Masayuki Sasaki

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.

Successful treatment of severe asthma-associated plastic bronchitis with extracorporeal membrane oxygenation

We describe a case of near-fatal asthma requiring extracorporeal membrane oxygenation (ECMO). The patient presented with severe respiratory distress, which was not responsive to conventional pharmacological therapy. The patient also failed to respond to mechanical ventilation and thus was placed on venovenous ECMO for temporary pulmonary support. A fiberoptic bronchoscopy revealed that large amounts of thick bronchial secretions had occluded the main bronchus, which suggested plastic bronchitis secondary to asthma. Aggressive airway hygiene with frequent bronchoscopies and application of biphasic cuirass ventilation for facilitation of secretion clearance were performed to improve the patient’s respiratory status. The patient achieved a full recovery and suffered no neurological sequelae. This case illustrates that aggressive pulmonary hygiene with ECMO is a useful therapy for patients with asthma-associated plastic bronchitis.