Loeys-Dietz Research Articles

Endovascular repair of a dissecting pararenal abdominal aortic aneurysm in a patient with type III Loeys-Dietz syndrome

Loeys-Dietz syndrome (LDS) type 3 results from a SMAD3 mutation and is a phenotypically milder variant of LDS with frequent aortic, visceral, and cerebral vascular pathologies and osteoarthritis. Historically, endovascular treatment (endovascular aortic repair [EVAR]) of LDS-related aortic aneurysmal disease with traditional modular bifurcated devices has been limited owing to concerns regarding continued aortic dilation at proximal fixation sites. Furthermore, associated dissection pathology has also precluded traditional modular bifurcated EVAR owing to inadequate proximal infrarenal necks and narrow distal aortic domains leading to compromised contralateral gate opening and cannulation as well as limb flow compromise. To address these barriers to EVAR, we present our approach for the endovascular treatment of a dissecting pararenal abdominal aortic aneurysm using an anatomically fixated, bifurcated, unibody aortic stent graft in a patient with LDS-3.

Optimising the mutation screening strategy in Marfan syndrome and identifying genotypes with more severe aortic involvement

BackgroundMarfan syndrome (MFS) is a systemic connective tissue disorder with life-threatening manifestations affecting the ascending aorta. MFS is caused by dominant negative (DN) and haploinsufficient (HI) mutations of the FBN1 gene. Our aim was to identify mutations of MFS patients with high detection rate and to investigate the use of a gene panel for patients with Marfanoid habitus. We also aimed to examine correlations between genotype and cardiovascular manifestations to predict “malignant” mutations.Methods136 individuals were enrolled. In the first phase, next-generation sequencing (NGS) and Sanger sequencing were performed for 57 patients to screen the FBN1 gene, followed by multiplex ligation-dependent probe amplification (MLPA) in negative cases. For repeated negative results, NGS gene panel involving 9 genes was used. In the second phase, 79 patients were tested primarily with the same gene panel, negative samples were tested by MLPA.Results84 pathogenic mutations were detected, out of which 78 affected FBN1, 6 non-FBN1 mutations (2 TGFB2, 1 TGFBR2, 2 TGFBR1, 1 SMAD3) are associated with Loeys-Dietz syndrome (LDS). LDS patients had lower systemic score and they were younger, but their aortic involvement did not differ. MLPA detected 4 multi-exon deletions of FBN1 gene, which could not be identified by our first-step screening method. Aortic involvement (aortic dissection and/or dilation) did not differ significantly among HI and DN mutations (p = 0.061). Combined group of HI and DN mutations eliminating a disulphide-bonding cysteine (DN Cys) had significantly higher aortic involvement rate than DN mutations not eliminating a disulphide-bonding cysteine (DN non-Cys) (p < 0.001). Patients with DN Cys required significantly more aortic surgeries than HI and DN non-Cys mutations (p = 0.042 and p = 0.015, respectively).ConclusionsDue to the relevant number of mutations affecting genes other than FBN1, preferred approach for testing individuals with Marfanoid habitus is using a gene panel rather than single-gene analysis, followed by MLPA for negative samples. DN Cys and HI mutations should be considered as risk factors for aortic involvement. Genetic testing for patients with Marfanoid features and a systemic score under 7 is recommended, as LDS patients may have lower scores, but they may have severe cardiovascular manifestations.

