Mutation spectrum of 260 dystrophinopathy patients from Turkey and important highlights for genetic counseling.

We genetically evaluated 260 dystrophinopathy patients from Turkey. Karyotyping as an initial test in female patients, followed stepwise by multiplex ligation-dependent probe amplification and by targeted next-generation sequencing of DMD revealed definitive genetic diagnoses in 214 patients (82%), with gross deletions/duplications in 153 (59%), pathogenic sequence variants in 60 (23%), and X-autosome translocation in one. Seven of the gross and 27 of the sequence variants found novel. In silico prediction, co-segregation and transcript assays supported the pathogenic nature of the novel silent (p.Lys534=) and the splice site (c.4345-12C>G) alterations. From a total of 189 singleton cases, 154 (82%) had pathogenic alterations. From 138 of those who had maternal carrier testing, 68 out of 103 (66%) showed gross and 11 out of 35 (31%) showed small pathogenic variants. This suggests that the de novo occurrences in DMD appear approximately 2.1 times more frequently in meiotic unequal crossing-over than in uncorrected replication errors. Our study also disclosed three mothers as obligate gonadal mosaic carriers. Family-based investigation of dystrophinopathy patients is crucial for the ascertainment of novel or rare variants and also for counseling and follow-up care of the families.

Clinical characteristics and course of spinal cord involvement in Behçet's disease.

Parenchymal neurological involvement in Behçet's disease (p-NBD) usually presents with a brainstem syndrome; occasionally spinal cord may also be involved. Files of patients with Behçet's disease and spinal cord involvement were reviewed retrospectively, in comparison with other types of p-NBD. Amongst 216 patients with p-NBD, 24 had spinal cord involvement (11%). Most commonly patients presented with sensory-motor symptoms, sphincter and/or sexual dysfunction evolving over days. Four of 10 patients showed single or multiple cervical and/or dorsal lesions on spinal MRI's and one showed dorsal atrophy. Although the clinical picture was variable, it tended to be severe; seven cases had primary progressive course, 11 cases had a secondary progressive course after initial attack(s), four had attacks with severe residual sequela and two had improvement after attacks. After a median follow-up period of 67 months, eight were independent and 14 were dead or dependent, whereas amongst the remaining patients with p-NBD, 113 patients were independent and 56 patients were dead or dependent (P < 0.05). Our study suggests that spinal cord involvement has even worse prognosis compared with other types of p-NBD. Therefore, recognition of spinal cord involvement in Behçet's patients should prompt early vigorous treatment.

Clinical comparison of anti-MuSK- vs anti-AChR-positive and seronegative myasthenia gravis.

We compared 65 anti-acetylcholine receptor (AChR)-negative myasthenia gravis (MG) patients, including 32 anti-muscle-specific tyrosine kinase (MuSK)-positive (49%) and 33 anti-MuSK-negative (seronegative) (51%) patients, with 161 anti-AChR-positive MG patients. The anti-MuSK-positive group had a higher frequency of bulbar involvement and respiratory crises. The seronegative group was in between the anti-MuSK positive and the anti-AChR positive groups, being closer to the latter, with regard to the severity of the disease. At the end of follow-up, the outcome of the anti-MuSK-positive patients was not different from that of the anti-AChR-positive patients, although their maintenance corticosteroid dose was higher. The seronegative patients had better outcome than the other two groups.

Silent neurological involvement in Behçet's disease.

OBJECTIVE: The aim of this study was to determine the long term clinical course and prognosis of subclinical ('silent') neurological involvement in Behçet's disease (BD). METHODS: We included patients with BD who did not have any neurological complaints other than headache, dizziness or other non-specific complaints, that showed abnormal neurological findings (Silent Group). We compared these patients with the patients with overt parenchymal neuro-Behçet's disease (Overt Group). Cases with at least 8 years of follow-up were included. RESULTS: There were 22 patients in the Silent Group (15M, 7F), with a mean follow-up of 12.8 +/- 4 years. Magnetic resonance imaging was abnormal in 8 of 21 patients, while neuropsychological testing revealed mild abnormalities in 15 of 20 patients. During the follow up period, 3 patients of the Silent Group had 4 overt neurological attacks. In the last visit, 21 patients were independent, while one that had previously developed overt neurological attack was deceased. The Overt Group consisted of 51 patients (45M, 6F). In the Overt Group the ratio of males was higher, nearing a marginal significance (p = 0.051); whereas age at onset of BD, and frequency of other organ manifestations of BD were not different. In the Overt Group at the final visit, 19 patients were independent (37%), while the remaining were either dependent to others, or deceased, which was significantly higher when compared to the Silent Group(p=0.005). CONCLUSION: Silent neurological involvement in BD seems to represent a milder form of the disease, since the mortality and disability rate in this group is significantly low.

