Epidemic myalgia and myositis associated with human parechovirus type 3 infections occur not only in adults but also in children: findings in Yamagata, Japan, 2014.

We previously reported an association between human parechovirus type 3 (HPeV3) and epidemic myalgia with myositis in adults during summers in which an HPeV3 outbreak occurred in children. However, this disease association has not yet been reported elsewhere. We have since continued our surveillance to accumulate data on this disease association and to confirm whether myalgia occurs in children as well as adults. Between June and August 2014, we collected 380 specimens from children with infectious diseases. We also collected clinical specimens from two adult and three paediatric patients suspected of myalgia. We then performed virus isolation and reverse-transcription-PCR using the collected specimens. We detected HPeV3 in 26 children with infectious diseases, which we regarded as indicating an outbreak. We also confirmed HPeV3 infection in all patients suspected of myalgia. In particular the symptoms in two boys, complaining of myalgia and fever, closely matched the criteria for adult myalgia. Based on our findings from 2008, 2011 and 2014, we again urge that clinical consideration be given to the relationship between myalgia and HPeV3 infections during HPeV3 outbreaks in children. Furthermore, our observations from 2014 suggest that epidemic myalgia and myositis occur not only in adults but also in children.

A novel intronic mutation of the TAZ ( G4.5) gene in a patient with Barth syndrome: creation of a 5' splice donor site with variant GC consensus and elongation of the upstream exon.

Mutation analysis of the TAZ ( G4.5) gene was performed on a patient with Barth syndrome. The reverse transcription/polymerase chain reaction procedure showed aberrant splicing and elongation of exon 3 because of the insertion of 106 bases (IVS3+1 to +106) between exons 3 and 4. The genomic DNA revealed an intronic mutation four bases downstream from the new cleavage site (IVS3+110G-->A). The IVS3+110G-->A mutation created a novel 5' splice site that showed GC but not GT, and the additional splice site was used preferentially over the upstream authentic slice site. This is a new type of splicing mutation responsible for a human genetic disease.

Three families with autosomal dominant nephrogenic diabetes insipidus caused by aquaporin-2 mutations in the C-terminus.

The vasopressin-regulated water channel aquaporin-2 (AQP2) is known to tetramerize in the apical membrane of the renal tubular cells and contributes to urine concentration. We identified three novel mutations, each in a single allele of exon 4 of the AQP2 gene, in three families showing autosomal dominant nephrogenic diabetes insipidus (NDI). These mutations were found in the C-terminus of AQP2: a deletion of G at nucleotide 721 (721 delG), a deletion of 10 nucleotides starting at nucleotide 763 (763-772del), and a deletion of 7 nucleotides starting at nucleotide 812 (812-818del). The wild-type AQP2 is predicted to be a 271-amino acid protein, whereas these mutant genes are predicted to encode proteins that are 330-333 amino acids in length, because of the frameshift mutations. Interestingly, these three mutant AQP2s shared the same C-terminal tail of 61 amino acids. In Xenopus oocytes injected with mutant AQP2 cRNAs, the osmotic water permeability (Pf) was much smaller than that of oocytes with the AQP2 wild-type (14%-17%). Immunoblot analysis of the lysates of the oocytes expressing the mutant AQP2s detected a band at 34 kD, whereas the immunoblot of the plasma-membrane fractions of the oocytes and immunocytochemistry failed to show a significant surface expression, suggesting a defect in trafficking of these mutant proteins. Furthermore, coinjection of wild-type cRNAs with mutant cRNAs markedly decreased the oocyte Pf in parallel with the surface expression of the wild-type AQP2. Immunoprecipitation with antibodies against wild-type and mutant AQP2 indicated the formation of mixed oligomers composed of wild-type and mutant AQP2 monomers. Our results suggest that the trafficking of mutant AQP2 is impaired because of elongation of the C-terminal tail, and the dominant-negative effect is attributed to oligomerization of the wild-type and mutant AQP2s. Segregation of the mutations in the C-terminus of AQP2 with dominant-type NDI underlies the importance of this domain in the intracellular trafficking of AQP2.

Growth of two children after six months interruption of GH therapy.

We describe two short boys with normal GH responses to the stimuli in whom GH therapy was interrupted for 6 months. Their growth rates before and after the interruption, and after re-administration of GH were evaluated. Height velocity (HV) in case 1 before and after the interruption was 6.6 cm/y and 5.0 cm/y, respectively. HV was not increased (5.0 cm/y) by re-initiation of GH therapy despite the high serum IGF-1 level. Height velocity (HV) in case 2 before and after the interruption was 5.6 cm/y and 3.6 cm/y, respectively. HV was slightly increased to 4.1 cm/y by re-administration of GH, but it was far below the pretreatment value. Serum IGF-1 was increased by GH in this case as well. We conclude that re-acceleration of growth by re-administration of GH after interruption of therapy, as seen in classical GHD patients, may not be expected in normal short children.