Clinical Features and Outcomes of Pregnancy-Related Acute Aortic Dissection

Women with aortopathy conditions are at risk for pregnancy-related aortic dissection, and these conditions may not be recognized until after the aortic dissection occurs. To examine the clinical characteristics, imaging features, and outcomes in women with pregnancy-related acute aortic dissection. A cohort study, comprising data from the International Registry of Acute Aortic Dissection (IRAD) (February 1, 1998, to February 28, 2018). The multicenter referral center study included 29 women with aortic dissection during pregnancy or less than 12 weeks post partum in IRAD from 1998 to 2018. Clinical features of pregnancy-related aortic dissection to be studied included underlying aortopathy, aortic size, type of aortic dissection, timing of dissection, hypertension, and previous aortic surgery. A total of 29 women (mean [SD] age, 32 [6] years) had pregnancy-related aortic dissection, representing 0.3% of all aortic dissections and 1% of aortic dissection in women in the IRAD. Among women younger than 35 years, aortic dissection was related to pregnancy in 20 of 105 women (19%). Thirteen women (45%) had type A aortic dissection, and 16 women (55%) had type B. Aortic dissection onset was known in 27 women (93%): 15 during pregnancy, 4 in the first trimester, and 11 in the third trimester; 12 were post partum, occurring a mean (SD) of 12.5 (14) days post partum. At type A aortic dissection diagnosis, the mean (SD) aortic diameters were sinus of Valsalva, 54.5 (5) mm and ascending aorta, 54.7 (6) mm. At type B aortic dissection diagnosis, the mean (SD) descending aortic diameter was 32.5 (5) mm. Twenty women (69%) had an aortopathy condition or a positive family history: 13 women (65%) with Marfan syndrome, 2 women (10%) with Loeys-Dietz syndrome, 2 women (10%) with bicuspid aortic valves, 2 women (10%) with a family history of aortic disease, and 1 woman (5%) with familial thoracic aortic aneurysm. Aortopathy was not recognized until after aortic dissection in 47% of the women. Twenty-eight women (97%) survived aortic dissection hospitalization. Aortic dissection complicating pregnancy is rare. Most pregnancy-related aortic dissection is due to an aortopathy often not diagnosed until after aortic dissection. In this study, type A aortic dissections were associated with a dilated aorta, and type B aortic dissections often were not. Recognition of underlying conditions and risks for aortic dissection may improve management of pregnancy in women with aortopathy.

Anaesthetic management of a single stage surgery of anterior chest wall reconstruction and mitral valve replacement in a patient with loeys dietz syndrome

Introduction This syndrome is a rare genetic disease discovered quite recently in 2005 by Loey and colleagues 1. It is described by the syndrome of altered cardiovascular, craniofacial, neurocognitive and skeletal development caused by genetic mutations. The anaesthetic management of this patient involves that of plastic surgery and of cardiopulmonary bypass. Retrospective review of patients with LDS types 1-4 undergoing cardiovascular surgery during the years 1991-2016 showed 35 patients underwent 57 cardiac-related operations but no combined plastic and cardiothoracic case has been reported so far2. Methods This is a case report of rare and challenging anesthetic management of combined plastic surgery and cardiothoracic surgery. A 14 year old boy was referred to our centre for severe mitral regurgitation in failure planned for mitral valve replacement. He has underlying Loey's Dietz Syndrome in which he has severe pectus excavatum and thoracolumbar scoliosis. Echocardiography revealed severe mitral regurgitation, ERO 0.49cm2 and dilated annulus of 42cm. There is also mild aortic regurgitation and dilated sinus of valsalva of 42cm. The aortic annulus and sinotubular junction remained in normal range with 24mm and 28 mm respectively. Multidisplinary meeting has concluded to perform single stage surgery to avoid risk of adhesion with preservation of bilateral internal mammary artery to maintain perfusion to reconstruction site. The aortic root left untouched as it hoped by reducing volume from mitral valve replacement, the dilatation will not be worse. Results Patient underwent general anaesthesia with anterior osteomusculocutaneous chest wall island flap raised by plastic team first then proceed with cardiopulmonary bypass for mitral valve replacement (MVR). After good valvular function obtained post replacement, we proceeded with coming off bypass and anterior chest wall reconstruction by plastic team. Patient was sedated and paralysed overnight and extubated the next day. PCA fentanyl started as post-operative pain relief. Discussion The anaesthetic challenges in this case are mounting as we deal with rare congenital disease with multisystem involvement. It also combines both plastic surgery and cardiothoracic anaesthesia management with several parameters that require detailed monitoring. Further study may be required in regards to circuit priming in the case of combined cardiothoracic and plastic operation. This case however serves as a guide as to anaesthetic management in such combined procedure. Should this patient return for further cardiothoracic operation in the future, it will pose another great anaesthetic challenges.

Severity of oro-dental anomalies in Loeys-Dietz syndrome segregates by gene mutation

Background Loeys-Dietz syndrome (LDS), an autosomal dominant rare connective tissue disorder, has multisystemic manifestations, characterised by vascular tortuosity, aneurysms and craniofacial manifestations. Based on the associated gene mutations along the...