Parkin expression in human skeletal muscle.

Parkin is known to be present in human neurons and peripheral nerves. Using an antibody against parkin protein we have now demonstrated that parkin is also expressed in the sarcoplasm and sarcolemmal region of human skeletal muscle fibres. We have also found different age-related patterns of expression with increase in intensity and organization of distribution at older ages. These findings suggest a change in the functional role of parkin in skeletal muscle with ageing and may contribute to understanding the mechanisms of muscle aging.

Parkin expression in muscle from three patients with autosomal recessive Parkinson's disease carrying parkin mutation.

Absence of parkin has been shown to cause the downturned wing phenotype and severe disruption of myofibrils and mitochondrial abnormalities in parkin null mutant drosophila. The present report refers to studies on 3 patients with autosomal recessive Parkinson's disease with mild histopathological changes in muscle and a 'G' deletion at the exon9/intron9 junction or exon 3 deletion in the parkin gene. Using an antibody against a peptide corresponding to sequence number 305-323 of the human parkin protein it was demonstrated that parkin was expressed in skeletal muscle of these patients and that its distribution was similar to that in normal muscles. The mild nature of the histopathological changes, especially in the young patients, in the presence of parkin mutations may be due to residual E3-ubiquitin ligase activity of the mutant protein, to existence of muscle-specific splice-variants or to the relative functional insignificance of parkin in human muscle fibres. Further investigation of parkin expression in skeletal muscle is warranted.

Absence of KIF1B mutation in a large Turkish CMT2A family suggests involvement of a second gene.

BACKGROUND: Charcot-Marie-Tooth disease type 2A (CMT2A) was assigned to a 19.3-cM region on chromosome 1p35-36. A missense mutation in the kinesin family member 1B gene (KIF1B) was reported in a single CMT2A family. OBJECTIVE: To report the clinical and genetic data of a Turkish family with CMT2A. METHODS: Linkage to CMT2 loci was investigated in the family. Haplotype analysis of the CMT2A region was completed using additional single-nucleotide polymorphism and short tandem repeat markers. The KIF1B gene was sequenced on genomic DNA and cDNA in two patients. RESULTS: A recombination event narrowed the CMT2A locus to a 9.3-cM region flanked by D1S160 and D1S434. No mutation in KIF1B was found. CONCLUSION: The exclusion of KIF1B gene mutations in this family suggests the involvement of another CMT2A gene in the linked region.

Cranial MRI in Behçet's disease: 134 examinations of 98 patients.

Two observers, blinded to the patient's neurological status, reviewed 134 MRI studies of 98 consecutive patients with Behçet's disease (BD), to define imaging patterns and to look for any relationship between the MRI findings and the timing of the examination in patients with differing courses of disease. There were 43 patients with overt parenchymal central nervous system (CNS) involvement, 22 with attacks and remissions, 15 with secondary progressive and six with primary progressive disease; 14 had raised intracranial pressure (RICP). Of the remaining 41 patients without specific neurological complaints, 16 had abnormalities on examination (silent CNS involvement) and 25 did not. During an acute CNS attack, the most common finding was a large lesion in the brain-stem or basal ganglia, extending to the diencephalon. On MRI performed after remission of an acute attack or during secondary progression, the same sites were affected, but the lesions were smaller or scattered, with less clearly defined margins. In primary progressive disease or silent CNS involvement, the cerebral white matter was most commonly involved, but almost half the MRI studies were normal. The brain parenchyma was abnormal in only one of the patients with RICP. MRI was normal in all but three patients without clinical CNS involvement, in whom it showed a few millimetric white-matter lesions. Brain-stem atrophy was seen in 15 patients examined >1 year after an initial parenchymal CNS episode, with secondary progressive cases predominating.

Distribution of extremity muscle weakness in myasthenia gravis: sparing of tibialis anterior muscle.

We evaluated the distribution of muscle weakness in 70 myasthenia gravis (MG) patients, using the MRC scale. Extensors in the upper extremities and proximal flexors in the lower extremities (LE) were found to be weak. Tibialis anterior muscle was rarely affected and only when there was substantial weakness in LE proximal muscles. Attention to this distribution may help in differentiating MG, particularly MG with only limb weakness, from muscular dystrophies.

The range of chronic demyelinating neuropathy of infancy: a clinico-pathological and genetic study of 15 unrelated cases.

