a method suitable for screening large regions (>3 kb) of mtDNA for structural changes of <500 bp and their localization. Heteroduplexes consisting of a wild-type and a mutant strand are cleaved by S1nuclease when single-stranded loops are present due to deletions or duplications/insertions. This strategy was successfully applied to screen the muscle mtDNA of 20 patients with mitochondrial encephalomyopathies. In three of them, an altered cleavage pattern was observed caused by a homoplasmic 9 bp deletion as shown by subsequent mapping and sequencing studies.

Hypoparathyroidism and deafness associated with pleioplasmic large scale rearrangements of the mitochondrial DNA: a clinical and molecular genetic study of four children with Kearns-Sayre syndrome

In four children with hypoparathyroidism and deafness as initial major manifestations of Kearns-Sayre syndrome, a unique pattern of mitochondrial DNA rearrangements was observed. Hypocalcemic tetany caused by PTH deficiency started between age of 6-13 y and was well controlled by small amounts of 1.25-(OH)2-cholecalciferol. Rearranged mitochondrial genomes were present in blood cells of all patients and consisted of partially duplicated and deleted molecules, created by the loss of 7813, 8348, 8587, and 9485 bp, respectively. The deletions were localized between the origins of replication of heavy and light strands and encompassed at least eight polypeptide-encoding genes and six tRNA genes. Sequence analysis revealed imperfect direct repeats present in all rearrangements flanking the break-points. The duplicated population accounted for 25-53% of the mitochondrial genome and was predominant to the deleted DNA (5-30%) in all cases. The proportions of the mutant populations (30-75%) correlated with the age at onset of the disease. We conclude that, unlike heteroplasmic deletions, pleioplasmic rearrangements may escape selection in rapid-dividing cells, distribute widely over many tissues, and thus cause multisystem involvement. Hypoparathyroidism and deafness might be the result of altered signaling pathway caused by selective ATP deficiency.

Cerebral adrenoleukodystrophy (ALD) in only one of monozygotic twins with an identical ALD genotype

We report on monozygotic twins with different clinical phenotypes of X-linked adrenoleukodystrophy. At the age of 10 years both boys were neurologically asymptomatic. The first cranial magnetic resonance examination showed normal findings in the first twin and parietooccipital demyelination in the second. The latter developed behavioral problems 9 months later, followed by visual impairment and gait ataxia. His cranial magnetic resonance image at the age of 11 years showed progressive demyelination. In contrast, neurological status and magnetic resonance images remained normal in the first twin. The same point mutation in exon 8 of the adrenoleukodystrophy gene (C2203T) was detected in both boys. All genotype examinations were consistent with the diagnosis of monozygotic twins, suggesting that some nongenetic factors may be important for different adrenoleukodystrophy phenotypes.

Cerebral Pseudallescheria mycosis after near-drowning

Scedosporium apiospermum, an anamorph of Pseudallescheria boydii, is a hyalohyphomycete which can be mistaken, histologically, for Aspergillus. S. apiospermum is clinically distinguished by resistance to most antifungals and its ability to cause invasive mycoses in immunocompetent patients. Here we present a typical case of lethal cerebral Pseudallescheria mycosis in a child after near-drowning.

[Retinitis pigmentosa in Kearns-Sayre syndrome resulting from mutation of mitochondrial DNA "de novo"]

We present a case of Kearns-Sayre syndrome diagnosed in a boy with retinitis pigmentosa ophthalmoplegia, ancephalomyopathy and cardiomyopathy. A single large-scale mtDNA deletion at very low level in the blood sample using Southern blot analyses and multiprimer DNA amplification was detected. This case demonstrates that retinitis pigmentosa may be due to genetic mitochondrial disturbances.

Deletion screening of mitochondrial DNA via multiprimer DNA amplification

We report an application of multiprimed polymerase chain reaction (PCR) which allows a rapid, nonradioactive detection of deletions in mitochondrial DNA using EDTA-blood and muscle samples. The use of two primer sets consisting of three forward and five reverse primers, respectively, allows a competitive PCR resulting in significant amplification products only in the presence of deletion-harbouring DNA species. Under the conditions described, deletions causing Kearns-Sayre syndrome (KSS) and progressive external ophthalmoplegia (PEO) have been successfully detected. The location of the primers on mitochondrial DNA used in this study should allow identification and localization of most of the large-scale deletions (i.e. more than 1 kb) of mitochondrial DNA reported so far.

Diffuse white matter disease in three children: an encephalopathy with unique features on magnetic resonance imaging and proton magnetic resonance spectroscopy

Amongst 21 children with unclassified white matter diseases three patients could be characterised by an identical clinical picture, magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (MRS) findings as a probably distinct entity. Following a normal early development they later showed rapidly progressive motor symptoms (ataxia, spasticity) leading to severe handicap within one or two years after onset. Later on bulbar symptoms, optic atrophy and epileptic seizures occurred. The MRI showed a diffuse homogeneous hypodensity of the white matter almost identical to the signal of the ventricles. MRS revealed a near total absence of N-acetylaspartate, choline and creatine and an increase of lactate and glucose. One girl and one boy were siblings, indicating an autosomal recessive trait.

DNA analysis of ornithine transcarbamylase deficiency

By analysing the restriction fragment length polymorphism (RFLP) detected by an ornithinetranscarbamylase (OTC) gene specific DNA probe, we followed the segregation of the defective gene in two families with OTC deficiency (X-linked disease). We were able to exclude some female family members as carriers. In one case a doubtful result obtained in a biochemical carrier detection test (by examining the renal orotic acid excretion after a protein load) could be clarified by DNA analysis. In every family with OTC deficiency, carrier detection should be biochemical with additional DNA analysis. Previous results of the biochemical carrier test should be controlled by DNA analysis, especially when "normal" results were obtained.

Genetic linkage study between the loci for Duchenne and Becker muscular dystrophy and nine X-chromosomal DNA markers

A set of nine polymorphic loci defined by DNA probes was studied for linkage with the disease locus in ten families with a history of Duchenne muscular dystrophy (DMD), and three families with a history of Becker muscular dystrophy (BMD). The results confirm DMD and BMD linkage to all marker loci and suggest closer linkage of several probes than hitherto detected. This will be of practical interest for risk calculations in affected families.

Rett syndrome--search for genetic markers

We have studied 8 girls with Rett syndrome, including 2 sisters. Their ages ranged from 1 to 26 years. The youngest patient presented with developmental delay and atypical infantile spasms. The oldest was the sister of a patient followed over a period of 13 years and showed the typical history and clinical picture of Rett syndrome. DNA from white blood cells of these patients was investigated for alterations in the OTC structural gene. As compared to normal control individuals no gross alterations occur in the OTC structural genes of patients with Rett's syndrome.