An Extended Targeted Copy Number Variation Detection Array Including 187 Genes for the Diagnostics of Neuromuscular Disorders

Background: Our previous array, the Comparative Genomic Hybridisation design (CGH-array) for nemaline myopathy (NM), named the NM-CGH array, revealed pathogenic copy number variation (CNV) in the genes for nebulin (NEB) and tropomyosin 3 (TPM3), as well as recurrent CNVs in the segmental duplication (SD), i.e. triplicate, region of NEB (TRI, exons 82-89, 90-97, 98-105). In the light of this knowledge, we have designed and validated an extended CGH array, which includes a selection of 187 genes known to cause neuromuscular disorders (NMDs). Objective: Our aim was to develop a reliable method for CNV detection in genes related to neuromuscular disorders for routine mutation detection and analysis, as a much-needed complement to sequencing methods. Methods: We have developed a novel custom-made 4×180 k CGH array for the diagnostics of NMDs. It includes the same tiled ultra-high density coverage of the 12 known or putative NM genes as our 8×60 k NM-CGH-array but also comprises a selection of 175 additional genes associated with NMDs, including titin (TTN), at a high to very high coverage. The genes were divided into three coverage groups according to known and potential pathogenicity in neuromuscular disorders. Results: The array detected known and putative CNVs in all three gene coverage groups, including the repetitive regions of NEB and TTN. Conclusions: The targeted neuromuscular disorder 4×180 k array-CGH (NMD-CGH-array v1.0) design allows CNV detection for a broader spectrum of neuromuscular disorders at a high resolution. © 2018 - IOS Press and the authors. All rights reserved.Peer reviewe

An unusual ryanodine receptor 1 (RYR1) phenotype: Mild calf-predominant myopathy

Objective To identify the genetic defect causing a distal calf myopathy with cores.Methods Families with a genetically undetermined calf-predominant myopathy underwent detailed clinical evaluation, including EMG/nerve conduction studies, muscle biopsy, laboratory investigations, and muscle MRI. Next-generation sequencing and targeted Sanger sequencing were used to identify the causative genetic defect in each family.Results A novel deletion-insertion mutation in ryanodine receptor 1 (RYR1) was found in the proband of the index family and segregated with the disease in 6 affected relatives. Subsequently, we found 2 more families with a similar calf-predominant myopathy segregating with unique RYR1-mutated alleles. All patients showed a very slowly progressive myopathy without episodes of malignant hyperthermia or rhabdomyolysis. Muscle biopsy showed cores or core-like changes in all families.Conclusions Our findings expand the spectrum of RYR1-related disorders to include a calf-predominant myopathy with core pathology and autosomal dominant inheritance. Two families had unique and previously unreported RYR1 mutations, while affected persons in the third family carried 2 previously known mutations in the same dominant allele.</div

Distribution and reproduction of the Arctic ctenophore Mertensia ovum in the Baltic Sea

Species identification based on morphological characteristics has caused misidentifications and led to twisted views of abundances and roles of ctenophores. Based on extensive field studies from 2007 to 2010, the occurrence of the arctic ctenophore Mertensia ovum was genetically verified in the southern, central and northern Baltic Sea, and its egg production, distribution and abundance were studied in relation to physical factors. Genetic analyses indicate that M. ovum is by far the most abundant small ctenophore in the Baltic Sea. Specimens from a 20 yr old ctenophore collection were also genetically identified as M. ovum, contrary to their previous morphological identification as another ctenophore species, Pleurobrachia pileus. Thus, earlier reports on P. pileus in the Baltic Sea may actually refer to M. ovum. The abundance of M. ovum was regulated by both salinity and temperature, with highest abundances found in sea areas and water layers at temperatures 5.5 and oxygen levels >4 ml l-1. During summer, the highest abundances of ctenophores and their eggs were found near the halocline, while the distribution was more uniform throughout the water column during winter. Only ctenophores >3.5 mm (oral-aboral length) produced eggs in the experiments, with an average rate of 2.2 eggs ind.-1 d-1. Finally, comparison with published data from the 1980s (assuming that those data refer to M. ovum) indicates that the present-day ctenophore abundance is ~80% lower in the north and ~55% higher in the southern parts of the Baltic Sea, due to reasons yet to be established