Adults with Loeys-Dietz syndrome and vascular Ehlers-Danlos syndrome: a cross-sectional study of patient experiences with physical activity

Purpose To study patient experiences with physical activity among persons with Loeys-Dietz- or vascular Ehlers-Danlos syndrome. Materials and methods A postal questionnaire survey in 2018. Seventy adults with molecularly verified Loeys-Dietz syndrome types 1-4, or vascular Ehlers-Danlos syndrome recruited through a National Resource Centre for Rare Disorders in Norway. Results The response rate was 74%, (Loeys-Dietz n = 34, vascular Ehlers-Danlos n = 18), aged 18 to 68 years, 58% women. In total, 88.5% reported they had received advice regarding physical activity and most (77%) had modified their habits. Fifty percent had an appropriate- and 40% a low mean physical activity sum score. Another 10% had too high physical activity levels due to high intensity scores. Lower scores with the Fatigue Severity Scale (p = 0.033) and the anxiety subscale of the Hospital Anxiety and Depression Scale (p = 0.021), were associated with high physical activity levels. About a third reported unmet rehabilitation needs. Conclusion Many adults with Loeys-Dietz- or vascular Ehlers-Danlos syndrome may have a potential to reach more favorable physical activity levels by increasing the frequency and duration of activities. Future directions should include evaluation of effects of professional-led practical and safe physical activity sessions as well as customized multidisciplinary rehabilitation programs for these patient groups.

A progress report on reimplantation of the aortic valve

ObjectiveTo examine the late outcomes of reimplantation of the aortic valve (RAV) in patients followed prospectively since surgery. MethodsAll 465 patients who had RAV from 1989 to 2018 were followed prospectively with periodic clinical and echocardiographic assessments. Mean follow-up was 10 ± 6 years and 98% complete. ResultsPatients' mean age was 47 ± 5.1 years, and 78% were men. The aortic root aneurysm was associated with Marfan syndrome in 164 patients, Loeys–Dietz syndrome in 13, bicuspid aortic valve (BAV) in 67, and type A aortic dissection in 33. Aortic insufficiency (AI) was greater than mild in 298 patients. Concomitant procedures were performed in 105 patients. There were 5 operative and 51 late deaths. At 20 years, 69.1% of patients were alive and free from aortic valve reoperation, and the cumulative probability of aortic valve reoperation with death as a competing risk was 6.0%, and the cumulative probability of developing moderate or severe AI was 10.2%. Only time per 1-year interval was associated with the development of postoperative AI by multivariable analysis (hazard ratio, 1.06; 95% confidence interval, >1.02-1.10; P = .006). Gradients across preserved BAV increased in 5 patients, and 1 required reoperation for aortic stenosis. Distal aortic dissections occurred in 22 patients, primarily in those with associated genetic syndromes. ConclusionsRAV provides excellent long-term results, but there is a progressive rate of AI over time, and patients with BAV may develop aortic stenosis. Patients with genetic syndromes have a risk of distal aortic dissections. Continued surveillance after RAV is necessary.

A contemporary approach to a young female patient with Loeys-Dietz syndrome and an uncomplicated type B aortic dissection: a case report

BackgroundAortic dissection is a relatively uncommon, but often catastrophic disease that requires early and accurate diagnosis. It often presents in patients with congenital connective tissue disorders. The current aortic surgical techniques are related with serious early and late complications. This case report emphasizes the importance of early diagnosis of aortic root dilatation and the risk of dissection, especially in patients with congenital connective tissue disorders. We present an alternative, contemporary and multidisciplinary approach based on the present state of knowledge.Case presentationWe present a rare case of a young female patient with Loeys-Dietz syndrome who was admitted with an uncomplicated aortic dissection (Stanford type B / DeBakey type III) and a dilated aortic root. After a period of close surveillance and extensive vascular imaging, thoracic endovascular aortic repair was deemed to be technically not possible. Medical treatment was optimized and our patient successfully underwent a personalised external aortic root support procedure (PEARS) as a contemporary alternative to existing aortic root surgical techniques.ConclusionsThis case highlights the importance of interdisciplinary approach, close follow-up and multimodality imaging. The decision to intervene in a chronic type B aortic dissection is still challenging and should be made in experienced centers by an interdisciplinary team. However, if an acute complication occurs, thoracic endovascular aortic repair TEVAR is the method of choice. In all cases optimal medical treatment is important. There is increasing evidence that personalized external aortic root support procedure PEARS is effective in stabilizing the aortic root and preventing its dilatation and dissection not only in patients with Marfan syndrome, but also in other cases of aortic root dilation of other etiologies. Moreover, many publications have reported the additional benefit of reduction or even eradication of aortic regurgitation by improving coaptation of the aortic valve leaflets in dilated aortas.

