Comprehensive genetic analyses of PLP1 in patients with Pelizaeus-Merzbacher disease applied by array-CGH and fiber-FISH analyses identified new mutations and variable sizes of duplications.

Pelizaeus-Merzbacher disease (PMD; MIM#312080) is a rare X-linked recessive neurodegenerative disorder. The main cause of PMD is alterations in the proteolipid protein 1 gene (PLP1) on chromosome Xq22.2. Duplications and point mutations of PLP1 have been found in 70% and 10-25% of all patients with PMD, respectively, with a wide clinical spectrum. Since the underlining genomic abnormalities are heterogeneous in patients with PMD, clarification of the genotype-phenotype correlation is the object of this study. Comprehensive genetic analyses using microarray-based comparative genomic hybridization (aCGH) analysis and genomic sequencing were applied to fifteen unrelated male patients with a clinical diagnosis of PMD. Duplicated regions were further analyzed by fiber-fluorescence in situ hybridization (FISH) analysis. Four novel and one known nucleotide alterations were identified in five patients. Five microduplications including PLP1 were identified by aCGH analysis with the sizes ranging from 374 to 951-kb. The directions of five PLP1 duplications were further investigated by fiber-FISH analysis, and all showed tandem duplications. The common manifestations of the disease in patients with PLP1 mutations or duplications in this study were nystagmus in early infancy, dysmyelination revealed by magnetic resonance imaging (MRI), and auditory brain response abnormalities. Although the grades of dysmyelination estimated by MRI findings were well correlated to the clinical phenotypes of the patients, there is no correlation between the size of the duplications and the phenotypic severity.

[Treatment approach to congenital myasthenic syndrome in a patient with acetylcholine receptor deficiency].

Congenital myasthenic syndromes (CMS) are rare heterogeneous disorders of neurotransmission caused by genetic defects of neuromuscular junction molecules. While CMS patients have been reported worldwide, in Japan there have been only a few descriptions of adult CMS patients with acetylcholinesterase (AChE) deficiency and slow channel syndrome. Herein, we report a Japanese CMS patient with acetylcholine receptor (AChR) deficiency, diagnosed during childhood, and our treatment approach to the patient. This 13-year-old Japanese boy had had severe myasthenic symptoms since infancy. Ptosis, his first symptom, appeared at 5 months and nasal voice was recognized at 2 years of age. AchR and anti-muscle-specific tyrosine kinase (Musk) antibody remained negative. A positive tensilon test and decremental response on electromyogram supported the diagnosis of sero-negative myasthenia gravis. Despite thymectomy and strong immunosuppressive therapy including steroid pulse and FK 506, he gradually deteriorated and became wheelchair bound. Genetic analyses for AchR, Rapsyn, Musk and AChE were negative. At age 11 years, a muscle biopsy was performed in the deltoid muscle for neuromuscular junction sampling. Electron microscopic and confocal microscopic analysis of endplates showed almost complete loss of AChR and the diagnosis of CMS with AChR deficiency was confirmed. All immunosuppressive therapies were discontinued. Instead, we started Ubretide and 3,4-diaminopyridine (DAP) after obtaining informed consent. Although not approved in Japan for this use, 3,4-DAP is reportedly effective in refractory cases of CMS. The patient experienced no side effects. Despite all of the objective data were improving, his subjective symptoms and ADL remained poor. There are still many challenges in the treatment of the patient.

POMT2 intragenic deletions and splicing abnormalities causing congenital muscular dystrophy with mental retardation.

