The diagnostic value of the facial features of Marfan syndrome

Genotype-phenotype profile of global ASPH-associated ectopia lentis and clinical findings from a Chinese cohort

BACKGROUND

Traboulsi syndrome is an under-recognized syndromic form of ectopia lentis (EL) caused by the aspartate beta-Hydroxylase (ASPH) variant. The genotype-phenotype profile of ASPH-associated disease is poorly understood due to the rarity of the condition.

METHODS

We conducted targeted next-generation sequencing and bioinformatics analysis to identify potentially pathogenic ASPH variants in the cohort. Furthermore, we characterized the expression pattern of ASPH and major components of the zonules using single-cell RNA-sequencing (scRNA-seq) and evaluated the genotype-phenotype correlations by combining our data and those from the literature.

RESULTS

We identified a novel missense variant c.2075G > A (p.G692D) and a recurrent nonsense variant c.1126C > G (p.R376*) of ASPH in two pedigrees from a Chinese cohort of EL. Both probands were 5-year-old boys with canonical facial dysmorphisms and bilateral anteriorly-dislocated lenses. Other ocular comorbidities included microspherophakia, shallow anterior chamber, and narrow chamber angel. No cardiac involvements or filtering blebs were identified. The single-cell expression atlas of ciliary epithelium demonstrated the coexpression of ASPH with FBN1, FBN2, and LTBP2 in the non-pigmented ciliary epithelium cells. Furthermore, molecular modeling simulation of p.G692D revealed increased affinity to the cb EGF-like domain and a subsequent destabilized calcium-binding motif. The genotype-phenotype analysis demonstrated that patients with cardiac involvements all harbored biallelic truncation variants.

CONCLUSIONS

The data from this study provide new insights into the genotype-phenotype profile of ASPH-associated disease and implicate the potential role of ASPH in the pathogenesis of EL.

How to Distinguish Marfan Syndrome from Marfanoid Habitus in a Physical Examination-Comparison of External Features in Patients with Marfan Syndrome and Marfanoid Habitus

Marfan Syndrome (MFS) is a systemic disorder caused by mutations in fibrillin-1. The most common cause of mortality in MFS is dissection and rupture of the aorta. Due to a highly variable and age-dependent clinical spectrum, the diagnosis of MFS still remains sophisticated. The aim of the study was to determine if there exist phenotypic features that can play the role of "red flags" in cases of MFS suspicion. The study population included 306 patients (199 children and 107 adults) who were referred to the Department of Pediatric Cardiology due to suspicion of MFS. All patients underwent complete clinical evaluation in order to confirm the diagnosis of MFS according to the modified Ghent criteria. MFS was diagnosed in 109 patients and marfanoid habitus in 168 patients. The study excluded 29 patients with other hereditary thoracic aneurysm syndromes. Comparative analysis between patients with Marfan syndrome and marfanoid habitus was performed. Symptoms with high prevalence and high positive likelihood ratio were identified (pectus carinatum, reduced elbow extension, hindfoot deformity, gothic palate, downslanting palpebral fissures, lens subluxation, myopia ≥ 3 dioptres remarkably high stature). The differentiation between patients with MFS and marfanoid body habitus is not possible by only assessing external body features; however, "red flags" could be helpful in the screening phase.

Association between pectus excavatum and congenital genetic disorders: A systematic review and practical guide for the treating physician

BACKGROUND

Pectus excavatum (PE) could be part of a genetic disorder, which then has implications regarding comorbidity, the surgical correction of PE, and reproductive choices. However, referral of a patient presenting with PE for genetic analysis is often delayed because additional crucial clinical signs may be subtle or even missed in syndromic patients. We reviewed the literature to inventory known genetic disorders associated with PE and create a standardized protocol for clinical evaluation.

METHODS

A systematic literature search was performed in electronic databases. Genetic disorders were considered associated with PE if studies reported at least five cases with PE. Characteristics of each genetic disorder were extracted from the literature and the OMIM database in order to create a practical guide for the clinician.

RESULTS

After removal of duplicates from the initial search, 1632 citations remained. Eventually, we included 119 full text articles, representing 20 different genetic disorders. Relevant characteristics and important clinical signs of each genetic disorder were summarized providing a standardized protocol in the form of a scoring list. The most important clinical sign was a positive family history for PE and/or congenital heart defect.