Intracranial Arterial Tortuosity in Marfan Syndrome and Loeys-Dietz Syndrome: Tortuosity Index Evaluation Is Useful in the Differential Diagnosis

The association of arterial tortuosity and connective tissue diseases is widely reported in the literature, but only a few studies were based on a quantitative evaluation of this arterial phenotype, and none of the latter examined the intracranial vasculature. The aim of this study was to evaluate the degree of intracranial arterial tortuosity in patients with Marfan syndrome and those with Loeys-Dietz syndrome, and to assess its usefulness in the differential diagnosis. We performed a retrospective analysis of 68 patients with genetically confirmed Marfan syndrome (n = 36) or Loeys-Dietz syndrome (n = 32), who underwent at least 1 MRA of the brain at our institution. Fifty-two controls were randomly selected among patients who presented with headache and without any known comorbidity. Tortuosity indexes of 4 intracranial arterial segments were measured on a 3D volume-rendered angiogram by using the following formula: [Formula: see text]. Both Marfan syndrome and Loeys-Dietz syndrome showed a significantly higher tortuosity index compared with controls in all examined vessels. The tortuosity index of the vertebrobasilar system showed an excellent interrater reliability (intraclass correlation coefficient, 0.99) and was the strongest independent predictor of Loeys-Dietz syndrome in patients with connective tissue disease (P = .002), with a 97% specificity for this pathology when its value was > 60. The tortuosity index of intracranial arteries is an easily calculated and highly reproducible measure, which shows a high specificity for Marfan syndrome and Loeys-Dietz syndrome and may be useful in differentiating these 2 entities.

The differences in surgical long-term outcomes between Marfan syndrome and Loeys-Dietz syndrome.

The aim of this study was to disclose the differences of surgical outcomes between Marfan syndrome with mutations in fibrillin-1 gene and Loeys-Dietz syndrome with mutations in transforming growth factor-beta receptor 1 and 2. We reviewed 368 patients aged less than 50years who underwent surgery for thoracic aortic diseases between 1988 and 2019, and enrolled 99 patients with Marfan syndrome (26.9%; 57 men, 33±7.5years) and 24 patients with Loeys-Dietz syndrome (6.5%; 13 men, 28±11years). Freedom from all causes of mortality was similar between the 2 groups (P=.40, log-rank). The cumulative incidence of reintervention was significantly lower in the Marfan syndrome group than in the Loeys-Dietz syndrome group (P=.016, Gray). The cumulative incidence of first aortic arch reoperation for aortic arch aneurysm was significantly lower in the Marfan syndrome group than in the Loeys-Dietz syndrome group (P<.001, Gray). The cumulative incidence of first aortic root reoperation for aortic root aneurysm (P=.57, Gray) and first descending aorta reoperation for descending aortic aneurysm (P=.76, Gray) was similar between the 2 groups. The cumulative incidence of aortic dissection after initial surgery was significantly lower in Marfan syndrome than in Loeys-Dietz syndrome (P=.0059, Gray). Loeys-Dietz syndrome with mutations in transforming growth factor-beta receptor 1 and 2 revealed higher rates of reoperation, and more specifically the arch reoperation was higher in those with Loeys-Dietz syndrome than those with Marfan syndrome. Aggressive arch surgery in the initial operation on the proximal aorta is recommendable in Loeys-Dietz syndrome to avoid additional aortic events. In Marfan syndrome, this is controversial in patients without dissection because of a low possibility to expand.

Outcomes of Thoracic Endovascular Aneurysm Repair (TEVAR) in Patients With Connective Tissue Disorders.

