Genetic profiling and cardiovascular phenotypic spectrum in a Chinese cohort of Loeys-Dietz syndrome patients

A systematic review supporting the Society for Vascular Surgery guidelines on the management of heritable aortopathies

BACKGROUND

To support the development of clinical practice guidelines on the management of patients with genetic aortopathies and arteriopathies, a writing committee from the Society for Vascular Surgery has commissioned this systematic review.

METHODS

We conducted a systematic review and searched multiple databases for studies addressing six questions identified by the Society for Vascular Surgery guideline committee about evaluating and managing patients with genetic aortopathies and arteriopathies. Studies were selected and appraised by pairs of independent reviewers.

RESULTS

We included 12 studies in this systematic review. We did not identify studies about the long-term outcomes of endovascular repair for aortic aneurysm in patients with heritable aortopathy or about new aortic events in pregnant women with a history of aortic dissection (AD) or aneurysm. A small case series demonstrated a 100% survival rate and 100% aortic intervention-free survival at 15 months (range, 7-28 months) after endograft repair for type B AD. A positive genetic diagnosis was discovered in 36% of patients with aortic aneurysms and dissections who had no risk factors for hereditary aortopathies, and these patients had a mortality rate of 11% at a median follow-up duration of 5 months. Black patients had lower 30-day mortality than White patients (5.6% vs 9.0%, respectively), but they had a higher overall aortic reintervention rate at 30 days after AD repair (47% vs 27%, respectively). Aortic reinterventions owing to aneurysmal expansion and endoleak at 30 days were higher in Black patients than White patients. The certainty of evidence was judged to be very low across all the outcomes evaluated in this systematic review.

CONCLUSIONS

The available evidence suggests high survival after thoracic endovascular aortic repair for type B AD in young patients with heritable aortopathies, but with limited long-term follow-up. Genetic testing in patients with acute aortic aneurysms and dissections had a high yield. It was positive for most patients with risk factors for hereditary aortopathies and in more than one-third for all other patients, and was associated with new aortic events within 15 years.

A systematic study of mosaicism in heritable thoracic aortic aneurysm and dissection

Mosaicisms are often overlooked in routine molecular diagnosis. Although not common, they are of great significance for accurate diagnosis and genetic counseling. In this study, we systematically evaluated the frequency of mosaicisms in both asymptomatic parents and affected patients with thoracic aortic aneurysm and dissection (TAAD). Next-generation sequencing (NGS) data from 1085 patients was reanalyzed with a more lenient allele frequency to detect potential mosaic variants. In addition, parental mosaicisms were investigated in 80 TAAD families. Finally, a total of six mosaic variants were detected in our cohort. Three of them were identified in symptomatic patients and three were in asymptomatic parents. Notably, a low-level mosaic variant in TGFB2 was detected combined with a causative FBN1 variant in patient AD2001, which might partially explain the clinical heterogeneity in his family. Our study hinted that it is necessary and feasible to implement mosaicism analysis in routine molecular diagnosis.

Familial exudative vitreoretinopathy with TGFBR2 mutation without signs of Loeys-Dietz syndrome

Background: Familial exudative vitreoretinopathy (FEVR) is an inherited retinal disorder with high genetic heterogeneity, and it is characterized by a defect in the development of the retinal vascular system. Loeys-Dietz syndrome (LDS) is an autosomal dominant systemic connective tissue disorder that is caused by mutations in the genes related to transforming growth factor signaling systems including the TGFBR2 gene. Two earlier studies reported that patients with LDS from mutations in the TGFBR2 gene were associated with FEVR-like retinal phenotype. The purpose of this study was to determine the characteristics of a case of FEVR without systemic abnormalities who had a mutation in the TGFBR2 gene.Materials and Methods: The clinical appearances and surgical outcomes were determined from the medical records. Genetic analysis was performed by whole exome sequencing.Results: A 15-year-old boy was diagnosed with FEVR by the appearance of the peripheral retina of both eyes and a retinal detachment in the left eye. Whole exome sequencing revealed a heterozygous deletion mutation in the TGFBR2 gene. A de novo mutation was confirmed by examining the family members. No systemic abnormalities were detected in the patient including those associated with LDS.Conclusions: FEVR can be associated with a TGFBR2 mutation without showing signs of LDS.

Loeys-Dietz syndrome associated with a heterozygous mutation in TGFBR2 in a female infant: A case report

Loeys-Dietz syndrome (LDS) is an unusual hereditary connective tissue disease with no clear standard clinical diagnosis. The present report describes a case of an infant diagnosed with LDS at the age of 2 months and 23 days. To the best of our knowledge, this case represents the youngest reported case of LDS in China. Whole exome sequencing revealed a heterozygous variation, c.1441(exon 6)G>A [p.E481k(p.Glu481Lys) (NM_001024847)], located at chr3:30715708 in the transforming growth factor β receptor 2 gene. The patient underwent systematic rehabilitation and standard high-risk infant follow-up. Currently, the overall development of the patient continues to improve. The patient can walk with assistance, stand up on her feet unaided, exhibits improved optical line of sight and both eyes can move up and down, side to side (left and right) and track moving objects. The parents have been advised that a further echocardiogram should be performed as soon as possible and regular follow-up sessions with a cardiovascular specialist are ongoing. LDS diagnosis was confirmed in the patient based on collective findings of skeletal system changes, ocular hypertelorism, ocular exotropia, micrognathia and high-vaulted palate, in combination with a specific pathogenic gene mutation.