The concept of Dejerine-Sottas disease, which corresponds to presumed recessive demyelinating neuropathies with onset in infancy, remains controversial. To learn more on the subject, we performed a clinico-pathological and molecular genetic study in 15 unrelated patients with the Dejerine-Sottas phenotype seen over a 16 year period. There were 12 females and 3 males, born to asymptomatic parents. Study of the PMP22, P0 and Egr2 genes was performed in all cases and 14 underwent a nerve biopsy. First manifestations of neuropathy occurred before 3 years of age in all patients. An inherited disorder was suspected in 10 patients, because of their family history and/or disclosure of a molecular genetic defect in 4 of them. One patient had a recessively transmitted homozygous point mutation (Arg157Trp) of the PMP22 gene. A heterozygous duplication of the 17p11.2-12 segment was detected in one offspring of a consanguineous marriage. One patient carried a "de novo" heterozygous Ser72Leu substitution in the PMP22. A heterozygous double mutation of the P0 gene including a "de novo" Val42 deletion and an Ala221Thr substitution, maternally inherited, were found in an apparently sporadic case. No mutation of the Egr2 gene was identified. A neuropathy with focally folded myelin sheaths (CMT4B) was diagnosed in the nerve biopsy specimens of two patients. In five patients, the clinico-pathological findings along with the absence of an identified mutation suggested the diagnosis of chronic inflammatory demyelinating polyneuropathy of infantile onset. Our findings illustrate the genetic heterogeneity of cases with identified mutations, the scarcity of cases with "demonstrated" recessive transmission and the likelihood of early acquired chronic inflammatory demyelinating polyneuropathy in several patients.

Mapping of the second Friedreich's ataxia (FRDA2) locus to chromosome 9p23-p11: evidence for further locus heterogeneity.

Friedreich's ataxia (FRDA), the most-common form of autosomal recessive ataxia, is inherited in most cases by a large expansion of a GAA triplet repeat in the first intron of the frataxin (X25) gene. Genetic heterogeneity in FRDA has been previously reported in typical FRDA families that do not link to the FRDA locus on chromosome 9q13. We report localization of a second FRDA locus (FRDA2) to chromosome 9p23-9p11, and we provide evidence for further genetic heterogeneity of the disease, in a family with the classic FRDA phenotype.

Mutations in Kir2.1 cause the developmental and episodic electrical phenotypes of Andersen's syndrome.

Andersen's syndrome is characterized by periodic paralysis, cardiac arrhythmias, and dysmorphic features. We have mapped an Andersen's locus to chromosome 17q23 near the inward rectifying potassium channel gene KCNJ2. A missense mutation in KCNJ2 (encoding D71V) was identified in the linked family. Eight additional mutations were identified in unrelated patients. Expression of two of these mutations in Xenopus oocytes revealed loss of function and a dominant negative effect in Kir2.1 current as assayed by voltage-clamp. We conclude that mutations in Kir2.1 cause Andersen's syndrome. These findings suggest that Kir2.1 plays an important role in developmental signaling in addition to its previously recognized function in controlling cell excitability in skeletal muscle and heart.

Cerebral vasculitis and ischaemic stroke in Behçet's disease: report of one case and review of the literature.

INTRODUCTION: Behçet's disease (BD) is a multisystemic, recurrent, inflammatory disorder. Neurological involvement is well-known but cerebral vasculitis and ischaemic stroke are unusual. CASE DESCRIPTION: A 43-year-old male patient presented with acute left hemiparesis, he had recurrent oral aphthae and scrotal ulcerations. Two episodes of transient brainstem ischaemia and an episode of right hemiparesis were reported in the past 2 years. Cranial magnetic resonance (MR) imaging showed a right striatocapsular infarction and multiple segmental stenosis, fusiform enlargement and beading of the arteries of the polygone of Willis were seen on angiography. Cerebro-spinal fluid (CSF) examination disclosed lymphocytic pleocytosis. Skin pathergy test was positive. A diagnosis of BD with cerebral vasculitis was made and immunosuppressive therapy was started. Some improvement of the arterial lesions on MR angiography and normalization of CSF were observed after 1 year of treatment. DISCUSSION: Low grade chronic meningo-encephalitis is the core neuropathological process in neuro-Behçet's disease. Nevertheless BD is a systemic disease known to cause vasculitis and can exceptionally lead to cerebral vasculitis and brain infarction. While BD is usually not part of the differential diagnosis of cerebral vasculitis, it should be borne in mind especially in endemic areas of the disease and in patients from these areas.