Thoracic endovascular aortic repair (TEVAR) remains controversial in patients with connective tissue disorders given the concern for durability. We report on the largest series to date on outcomes of patients with thoracic aortic disease and connective tissue disorders treated with TEVAR. The Vascular Quality Initiative registry identified 12 207 patients treated with TEVAR from January 2010 to December 2018, including 102 with Marfans, Ehlers-Danlos, or Loey-Dietz syndrome. Outcomes were analyzed per the Society for Vascular Surgery reporting standards. Median age was 50.6 years (interquartile range: 57.0-75.0), and 62 (60.7%) were male. Eighty-eight (86.3%) patients had Marfan, 9 (8.8%) had Ehlers-Danlos, and 5 (4.9%) had Loey-Dietz syndrome. Twenty-six (25.5%) patients were treated for degenerative aneurysmal disease and 76 (74.5%) patients for type B dissections (33 acute, 31 chronic). Most common indications for interventions in patients with type B dissection were pain (n = 41), aneurysmal degeneration (n = 16), and malperfusion (n = 8), with 3 patients who presented ruptured. There was no significant difference in perioperative complications between acute/chronic dissections and aneurysms (P = .14). Percutaneous access was utilized in 61.7% of patients, with a 2.9% rate of arterial injury requiring reintervention. Follow-up data were available for 75 (73.3%) patients at a mean follow-up of 15.6 months. Overall mortality was 5.3%. There were 30 patients with follow-up endoleak data, and 8 (26.7%) endoleaks were identified. All endoleaks were in patients treated for acute type B dissection, and all resolved after a mean of 2.1 reinterventions. Three patients treated for acute Type B Aortic Dissection (TBAD) had retrograde dissections requiring intervention. Thoracic endovascular aortic repair for patients with connective tissue disorders can be performed with low perioperative mortality, spinal cord ischemia, or Cerebrovascular Accident (CVA). On follow-up, acute type B aortic dissections represent a higher risk subgroup with increased rates of endoleak and retrograde dissection. Closer follow-up for these patients and early reintervention may be beneficial.

Hybrid Operation for a Brachiocephalic Aneurysm in a Young Woman With Loeys–Dietz Syndrome

In the currently evolving field of endovascular surgery, most brachiocephalic aneurysms are treated with stent grafts. Connective tissue disorders are considered a relative contraindication for endovascular repair because of the risk of adverse events at the landing zone in the aorta and its branches, although the surgical grafts from previous repairs could provide stable landing zones. We attempted a new hybrid operative technique for a brachiocephalic aneurysm in a patient with Loeys-Dietz syndrome, who was unsuitable for open surgery because of multiple previous surgeries and possible lung malignancy. The operation was performed by creating an appropriate landing zone using a prosthetic graft followed by endovascular stent grafting, which yielded good results. This hybrid operation is expected to expand the potential for endovascular treatment in patients with connective tissue diseases who are deemed unsuitable for open surgery.

Atlanto-axial rotary instability (Fielding type 1): characteristic clinical and radiological findings, and treatment outcomes following alignment, fusion, and stabilization

Atlanto-axial instability (AAI) is common in the connective tissue disorders, such as rheumatoid arthritis, and increasingly recognized in the heritable disorders of Stickler, Loeys-Dietz, Marfan, Morquio, and Ehlers-Danlos (EDS) syndromes, where it typically presents as a rotary subluxation due to incompetence of the alar ligament. This retrospective, IRB-approved study examines 20 subjects with Fielding type 1 rotary subluxation, characterized by anterior subluxation of the facet on one side, with a normal atlanto-dental interval. Subjects diagnosed with a heritable connective tissue disorder, and AAI had failed non-operative treatment and presented with severe headache, neck pain, and characteristic neurological findings. Subjects underwent a modified Goel-Harms posterior C1-C2 screw fixation and fusion without complication. At 15 months, two subjects underwent reoperation following a fall (one) and occipito-atlantal instability (one). Patients reported improvement in the frequency or severity of neck pain (P < 0.001), numbness in the hands and lower extremities (P = 0.001), headaches, pre-syncope, and lightheadedness (all P < 0.01), vertigo and arm weakness (both P = 0.01), and syncope, nausea, joint pain, and exercise tolerance (all P < 0.05). The diagnosis of Fielding type 1 AAI requires directed investigation with dynamic imaging. Alignment and stabilization is associated with improvement of pain, syncopal and near-syncopal episodes, sensorimotor function, and exercise tolerance.

