Oculopharyngodistal myopathy is a distinct entity: clinical and genetic features of 47 patients.

BACKGROUND: Oculopharyngodistal myopathy (OPDM) has been reported as a rare, adult-onset hereditary muscle disease with putative autosomal dominant and autosomal recessive inheritance. Patients with OPDM present with progressive ocular, pharyngeal, and distal limb muscle involvement. The genetic defect causing OPDM has not been elucidated. METHODS: Clinical and genetic findings of 47 patients from 9 unrelated Turkish families diagnosed with OPDM at the Department of Neurology, Istanbul Faculty of Medicine, between 1982 and 2009 were evaluated. RESULTS: The mean age at onset was around 22 years. Both autosomal dominant and autosomal recessive traits were observed, without any clear difference in clinical phenotype or severity. The most common initial symptom was ptosis, followed by oropharyngeal symptoms and distal weakness, which started after the fifth disease year. Intrafamilial variability of disease phenotype and severity was notable in the largest autosomal dominant family. Atypical presentations, such as absence of limb weakness in long-term follow-up in 9, proximal predominant weakness in 4, and asymmetric ptosis in 3 patients, were observed. Swallowing difficulty was due to oropharyngeal dysphagia with myopathic origin. Serum creatine kinase levels were slightly increased and EMG revealed myopathic pattern with occasional myotonic discharges. Myopathologic findings included rimmed and autophagic vacuoles and chronic myopathic changes. Importantly, a considerable proportion of patients developed respiratory muscle weakness while still ambulant. Linkage to the genetic loci for all known muscular dystrophies, and for distal and myofibrillar myopathies, was excluded in the largest autosomal dominant and autosomal recessive OPDM families. CONCLUSIONS: We suggest that OPDM is a clinically and genetically distinct myopathy.

Muscular dystrophies: diagnostic approaches in Hungary.

Muscular dystrophies are a genetically heterogeneous group of degenerative muscle disorders. This article focuses on two severe forms of muscular dystrophies and provides genetic data for a large cohort of Hungarian patients diagnosed within the last few years by the authors. The Duchenne/Becker muscular dystrophy (DMD/BMD) is caused by mutations in the dystrophin gene, which is located on chromosome Xp21. The genetic analysis of dystrophin is usually performed by multiplex polymerase chain reaction (PCR), which detects approximately 95% of all deletions but does not distinguish between one and two copies of the exons investigated. The present work, therefore, concentrates on the improvement of the diagnostic panel for the analysis of DMD/BMD in Hungary. Radioactively labelled cDNA probes, encompassing the whole dystrophin gene detect all the deletions and the analysis is quantitative. In addition, the new multiple ligation-dependent probe amplification (MLPA) technique was recently introduced that enabled more reliable and faster quantitative detection of the entire dystrophin gene. The genomic basis of facioscapulohumeral muscular dystrophy (FSHD) is associated with contraction of the D4Z4 repeat region in the subtelomere of chromosome 4q. In case of FSHD, molecular genetic criteria still have to be improved because of the complexity of the disorder.

Sequence analysis of Hungarian LHON patients not carrying the common primary mutations.

We describe sequence analysis of the mitochondrial DNA of five Hungarian patients diagnosed with probable LHON, who do not carry any of the three primary point mutations. We report three novel mutations, one of which might have a pathogenic role.

Congenital myasthenic syndrome (CMS) in three European kinships due to a novel splice mutation (IVS7 - 2 A/G) in the epsilon acetylcholine receptor (AChR) subunit gene.

