Exaggerated elastin turnover in young individuals with Marfan syndrome: new insights from the AIMS trial.

Aims: The fragmentation and loss of elastic fibre in the tunica media of the aorta are pathological hallmarks of Marfan syndrome (MFS) but the dynamics of elastin degradation and its relationship to aortic size and physiological growth remain poorly understood. Methods and results: In this post hoc analysis of the AIMS randomized controlled trial, the association of plasma desmosine (pDES)-a specific biomarker of mature elastin degradation-with age and aortic size was analysed in 113 patients with MFS and compared to 109 healthy controls. There was a strong association between age and pDES in both groups, with higher pDES levels in the lower age groups compared to adults. During childhood, pDES increased and peaked during early adolescence, and thereafter decreased to lower adult levels. This trend was exaggerated in young individuals with MFS but in those above 25 years of age, pDES levels were comparable to controls despite the presence of aortic root dilation. In MFS children, increased aortic diameter relative to controls was seen at an early age and although the increase in diameter was less after adolescence, aortic root size continued to increase steadily with age. In MFS participants, there was an indication of a positive association between baseline pDES levels and aortic root dilatation during up to 5 years of follow-up. Conclusion: This study has shown that developmental age has a significant effect on levels of elastin turnover as measured by pDES in MFS individuals as well as healthy controls. This effect is exaggerated in those with MFS with increased levels seen during the period of physiologic development that plateaus towards adulthood. This suggests an early onset of pathophysiology that may present an important opportunity for disease-modifying intervention.

Determining the genetic contribution in patients with non-syndromic ascending thoracic aortic aneurysms: Correlation with findings from computational pathology.

OBJECTIVES: This study aims to identify the clinical utility of targeted-genetic sequencing in a cohort of patients with TAA and establish a new method for regional histological characterisation of TAA disease. METHODS: Fifty-four patients undergoing surgery for proximal TAA were recruited. EXCLUSIONS: connective tissue disease, bicuspid aortic valves, redo surgery. All patients underwent next generation sequencing (NGS) using a custom gene panel containing 63 genes previously associated with TAA on Illumina MiSeqor NextSeq550 platforms. Explanted TAA tissue was obtained en-bloc from 34/54 patients, and complete circumferential strips of TAA tissue processed into whole slides which were subsequently digitalised. Computational pathology methods were employed to quantify elastin, cellularity and collagen in six equally divided regions across the whole aneurysm circumference. RESULTS: Of 54 patients, clearly pathogenic or potentially pathogenic variants were found in 7.4%: namely LOX, PRKG1, TGFBR1 and SMAD3 genes. 55% had at least one variant of unknown significance (VUS) and seven of the VUSs were in genes with a strong disease association (category A) genes, whilst 15 were from moderate risk (category B) genes. Elastin and collagen abundance displayed high regional variation throughout the aneurysm circumference. In patients with <60% total elastin, the loss of elastin was more significant on the outer curve (38.0% vs 47.4%, p = 0.0094). The presence of VUS, higher pulse wave velocity and advancing age were predictors of elastin loss (regression analysis: p < 0.05). CONCLUSIONS: These findings demonstrate the heterogeneity of TAA disease microstructure and the potential link between histological appearance and clinical factors, including genetic variation.

Prevalence of POC5 Coding Variants in French-Canadian and British AIS Cohort.

Adolescent idiopathic scoliosis (AIS) is a complex common disorder of multifactorial etiology defined by a deviation of the spine in three dimensions that affects approximately 2% to 4% of adolescents. Risk factors include other affected family members, suggesting a genetic component to the disease. The POC5 gene was identified as one of the first ciliary candidate genes for AIS, as three variants were identified in large families with multiple members affected with idiopathic scoliosis. To assess the prevalence of p.(A429V), p.(A446T), and p.(A455P) POC5 variants in patients with AIS, we used next-generation sequencing in our cohort of French-Canadian and British families and sporadic cases. Our study highlighted a prevalence of 13% for POC5 variants, 7.5% for p.(A429V), and 6.4% for p.(A446T). These results suggest a higher prevalence of the aforementioned POC5 coding variants in patients with AIS compared to the general population.

Genetic variant of TTLL11 gene and subsequent ciliary defects are associated with idiopathic scoliosis in a 5-generation UK family.