Loeys-Dietz syndrome pathology and aspects of cardiovascular management: A systematic review.

Loeys-Dietz syndrome is an autosomal dominant genetic disorder which is associated with significant and often crucial vascular manifestations. This review is aimed to examine current evidence on pathophysiology and management of Loeys-Dietz syndrome in current era. A comprehensive electronic search was done to identify the articles that discussed all the aspects of Loeys-Dietz syndrome, combined key words and Medical Subject Headings (MeSH) terms were used. Relevant articles have been summarized in each relevant section. Loeys-Dietz syndrome is an autosomal dominant genetic disorder which has combined and multi-systemic manifestations. The increased breakdown of extracellular matrix predisposes an individual to developing aneurysms in the aortic tree which is undoubtedly the most significant complication of this disorder. Understanding the pathophysiology and natural history of Loeys-Dietz syndrome and regular surveillance is important to plan prophylactic interventions to prevent life-threatening aortic emergencies which can be fatal. Loeys-Dietz syndrome is an aggressive genetic condition that predisposes an individual to the development of life-threatening aortic aneurysms. Our understanding of Loeys-Dietz syndrome remains ever-changing and it is likely that the knowledge regarding its diagnosis and treatment will become more clearly defined in the coming years with deeper genetic studies.

Connective Tissue Abnormalities in Patients with Ruptured Intracranial Aneurysms and No Known Systemic Connective Tissue Disorder

Defect in internal elastic lamina, defect in tunica media, and the amount of collagen and elastin play a role in vessel wall weakening leading to aneurysm formation. A similar picture may be found in connective tissue disorders, such as Marfan syndrome, Ehlers-Danlos syndrome (EDS), neurofibromatosis type 1, and Loeys-Dietz syndrome (LDS), where there is a predominant disorder of collagen formation/maturation. Histopathology of skin and the superficial temporal artery (STA) was done. All specimens were obtained during craniotomy for ruptured aneurysm clipping or other indicated procedures (for control subjects). Parameters in skin biopsy seen were epithelial thickness, dermal collagen thickness, and so forth. For the STA, parameters such as intimal thickness, intimal proliferation, thickness of media, and so forth were studied. Twenty cases and twenty control subjects were studied. The mean age of the study population was 40.5 years. Salient findings on skin biopsy in patients of intracranial aneurysms (IAs) (cases) were haphazard orientation of collagen, inflammation in the subepidermal layer, increased dermal collagen thickness, and reduced and/or fragmented elastic fibers. Prominent findings on vessel wall biopsy were intimal proliferation, reduplication of internal elastic lamina, reduced and/or fragmented elastin, and vacuolation of smooth muscle cells. The average number of aberrations per patient was significantly higher in cases than control subjects. The histologic changes seen in skin and the STA in cases of IAs signify a weak connective tissue. Some of these findings are also seen in known connective tissue disorders such as Marfan syndrome, EDS, neurofibromatosis type 1, and LDS. The connective tissue abnormalities found in patients with IAs may be congenital, which gets further accentuated by known risk factors leading to weak vessel wall and subsequent aneurysm formation.

Aortopathy in Congenital Heart Disease.

Aortic dilatation is common in patients with congenital heart disease and is seen in patients with bicuspid aortic valve and those with conotruncal congenital heart defects. It is important to identify patients with bicuspid aortic valve at high risk for aortic dissection. High-risk patients include those with the aortic root phenotype and those with syndromic or familial aortopathies including Marfan syndrome, Loeys-Dietz syndrome, and Turner syndrome. Aortic dilatation is common in patients with conotruncal congenital heart defects and rarely results in aortic dissection.

Cardiovascular Risks in Patients with Loeys–Dietz Syndrome

Supplemental Digital Content is available in the text.

Orthopaedic Conditions Associated with Aneurysms.

