Analysis of potential copy-number variations and genes associated with first-trimester missed abortion

Background

Copy number variation sequencing (CNV-seq) was proven to be a highly effective tool in studying of chromosomal copy number variations (CNVs) in prenatal diagnosis and post-natal cases with developmental abnormalities. However, the overall characteristics of missed abortion (MA) CNVs were largely unexplored.

Methods

We retrospectively analyzed the results of CNV-seq in first-trimester MA. The samples included were single pregnancy loss before 13 gestational weeks, and other potential factors affecting embryonic implantation and development had been excluded. Gene ontology and KEGG enrichment analysis was performed on the smallest overlapping regions (SORs) of high-frequency deletion/duplication.

Result

On the basis of strict inclusion and exclusion criteria, only 152 samples were included in our study. 77 (50.7%) samples displayed chromosome number abnormalities, 32 (21%) showed isolated CNVs, and 43 (28.3%) showed no CNVs. A total of 45 CNVs, ranging in size between 300 Kb and 126.56 Mb were identified, comprising 13 segmental aneuploidies CNVs, and 32 submicroscopic CNVs. Among these CNVs, we screened out four SORs (5q31.3, 5p15.33-p15.2, 8p23.3-p23.2, and 8q22.2-24.3), which were potentially associated with first-term MA. 16 genes were identified as potential miscarriage candidate genes through gene-prioritization analysis, including three genes (MYOM2, SDHA and TPPP) critical for embryonic heart or brain development.

Conclusion

We identified some potential candidate CNVs and genes associated with first-trimester MA. 5q31.3 duplications, 5p15.33-p15.2 deletions, 8p23.3-p23.2 deletions and 8p22.2-p24.3 duplications are four potential candidate CNVs. Additionally, MYOM2, SDHA and TPPP are potential genes associated with first-trimester MA.

Dysferlin interacts with calsequestrin-1, myomesin-2 and dynein in human skeletal muscle

Dysferlinopathies are a group of progressive muscular dystrophies characterized by mutations in the gene DYSF. These mutations cause scarcity or complete absence of dysferlin, a protein that is expressed in skeletal muscle and plays a role in membrane repair. Our objective was to unravel the proteins that constitute the dysferlin complex and their interaction within the complex using immunoprecipitation assays (IP), blue native gel electrophoresis (BN) in healthy adult skeletal muscle and healthy cultured myotubes, and fluorescence lifetime imaging-fluorescence resonance energy transfer (FLIM-FRET) analysis in healthy myotubes. The combination of immunoprecipitations and blue native electrophoresis allowed us to identify previously reported partners of dysferlin - such as caveolin-3, AHNAK, annexins, or Trim72/MG53 - and new interacting partners. Fluorescence lifetime imaging showed a direct interaction of dysferlin with Trim72/MG53, AHNAK, cytoplasmic dynein, myomesin-2 and calsequestrin-1, but not with caveolin-3 or dystrophin. In conclusion, although IP and BN are useful tools to identify the proteins in a complex, techniques such as fluorescence lifetime imaging analysis are needed to determine the direct and indirect interactions of these proteins within the complex. This knowledge may help us to better understand the roles of dysferlin in muscle tissue and identify new genes involved in muscular dystrophies in which the responsible gene is unknown.