Mutations in the epsilon-acetylcholine receptor (AChR epsilon) subunit gene cause congenital myasthenic syndromes (CMS) with postsynaptic neural transmission defects. We present 3 male and 2 female patients from three unrelated Croatian, Hungarian, and Russian families with autosomal recessive CMS. All patients manifested with variable degrees of ophthalmoparesis and generalized, fatiguable muscle weakness since birth or early infancy. Electrophysiological studies showed a decremental response in all patients indicating a neuromuscular transmission defect. Pyridostigmine treatment improved the proximal muscle weakness whereas the ophthalmoparesis remained unchanged in all patients. Analysis of the AChR epsilon subunit gene showed homozygosity for a novel splice site mutation of intron 7 epsilon(IVS7-2A/G) in the two Croatian siblings. epsilon-mRNA analysis by RT-PCR and direct sequencing revealed that exon 7 was spliced directly to exon 9 with skipping of exon 8. The Hungarian and Russian patients were heteroallelic carriers of the same mutation epsilon(IVS7-2A/G) and of a frameshifting mutation epsilon 70insG and epsilon 1293insG, respectively. We hypothesize that altered splice products may not be expressed as functional receptors at the cell surface. A haplotype analysis with polymorphic markers revealed a high degree of similarity for the epsilon(IVS7-2A/G) carrying allele in all families and may therefore indicate a common origin of the mutation.

Homozygosity (E140K) in SCO2 causes delayed infantile onset of cardiomyopathy and neuropathy.

OBJECTIVE: To report three unrelated infants with a distinctive phenotype of Leigh-like syndrome, neurogenic muscular atrophy, and hypertrophic obstructive cardiomyopathy. The patients all had a homozygous missense mutation in SCO2. BACKGROUND: SCO2 encodes a mitochondrial inner membrane protein, thought to function as a copper transporter to cytochrome c oxidase (COX), the terminal enzyme of the respiratory chain. Mutations in SCO2 have been described in patients with severe COX deficiency and early onset fatal infantile hypertrophic cardioencephalomyopathy. All patients so far reported are compound heterozygotes for a missense mutation (E140K) near the predicted CxxxC metal binding motif; however, recent functional studies of the homologous mutation in yeast failed to demonstrate an effect on respiration. METHODS: Here we present clinical, biochemical, morphologic, functional, MRI, and MRS data in two infants, and a short report in an additional patient, all carrying a homozygous G1541A transition (E140K). RESULTS: The disease onset and symptoms differed significantly from those in compound heterozygotes. MRI and muscle morphology demonstrated an age-dependent progression of disease with predominant involvement of white matter, late appearance of basal ganglia lesions, and neurogenic muscular atrophy in addition to the relatively late onset of hypertrophic cardiomyopathy. The copper uptake of cultured fibroblasts was significantly increased. CONCLUSIONS: The clinical spectrum of SCO2 deficiency includes the delayed development of hypertrophic obstructive cardiomyopathy and severe neurogenic muscular atrophy. There is increased copper uptake in patients' fibroblasts indicating that the G1541A mutation effects cellular copper metabolism.

MtDNA polymorphism in the Hungarians: comparison to three other Finno-Ugric-speaking populations.

Mitochondrial DNA sequence variation as well as restriction site polymorphisms were examined in 437 individuals from four Finno-Ugric-speaking populations. These included the Hungarians (Budapest region and the Csángós from Hungary and Romania), the Finns and two Saami groups from northeastern Finland (Inari Saami and Skolt Saami), and the Erzas from central Russia. The mtDNA data obtained in this study were combined with our previous data on Y chromosomal variation for eight different loci in these populations. The genetic variation observed among the Hungarians resembled closely that found in other European populations. The Hungarians could not be distinguished from the neighboring populations (e.g., the Austrians) any more than from their Finno-Ugric linguistic relatives.

A common mutation (epsilon1267delG) in congenital myasthenic patients of Gypsy ethnic origin.