Anti-alpha B-crystallin immunoreactivity in inflammatory nervous system diseases.

alpha B-Crystallin, a small heat shock protein, is an immunodominant antigen with increased tissue expression in demyelination. To investigate the humoral response against alpha B-crystallin, the sera and CSF samples of patients with multiple sclerosis (MS), Guillain-Barré syndrome (GBS), neuro-Behçet's disease (NBD) and other non-inflammatory neurological diseases (NIND) were screened by enzyme-linked immunosorbent assay for anti-alpha B-crystallin IgG and IgM antibodies. Serum and CSF IgG antibody responses to alpha B-crystallin were significantly elevated only in NBD patients (serum IgG, NBD 1.29 +/- 0.49 vs. NIND 0.95 +/- 0.39, P = 0.01; CSF IgG, NBD 1.22 +/- 0.64 vs. NIND 0.81 +/- 0.35, P = 0.01). Similarly, high serum IgM antibody titres were also detected in NBD (1.83 +/- 0.72 vs. 1.16 +/- 0.49, P = 0.0005) and in MS (1.57 +/- 1.07, P = 0.046), whereas elevated CSF IgM responses were observed only in GBS (2.09 +/- 1.09 vs. 1.41 +/- 0.7, P = 0.007). Humoral responses against alpha B-crystallin are increased in NBD and GBS, which may implicate this central nervous system antigen in the causation and pathogenesis of these inflammatory nervous system disorders.

Deletion pattern in the dystrophin gene in Turks and a comparison with Europeans and Indians.

Patterns of dystrophin gene deletions in DMD/BMD patients were compared in four populations: Turks (n = 146 deletions), Europeans (n = 838), North Indians (n = 89), and Indians from all over India (n = 103). Statistical tests revealed that there are differences in the proportions of small deletions. In contrast, the distribution of deletion breakpoints and the frequencies of specific deletions commonly observed in the four populations are not significantly different. The variations strongly suggest that sequence differences exist in the introns, and the differences are in agreement with genetic distances among populations. The similarities suggest that some intronic sequences have been conserved and that those will trigger recurrent deletions, since it is unlikely that gene flow would disperse the deleted chromosomes, which vanish from the gene pool in a few generations.

Mutational analysis and genotype/phenotype correlation in Turkish Charcot-Marie-Tooth Type 1 and HNPP patients.

The major Charcot- Marie-Tooth Type 1 (CMT1) locus, CMT1A, and Hereditary neuropathy with liability to pressure palsies (HNPP) cosegregate with a 1.5-Mb duplication and a 1.5-Mb deletion, respectively, in band 17p11.2. Point mutations in peripheral myelin gene 22 (PMP22), myelin protein zero (MPZ), and connexin 32 (Cx32) have been reported in CMT1, and in PMP22 in HNPP patients without deletion. We have screened 54 CMT1 patients, of variable clinical severity, and 25 HNPP patients from Turkey, with no duplication or deletion, for mutations in the PMP22 and Cx32 genes. A novel frameshift mutation affecting the second extracellular domain of PMP22 was found in an HNPP patient, while a point mutation in the second transmembrane domain of the protein was detected in a CMT1 patient. Two point mutations affecting different domains of Cx32 were identified in two CMTX patients. Another patient was found to carry a polymorphism in a non-conserved codon of the Cx32 gene. The clinical phenotypes of the patients correlate well with the effect of the mutation on the protein.

Clinical patterns of neurological involvement in Behçet's disease: evaluation of 200 patients. The Neuro-Behçet Study Group.

In order to define the patterns of neurological involvement in Behçet's disease and to assess prognostic factors, 558 files of the neuro-Behçet out-patient clinic were reviewed. Those patients without any evidence of objective neurological involvement as well as the patients with other possible explanations for the neurological picture, and cases not fulfilling the criteria for Behçet's disease were excluded. The remaining 200 cases (155 male, 45 female) were evaluated: 162 had parenchymal CNS involvement (brainstem or 'brainstem +' involvement in 51%, spinal cord involvement in 14%, hemispheric involvement in 15% and isolated pyramidal signs in 19%) while 38 had secondary or non-parenchymal CNS involvement. In the first group the most common findings were pyramidal signs, hemiparesis, behavioural changes and sphincter disturbance, whereas in the second group the syndrome of raised intracranial pressure due to dural sinus thrombosis was the main clinical manifestation. In 60% of the cases with parenchymal involvement, CSF was hypercellular and/or had an elevated protein level, whereas in cases with non-parenchymal involvement the CSF was usually normal except for the elevated pressure. In more than half of the patients with parenchymal involvement, MRI showed brainstem and/or basal ganglion lesions. Forty-one per cent of the cases had a course with at least one attack and remission, another 28% also had attack(s) but showed secondary progression, 10% had primary progression and 21% had silent neurological involvement. Survival analysis was performed in patients who had at least a 3-year duration of neurological disease. Parenchymal involvement, elevated protein and/or pleocytosis in the CSF, 'brainstem +' type involvement, primary or secondary progressive course and relapse during steroid tapering were all associated with a poorer prognosis.