BACKGROUND: Alpha-dystroglycanopathies are a group of congenital muscular dystrophies (CMDs) with autosomal recessive inheritance characterized by abnormal glycosylation of alpha-dystroglycan. Although six genetic causes have been identified (FKTN, POMGNT1, POMT1, POMT2, FKRP, and LARGE) many alpha-dystroglycanopathy patients remain without a genetic diagnosis after standard exon sequencing. To date POMT2 mutations have been identified in CMD cases with a wide range of clinical severities from Walker-Warburg syndrome to limb girdle muscular dystrophy without structural brain or ocular involvement. METHODS: We analyzed POMT2 in six CMD patients, who had severe diffuse muscle weakness, generalized joint contractures, microcephaly, severe mental retardation and elevated CK levels. Eye involvement was absent or limited to myopia or strabismus. We sequenced the coding regions of POMT2 using genomic DNA and cDNA generated from blood lymphocytes or B lymphoblastoid cell lines. Quantitative PCR analysis of genomic DNA was used to identify and determine the breakpoints of large deletions. RESULTS: We report five novel mutations in POMT2, four of which were outside of coding exons, two large genomic deletions and two intronic single base substitutions that induced aberrant mRNA splicing. CONCLUSIONS: Large scale DNA rearrangements (such as large deletions) and cryptic splice mutations, that can be missed on standard sequencing of genomic DNA, may be relatively common in POMT2. Additional techniques, such as sequencing of cDNA are needed to identify all mutations. These results also confirm that POMT2 mutations are an important cause of the less severe alpha-dystroglycanopathy phenotypes.

Protein O-mannosyltransferase activities in lymphoblasts from patients with alpha-dystroglycanopathies.

Defects in O-mannosylation of alpha-dystroglycan cause some forms of congenital muscular dystrophy (CMD), the so-called alpha-dystroglycanopathies. Six genes are responsible for these diseases with overlapping phenotypes. We investigated the usefulness of a biochemical approach for the diagnosis and investigation of the alpha-dystroglycanopathies using immortalized lymphoblasts prepared from genetically diagnosed and undiagnosed CMD patients and from control subjects. We measured the activities of protein O-mannose beta1,2-N-acetylglucosaminyltransferase 1 (POMGnT1) and protein O-mannosyltransferase (POMT). Lymphoblasts from patients harbouring known mutations in either POMGNT1 or POMT1 showed a marked decrease in POMGnT1 or POMT activity, respectively, compared to controls. Furthermore, we identified pathogenic mutations in POMGNT1, POMT1 or POMT2 in six previously genetically uncharacterised patients who had very low enzyme activity. In conclusion, the lymphoblast-based enzymatic assay is a sensitive and useful method (i) to select patients harbouring POMGNT1, POMT1 or POMT2 mutations; (ii) to assess the pathogenicity of new or already described mutations.

Nonsteroidal anti-inflammatory drug use does not affect short-term endoscopic and histologic outcomes after Helicobacter pylori eradication in patients with rheumatoid arthritis.

We evaluated the effects of the use of nonsteroidal anti-inflammatory drugs (NSAIDs) on endoscopic and histological findings in patients with rheumatoid arthritis (RA) before and after the eradication of Helicobacter pylori infection. Helicobacter pylori (H. pylori) eradication using lansoprazole 30 mg, amoxicillin 750 mg, and clarithromycin 200 mg twice daily for 1 week was conducted in 44 patients (mean age: 56.5 years) with RA. Using the updated Sydney system, endoscopic and histological findings of the greater curvature of the antrum, the greater curvature of the upper corpus, and the lesser curvature of the lower corpus were compared before and after eradication, for a mean follow-up period of 3.5 months. Overall, H. pylori eradication was successful in 32 patients (72.7%). Of these 32 patients, 23 were NSAID users. In the successful eradication group, (1) there was no significant change on endoscopic findings, including gastric erythema and erosion in all three regions irrespective of NSAIDs use; (2) of 17 active ulcers before eradication in NSAIDs users, all healed except for one duodenal ulcer that persisted, where one patient newly developed a gastric ulcer, one developed erosive duodenitis, and two developed reflux esophagitis, all in NSAID users; (3) neutrophil infiltration and chronic inflammation were significantly improved in all three regions after H. pylori eradication irrespective of use of NSAIDs, while atrophic change and intestinal metaplasia did not change. In the eradication failure group; (1) there was no significant change on endoscopic and histological findings in the three regions; (2) two of three ulcers present before eradication on NSAID users persisted even after eradication, and no new cases of gastric ulcer or erosive duodenitis occurred. In conclusion, over a mean follow-up period of 3.5 months, use of NSAIDs in Japanese patients with RA did not impair the healing process of gastric and duodenal ulcers nor did it affect the endoscopic and histological improvements associated with H. pylori eradication.