Idiopathic scoliosis (IS) is a complex 3D deformation of the spine with a strong genetic component, most commonly found in adolescent girls. Adolescent idiopathic scoliosis (AIS) affects around 3% of the general population. In a 5-generation UK family, linkage analysis identified the locus 9q31.2-q34.2 as a candidate region for AIS; however, the causative gene remained unidentified. Here, using exome sequencing we identified a rare insertion c.1569_1570insTT in the tubulin tyrosine ligase like gene, member 11 (TTLL11) within that locus, as the IS causative gene in this British family. Two other TTLL11 mutations were also identified in two additional AIS cases in the same cohort. Analyses of primary cells of individuals carrying the c.1569_1570insTT (NM_194252) mutation reveal a defect at the primary cilia level, which is less present, smaller and less polyglutamylated compared to control. Further, in a zebrafish, the knock down of ttll11, and the mutated ttll11 confirmed its role in spine development and ciliary function in the fish retina. These findings provide evidence that mutations in TTLL11, a ciliary gene, contribute to the pathogenesis of IS.

Marfan syndrome and the eye clinic: from diagnosis to management.

Marfan syndrome (MFS) is an autosomal dominantly inherited disorder affecting the cardiovascular, ocular and musculoskeletal systems. Frequently, clinical suspicion and subsequent diagnosis begins in the ophthalmology clinic. Importantly, the ophthalmologist has a responsibility to cater not only to the eye, but also to be involved in a holistic approach for these patients. In this review, we discuss how MFS may present to an eye clinic, including clinical features, ocular morbidity, genetic diagnosis and management. Although this condition is ideally managed by a multidisciplinary team, our focus will be on MFS and the eye, including other conditions which may present with similar phenotypes. The ophthalmologist's role as the potential first contact for a patient with suspected MFS is crucial in making the proper investigations and referral, with the knowledge that not all ectopia lentis cases are MFS and vice versa. Management of ocular conditions in MFS may range from simple observation to surgical intervention; current options will be discussed.

Eye problems in Marfan Syndrome ­ A Review Marfan syndrome (MFS) is an inherited disorder that affects many systems of the body, including the heart, joints, skeleton, skin and eyes. Although the more dangerous problems caused by this are to do with the heart and blood vessels, it is quite often that such patients are first found by eye doctors. They are either seen due to being very short-sighted or with dislocated lenses which can cause major problems in the eye. Eye problems can be managed by regular observation, although they often require surgery. Because eye doctors are often the first to see these patients, they must involve other doctors of different specialities to help in diagnosing and managing important issues these patients may have, especially affecting the heart and major blood vessels. Confirmation of diagnosis is done through genetic testing, which has advanced greatly, finding new mutations which may contribute to this disorder. Genetic counselling services can help families in understanding their diagnosis and making better informed decisions about future family planning as well as screening other family members. The eye is just one part of this complex genetic disease. We look in detail at how eye doctors can best approach such patients.

Irbesartan in Marfan syndrome (AIMS): a double-blind, placebo-controlled randomised trial.

BACKGROUND: Irbesartan, a long acting selective angiotensin-1 receptor inhibitor, in Marfan syndrome might reduce aortic dilatation, which is associated with dissection and rupture. We aimed to determine the effects of irbesartan on the rate of aortic dilatation in children and adults with Marfan syndrome. METHODS: We did a placebo-controlled, double-blind randomised trial at 22 centres in the UK. Individuals aged 6-40 years with clinically confirmed Marfan syndrome were eligible for inclusion. Study participants were all given 75 mg open label irbesartan once daily, then randomly assigned to 150 mg of irbesartan (increased to 300 mg as tolerated) or matching placebo. Aortic diameter was measured by echocardiography at baseline and then annually. All images were analysed by a core laboratory blinded to treatment allocation. The primary endpoint was the rate of aortic root dilatation. This trial is registered with ISRCTN, number ISRCTN90011794. FINDINGS: Between March 14, 2012, and May 1, 2015, 192 participants were recruited and randomly assigned to irbesartan (n=104) or placebo (n=88), and all were followed for up to 5 years. Median age at recruitment was 18 years (IQR 12-28), 99 (52%) were female, mean blood pressure was 110/65 mm Hg (SDs 16 and 12), and 108 (56%) were taking ß blockers. Mean baseline aortic root diameter was 34·4 mm in the irbesartan group (SD 5·8) and placebo group (5·5). The mean rate of aortic root dilatation was 0·53 mm per year (95% CI 0·39 to 0·67) in the irbesartan group compared with 0·74 mm per year (0·60 to 0·89) in the placebo group, with a difference in means of -0·22 mm per year (-0·41 to -0·02, p=0·030). The rate of change in aortic Z score was also reduced by irbesartan (difference in means -0·10 per year, 95% CI -0·19 to -0·01, p=0·035). Irbesartan was well tolerated with no observed differences in rates of serious adverse events. INTERPRETATION: Irbesartan is associated with a reduction in the rate of aortic dilatation in children and young adults with Marfan syndrome and could reduce the incidence of aortic complications. FUNDING: British Heart Foundation, the UK Marfan Trust, the UK Marfan Association.