Orthopaedic surgeons are sometimes the first specialists encountered by patients with inherited conditions that predispose them to aneurysms. The skeletal features are evident, but the aneurysm is silent. Early recognition of the conditions associated with aneurysms can lead to effective treatment and minimize risks of morbidity and death. Marfan syndrome is characterized by abnormal fibrillin-1 protein and has a broad range of skeletal manifestations, including scoliosis, hindfoot deformity, arachnodactyly, pectus excavatum or carinatum deformity, dural ectasia, and acetabular protrusio. Aneurysm-associated complications are the leading cause of early morbidity and death in patients with Marfan syndrome. Ehlers-Danlos syndrome is caused by a disturbance in collagen biosynthesis most commonly resulting in joint hypermobility and skin abnormalities. Among the types of Ehlers-Danlos syndrome, vascular Ehlers-Danlos syndrome presents the highest risk of vascular complications. Clubfoot and joint dislocations are common presenting symptoms in vascular Ehlers-Danlos syndrome. Loeys-Dietz syndrome is a connective tissue disorder resulting in aortic root dilation and several skeletal manifestations, including scoliosis, cervical malformations, joint contractures, and foot deformities.

Identification of a Pathogenic TGFBR2 Variant in a Patient With Loeys–Dietz Syndrome

Loeys–Dietz syndrome (LDS) is a rare connective tissue genetic disorder that is caused by a pathogenic variant in genes of transforming growth factor (TGF) beta receptor 1 (TGFBR1), TGFBR2, mothers against decapentaplegic homolog 2 (SMAD2), SMAD3, TGFB2, or TGFB3. It is characterized by aggressive vascular pathology, aneurysms, arterial tortuosity, bifid uvula, hypertelorism, and cleft palate. Here we present a 42-year-old female patient with LDS. The patient underwent rapidly progressing artery aneurysms and life-threatening aortic dissection. Spontaneous fracture of the first metatarsal bone was noted in her medical record. Physical examination revealed a delayed wound healing on her left abdomen. Considering these clinical manifestations, we speculated that there was a genetic defect in the connective tissue, which provides strength and flexibility to structures such as bones, skins, ligaments, and blood vessels. Thus, whole exome sequencing (WES) was performed on the proband and revealed a heterozygous missense pathogenic variant (c.1613T > C/p.Val538Ala) in TGFBR2, which was a de novo variant in the proband as confirmed by the segregation analysis in parental samples. Although this variant was discovered and associated with the phenotype of LDS previously, the pathogenicity of the variant had not been confirmed by cellular functional assay yet. To further validate the effects of the variant in vitro, we assessed the canonical TGF-β signaling pathway in mutant cells. Our results showed that the p.Val538Ala variant significantly decreased TGF-β-induced gene transcription and the phosphorylation of Smad2, which were consistent with other pathogenic variants of TGFBR2. In conclusion, this study demonstrates that the p.Val538Ala pathogenic variant in TGFBR2 leads to aberrant TGF-β signaling and LDS in this patient.

Dysregulated TGF-β Signaling Leads to Cell-Intrinsic Changes in T cell Development that Promote Allergic Inflammation

Abstract Variants in genes in the Transforming Growth Factor Beta (TGFb) signaling pathway are associated with allergic diseases suggesting that this cytokine may be a central player in allergic disease. The role of TGFb in preserving T cell mediated self-tolerance is well-appreciated but how disruption in this pathway promotes allergic inflammation is not clear. TGFb signals through its receptor TGFβRI and II, leading to phosphorylation and nuclear translocation of Smad proteins 2 and 3. We previously demonstrated that patients with Loeys-Dietz Syndrome (LDS), an autosomal dominant disorder caused by mutations in TGFBR1 and TGFBR2 are highly predisposed to developing allergic disease. Both LDS patients and mice harboring a knock-in allele (Tgfbr1mut) of an LDS mutation known to cause severe disease in humans exhibit increased levels of total and food-specific IgE, consistent with their allergic tendencies. These serologic changes were associated with increased numbers of T follicular helper (Tfh) cells which promote memory B cell and plasma cell formation, and decreased T follicular regulatory (Tfr) cells, which suppress humoral immune responses, in LDS patients and mice. Using a mixed bone marrow chimera model we demonstrated that these alterations in T cell development are cell-intrinsic. Furthermore, OVA specific OTII cells harboring the Tgfbr1mut were more likely to accumulate in the peyer’s patch, differentiate into Tfh cells, and less likely to upregulate Foxp3 in response to orally ingested OVA. Tgfbr1mut OTII cells also produced more IL-4 and less IL-10 in response to OVA. These findings suggest that TGF-β signaling plays an important role in T cell development and function that, when disrupted, promotes allergic inflammation.