Targeted genetic analysis in a large cohort of familial and sporadic cases of aneurysm or dissection of the thoracic aorta.

PURPOSE: Thoracic aortic aneurysm/aortic dissection (TAAD) is a disorder with highly variable age of onset and phenotype. We sought to determine the prevalence of pathogenic variants in TAAD-associated genes in a mixed cohort of sporadic and familial TAAD patients and identify relevant genotype-phenotype relationships. METHODS: We used a targeted polymerase chain reaction and next-generation sequencing-based panel for genetic analysis of 15 TAAD-associated genes in 1,025 unrelated TAAD cases. RESULTS: We identified 49 pathogenic or likely pathogenic (P/LP) variants in 47 cases (4.9% of those successfully sequenced). Almost half of the variants were in nonsyndromic cases with no known family history of aortic disease. Twenty-five variants were within FBN1 and two patients were found to harbor two P/LP variants. Presence of a related syndrome, younger age at presentation, family history of aortic disease, and involvement of the ascending aorta increased the risk of carrying a P/LP variant. CONCLUSION: Given the poor prognosis of TAAD that is undiagnosed prior to acute rupture or dissection, genetic analysis of both familial and sporadic cases of TAAD will lead to new diagnoses, more informed management, and possibly reduced mortality through earlier, preclinical diagnosis in genetically determined cases and their family members.

Targeted next-generation sequencing makes new molecular diagnoses and expands genotype-phenotype relationship in Ehlers-Danlos syndrome.

PURPOSE: Ehlers-Danlos syndrome (EDS) comprises a group of overlapping hereditary disorders of connective tissue with significant morbidity and mortality, including major vascular complications. We sought to identify the diagnostic utility of a next-generation sequencing (NGS) panel in a mixed EDS cohort. METHODS: We developed and applied PCR-based NGS assays for targeted, unbiased sequencing of 12 collagen and aortopathy genes to a cohort of 177 unrelated EDS patients. Variants were scored blind to previous genetic testing and then compared with results of previous Sanger sequencing. RESULTS: Twenty-eight pathogenic variants in COL5A1/2, COL3A1, FBN1, and COL1A1 and four likely pathogenic variants in COL1A1, TGFBR1/2, and SMAD3 were identified by the NGS assays. These included all previously detected single-nucleotide and other short pathogenic variants in these genes, and seven newly detected pathogenic or likely pathogenic variants leading to clinically significant diagnostic revisions. Twenty-two variants of uncertain significance were identified, seven of which were in aortopathy genes and required clinical follow-up. CONCLUSION: Unbiased NGS-based sequencing made new molecular diagnoses outside the expected EDS genotype-phenotype relationship and identified previously undetected clinically actionable variants in aortopathy susceptibility genes. These data may be of value in guiding future clinical pathways for genetic diagnosis in EDS.Genet Med 18 11, 1119-1127.

Genomic and phenotypic characterization of Vibrio cholerae non-O1 isolates from a US Gulf Coast cholera outbreak.

Between November 2010, and May 2011, eleven cases of cholera, unrelated to a concurrent outbreak on the island of Hispaniola, were recorded, and the causative agent, Vibrio cholerae serogroup O75, was traced to oysters harvested from Apalachicola Bay, Florida. From the 11 diagnosed cases, eight isolates of V. cholerae were isolated and their genomes were sequenced. Genomic analysis demonstrated the presence of a suite of mobile elements previously shown to be involved in the disease process of cholera (ctxAB, VPI-1 and -2, and a VSP-II like variant) and a phylogenomic analysis showed the isolates to be sister taxa to toxigenic V. cholerae V51 serogroup O141, a clinical strain isolated 23 years earlier. Toxigenic V. cholerae O75 has been repeatedly isolated from clinical cases in the southeastern United States and toxigenic V. cholerae O141 isolates have been isolated globally from clinical cases over several decades. Comparative genomics, phenotypic analyses, and a Caenorhabditis elegans model of infection for the isolates were conducted. This analysis coupled with isolation data of V. cholerae O75 and O141 suggests these strains may represent an underappreciated clade of cholera-causing strains responsible for significant disease burden globally.

A PPM-family protein phosphatase from the thermoacidophile Thermoplasma volcanium hydrolyzes protein-bound phosphotyrosine.

The genomes of virtually all free-living archaeons encode one or more deduced protein-serine/threonine/tyrosine kinases belonging to the so-called eukaryotic protein kinase superfamily. However, the distribution of their cognate protein-serine/threonine/phosphatases displays a mosaic pattern. Thermoplasma volcanium is unique among the Archaea inasmuch as it is the sole archaeon whose complement of deduced phosphoprotein phosphatases includes a member of the PPM-family of protein-serine/threonine phosphatases--a family that originated in the Eucarya. A recombinant version of this protein, TvnPPM, exhibited protein-tyrosine phosphatase in addition to its predicted protein-serine/threonine phosphatase activity in vitro. TvnPPM is the fourth member of the PPM-family shown to exhibit such dual-specific capability, suggesting that the ancestral versions of this enzyme exhibited broad substrate specificity. Unlike most other archaeons, the genome of T. volcanium lacks open reading frames encoding stereotypical protein-tyrosine phosphatases. Hence, the dual-specificity of TvnPPM may account for its seemingly aberrant presence in an archaeon.