Cardiovascular Management of Adults with Marfan Syndrome.

Marfan syndrome (MFS) is a disease in which connective tissue becomes weak secondary to fibrillin-1 mutations, resulting in aortic dilatation, aneurysm formation, aortic dissection, aortic regurgitation and mitral valve prolapse. This autosomal dominantly inherited condition, which was first reported in 1895 and was more fully described in 1931, is characterised by abnormal Fibrillin-1 protein (FBN1) (discovered in 1990), which is encoded by the FBN1 gene (reported in 1991). In the 1970s, the life expectancy of people with MFS was 40-50 years, mainly due to increased risk of aortic dissection or heart failure from aortic or mitral regurgitation. However, due to advances in medical and surgical therapy, life expectancy has improved dramatically and is now comparable to that of the general population. We discuss the cardiac manifestations of MFS, the incidence of arrhythmia in this population, the standard of medical care for arrhythmia and valve insufficiency, and a new use of preventive medication to preserve the integrity of the aortic wall in patients with MFS.

Craniosynostosis with ectopia lentis and a homozygous 20-base deletion in ADAMTSL4.

Craniosynostosis with ectopia lentis has been described five times since 1950 with unknown inheritance and variable phenotype. The patient was diagnosed with right coronal synostosis at age 10 weeks requiring surgery, and bilateral ectopia lentis with high myopia at 10 months. No other family member was affected. There is no known consanguinity within the family. Genetic screening ruled out FBN1, TGFBR2, and the known craniosynostosis hotspots (FGFR2 exon 8 and exon 10 and FGFR3 exon 6) as the cause. A homozygous deletion in exon 6 of ADAMTSL4 (c.767_786del 20) that has been shown to cause isolated ectopia lentis was found. The mutation results in a premature termination codon (p.Gln256ProfsX38). The proband's mother, father and one sibling are heterozygous carriers of the mutation. This is the first detailed report of a possible genetic determinant of craniosynostosis with ectopia lentis. Although this mutation causes isolated ectopia lentis, this may be evidence of pleiotropic effects of ADAMTSL4 and may represent an overlapping syndrome with a causative mutation in ADAMTSL4. These findings need to be confirmed in further cases with craniosynostosis and ectopia lentis.

Role of ADAMTSL4 mutations in FBN1 mutation-negative ectopia lentis patients.

Ectopia lentis (EL) is genetically heterogeneous with both autosomal-dominant and -recessive forms. The dominant disorder can be caused by mutations in FBN1, at the milder end of the type-1 fibrillinopathies spectrum. Recently in a consanguineous Jordanian family, recessive EL was mapped to locus 1q21 containing the ADAMTSL4 gene and a nonsense mutation was found in exon 11 (c.1785T>G, p.Y595X). In this study, 36 consecutive probands with EL who did not fulfill the Ghent criteria for MFS were screened for mutations in FBN1 and ADAMTSL4. Causative FBN1 mutations were identified in 23/36 (64%) of probands while homozygous or compound heterozygous ADAMTSL4 mutations were identified in 6/12 (50%) of the remaining probands. Where available, familial screening of these families confirmed the mutation co-segregated with the EL phenotype. This study confirms that homozygous mutations in ADAMTSL4 are associated with autosomal-recessive EL in British families. Furthermore; the first compound heterozygous mutation is described resulting in a PTC and a missense mutation in the PLAC (protease and lacunin) domain. The identification of a causative mutation in ADAMTSL4 may allow the exclusion of Marfan syndrome in these families and guide the clinical management, of particular relevance in young children affected by EL.