A +3 variant at a donor splice site leads to a skipping of the MYH11 exon 32, a recurrent RNA defect causing Heritable Thoracic Aortic Aneurysm and Dissection and/or Patent Ductus Arteriosus.

BACKGROUND: Pathogenic variants in MYH11 are associated with either heritable thoracic aortic aneurysm and dissection (HTAAD), patent ductus arteriosus (PDA) syndrome, or megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS). METHODS AND RESULTS: We report a family referred for molecular diagnosis with HTAAD/PDA phenotype in which we found a variant at a non-conserved position of the 5' donor splice site of intron 32 of MYH11 potentially altering splicing (NM_002474.3:c.4578+3A>C). Although its cosegregation with disease was observed, it remained of unknown significance. Later, aortic surgery in the proband gave us the opportunity to perform a transcript analysis. This showed a skipping of the exon 32, an RNA defect previously reported to be translated to an in-frame loss of 71 amino acids and a dominant-negative effect in the smooth muscle myosin rod. This RNA defect is also reported in 3 other HTAAD/PDA pedigrees. CONCLUSION: This report confirms that among rare variants in MYH11, skipping of exon 32 is recurrent. This finding is of particular interest to establish complex genotype-phenotype correlations where some alleles are associated with autosomal dominant HTAAD/PDA, while others result in recessive or dominant visceral myopathies.

Incidence of cardiovascular events and risk markers in a prospective study of children diagnosed with Marfan syndrome.

BACKGROUND: Little is known about the incidence of cardiovascular events (CVEs) and their associated risk markers in children with Marfan syndrome (MFS). AIMS: To assess the incidence of CVEs and determine risk markers in a cohort diagnosed with Marfan syndrome during childhood and followed for several years. METHODS: From a French multicentre nationwide database, 462 patients with MFS diagnosed during childhood were included prospectively. Patients' files were screened for a period of 20 years (1993-2013). CVEs (e.g. death, aortic dissection, cardiac valve or aortic root surgery) were assessed during the prospective follow-up. RESULTS: Median (interquartile range) age at the end of follow-up was 17.2 (11.1-21.3) years. CVEs were reported for 35 participants (7.6%; 95% confidence interval [CI] 5.3-10.4%). First CVEs were prophylactic aortic root surgery (n=29), aortic dissection (n=4; two aged <18 years) and death (n=2). Kaplan-Meier cumulative incidence of CVEs was 5.3% (95% CI 3.3-8.7%) during childhood (aged≤18 years) and 19.4% (95% CI 13.3-27.9%) at 25years of age. The cumulative rate of CVEs was higher in case of Valsalva sinus Z-score increase of≥0.1 per year (P=0.0003), maximal Valsalva sinus diameter growth speed ≥5mm per year (P=0.03), aortic regurgitation≥2 (P=0.0005) and maximal Valsalva sinus Z-score≥3 before 16 years of age (P<0.0001). In a multivariable Cox proportional analysis, the Valsalva sinus Z-score remained significantly related to outcome. Considering aortic root evolution, aortic regurgitation, age at diagnosis and beta-blocker therapy were related to Valsalva sinus Z-score evolution during follow-up. CONCLUSIONS: CVEs in children with MFS are mainly related to prophylactic aortic root surgery. Aortic dissections are rarely observed in children. The Valsalva sinus Z-score is a strong indicator of subsequent CVEs in children with MFS. Attention to follow-up and beta-blocker observance may be warranted in high-risk children.

Constitutional chromoanasynthesis: description of a rare chromosomal event in a patient.

Structural alterations in chromosomes are a frequent cause of cancers and congenital diseases. Recently, the phenomenon of chromosome crisis, consisting of a set of tens to hundreds of clustered genomic rearrangements, localized in one or a few chromosomes, was described in cancer cells under the term chromothripsis. Better knowledge and recognition of this catastrophic chromosome event has brought to light two distinct entities, chromothripsis and chromoanasynthesis. The complexity of these rearrangements and the original descriptions in tumor cells initially led to the thought that it was an acquired anomaly. In fact, a few patients have been reported with constitutional chromothripsis or chromoanasynthesis. Using microarray we identified a very complex chromosomal rearrangement in a patient who had a cytogenetically visible rearrangement of chromosome 18. The rearrangement contained more than 15 breakpoints localized on a single chromosome. Our patient displayed intellectual disability, behavioral troubles and craniofacial dysmorphism. Interestingly, the succession of duplications and triplications identified in our patient was not clustered on a single chromosomal region but spread over the entire chromosome 18. In the light of this new spectrum of chromosomal rearrangements, this report outlines the main features of these catastrophic events and discusses the underlying mechanism of the complex chromosomal rearrangement identified in our patient, which is strongly evocative of a chromoanasynthesis.

Mutations in WNT10A are frequently involved in oligodontia associated with minor signs of ectodermal dysplasia.

Ectodermal dysplasias (ED) are a clinically and genetically heterogeneous group of hereditary disorders that have in common abnormal development of ectodermal derivatives. Hypohidrotic ectodermal dysplasia (HED) is characterized by abnormal development of eccrine sweat glands, hair, and teeth. The X-linked form of the disease, caused by mutations in the EDA gene, represents the majority of patients with the hypohidrotic form. Autosomal dominant and autosomal recessive forms are occasionally seen, and result from mutations in at least three genes (WNT10A, EDAR, or more rarely EDARADD). We have screened for mutations in EDAR (commonly involved in the hypohidrotic form) and WNT10A (involved in a wide spectrum of ED and in isolated hypodontia) in a cohort of 36 patients referred for EDA molecular screening, which failed to identify any mutation. We identified eight EDAR mutations in five patients (two with homozygous mutations, one with compound heterozygous mutations, and two with heterozygous mutation), four of which were novel variants. We identified 28 WNT10A mutations in 16 patients (5 with homozygous mutations, 7 with compound heterozygous mutations, and 4 with heterozygous mutations), seven of which were novel variants. Our study allows a more precise definition of the phenotypic spectrum associated with EDAR and WNT10A mutations and underlines the importance of the implication of WNT10A among patients with ED.