OBJECTIVE: Mutation analysis of the acetylcholine receptor (AChR) epsilon subunit gene in patients with sporadic or autosomal recessive congenital myasthenic syndromes (CMS). BACKGROUND: The nicotinic AChR of skeletal muscle is a neurotransmitter-gated ion channel that mediates synaptic transmission at the vertebrate neuromuscular junction. Mutations in its gene may cause congenital myasthenic syndromes. A recently described mutation in exon 12 of the AChR epsilon subunit (epsilon1267delG) disrupts the cytoplasmic loop and the fourth transmembrane region (M4) of the AChR epsilon subunit. METHODS: Forty-three CMS patients from 35 nonrelated families were clinically classified as sporadic cases of CMS (group III according to European Neuromuscular Centre consensus) and were analyzed for epsilon1267delG by PCR amplification and sequence analysis. RESULTS: The authors report the complete genomic sequence and organization of the gene coding for the epsilon subunit of the human AChR (accession number AF105999). Homozygous epsilon1267delG was identified in 13 CMS patients from 11 independent families. All epsilon1267delG families were of Gypsy or southeastern European origin. Genotype analysis indicated that they derive from a common ancestor (founder) causing CMS in the southeastern European Gypsy population. Phenotype analysis revealed a uniform pattern of clinical features including bilateral ptosis and mild to moderate fatigable weakness of ocular, facial, bulbar, and limb muscles. CONCLUSIONS: The mutation epsilon1267delG might be frequent in European congenital myasthenic syndrome patients of Gypsy ethnic origin. In general, patients (epsilon1267delG) were characterized by the onset of symptoms in early infancy, the presence of ophthalmoparesis, positive response to anticholinesterase treatment, and the benign natural course of the disease.

[The importance of molecular genetic diagnosis of Martin-Bell disease in genetic counseling]. / A Martin-Bell-kór molekuláris genetikai kórismézésének jelentösége a genetikai tanácsadásban.

The female consultant had two mentally retarded boys from her two marriages. The clinical symptoms and Fra-X chromosomes indicated their Martin-Bell disease. The daughter of the consultant is healthy and Fra-X negative. She is pregnant and insisted on her molecular genetic diagnosis due to an international collaboration. Both affected brothers had FRAXA genes with a full mutation including more than 200 CGG methylated repeats. The consultant female was in the phase of premutation, however, her healthy daughter had two normal 50% methylated genes with 19 and 26 CGG repeats. Thus there is no recurrence risk for Martin-Bell disease in her fetus.

Examination of verocytotoxin producing capacity and determination of the presence of Shiga-like toxin genes in human Escherichia coli isolates.

A total of 93 wild type Escherichia coli of human origin (mostly representing intestinal isolates from Hungary) were examined for the presence of Shiga-like-toxin (SLT) genes using SLT-I, SLT-II and enterohemorrhagic E. coli (EHEC) specific DNA probes. The structural genes of the above specificity were labelled by random priming using 32-P-dCTP. E. coli strains investigated represented 16 serogroups: O1, O2, O4, O5, O6, O18, O25, O26, O45, O55, O111, O125, O126, O128, O157, O165, members of which were likely to produce verotoxin (VT) and strains of serotypes O11:NM, ONT:NM isolated from six haemorrhagic uraemic syndrome (HUS) patients. Out of these strains 51 were examined for in vitro VT production capacity. Only one strain (an O26:H11 from Germany) produced VT. This was also the only strain which proved to be positive with one of the SLT probes (SLT-II), and with the EHEC probe. From this strain a phage was isolated which was proven to be nonconvertible. These data support epidemiological and clinical observations about the very low occurrence or absence of EHEC in Hungary, in contrast to many European countries.

Xeroderma pigmentosum complementation group C cells remove pyrimidine dimers selectively from the transcribed strand of active genes.

We have measured the removal of UV-induced pyrimidine dimers from DNA fragments of the adenosine deaminase (ADA) and dihydrofolate reductase (DHFR) genes in primary normal human and xeroderma pigmentosum complementation group C (XP-C) cells. Using strand-specific probes, we show that in normal cells, preferential repair of the 5' part of the ADA gene is due to the rapid and efficient repair of the transcribed strand. Within 8 h after irradiation with UV at 10 J m-2, 70% of the pyrimidine dimers in this strand are removed. The nontranscribed strand is repaired at a much slower rate, with 30% dimers removed after 8 h. Repair of the transcribed strand in XP-C cells occurs at a rate indistinguishable from that in normal cells, but the nontranscribed strand is not repaired significantly in these cells. Similar results were obtained for the DHFR gene. In the 3' part of the ADA gene, however, both normal and XP-C cells perform fast and efficient repair of either strand, which is likely to be caused by the presence of transcription units on both strands. The factor defective in XP-C cells is apparently involved in the processing of DNA damage in inactive parts of the genome, including nontranscribed strands of active genes. These findings have important implications for the understanding of the mechanism of UV-induced excision repair and mutagenesis in mammalian cells.