CONCLUSIONS

Twenty unique genetic disorders have been found associated with PE. We have created a scoring list for the clinician that systematically evaluates crucial clinical signs, thereby facilitating decision making for referral to a clinical geneticist.

The Musculoskeletal Manifestations of Marfan Syndrome: Diagnosis, Impact, and Management

Purpose of Review

Marfan syndrome (MFS) is an autosomal dominant heritable disorder of fibrillin-1 (FBN1) with predominantly ocular, cardiovascular, and musculoskeletal manifestations that has a population prevalence of approximately 1 in 5–10,000 (Chiu et al. Mayo Clin Proc. 89(1):34–42, 146, Dietz 3, Loeys et al. J Med Genet. 47(7):476–85, 4).

Recent Findings

The vascular complications of MFS still pose the greatest threat, but effective management options, such as regular cardiac monitoring and elective surgical intervention, have reduced the risk of life-threatening cardiovascular events, such as aortic dissection. Although cardiovascular morbidity and mortality remains high, these improvements in cardiovascular management have extended the life expectancy of those with MFS by perhaps 30–50 years from an estimated mean of 32 years in 1972 (Dietz 3, Gott et al. Eur J Cardio-thoracic Surg. 10(3):149–58, 147, Murdoch et al. N Engl J Med. 286(15):804–8, 148). The musculoskeletal manifestations of MFS, which to date have received less attention, can also have a significant impact on the quality of life and are likely to become more important as the age of the Marfan syndrome population increases (Hasan et al. Int J Clin Pract. 61(8):1308–1320, 127). In addition, musculoskeletal manifestations are often critically important in the diagnosis of MFS.

Summary

Here, we review the main clinically relevant and diagnostically useful musculoskeletal features of MFS, which together contribute to the “systemic features score” (referred to hereafter as systemic score), part of the revised Ghent nosology for MFS. We discuss current treatment strategies and highlight the need for a multidisciplinary approach to diagnosis and management. Finally, we review new pharmacological approaches that may be disease modifying and could help to improve the outcome for individuals with this syndrome.

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.

Pseudoacromegaly

Individuals with acromegaloid physical appearance or tall stature may be referred to endocrinologists to exclude growth hormone (GH) excess. While some of these subjects could be healthy individuals with normal variants of growth or physical traits, others will have acromegaly or pituitary gigantism, which are, in general, straightforward diagnoses upon assessment of the GH/IGF-1 axis. However, some patients with physical features resembling acromegaly - usually affecting the face and extremities -, or gigantism - accelerated growth/tall stature - will have no abnormalities in the GH axis. This scenario is termed pseudoacromegaly, and its correct diagnosis can be challenging due to the rarity and variability of these conditions, as well as due to significant overlap in their characteristics. In this review we aim to provide a comprehensive overview of pseudoacromegaly conditions, highlighting their similarities and differences with acromegaly and pituitary gigantism, to aid physicians with the diagnosis of patients with pseudoacromegaly.

Truncated C-terminus of fibrillin-1 induces Marfanoid-progeroid-lipodystrophy (MPL) syndrome in rabbit

Various clinical differences have been observed between patients with the FBN1 gene mutation and those with the classical Marfan phenotype. Although FBN1 knockout (KO) or dominant-negative mutant mice are widely used as an animal model for Marfan syndrome (MFS), these mice cannot recapitulate the genotype/phenotype relationship of Marfanoid-progeroid-lipodystrophy (MPL) syndrome, which is caused by a mutation in the C-terminus of fibrillin-1, the penultimate exon of the FBN1 gene. Here, we describe the generation of a rabbit MPL model with C-terminal truncation of fibrillin-1 using a CRISPR/Cas9 system. FBN1 heterozygous (FBN1 Het) rabbits faithfully recapitulated the phenotypes of MFS, including muscle wasting and impaired connective tissue, ocular syndrome and aortic dilation. Moreover, skin symptoms, lipodystrophy, growth retardation and dysglycemia were also seen in these FBN1 Het rabbits, and have not been reported in other animal models. In conclusion, this novel rabbit model mimics the histopathological changes and functional defects of MPL syndrome, and could become a valuable model for studies of pathogenesis and drug screening for MPL syndrome.

Summary: A novel genetically engineered rabbit model of MPL syndrome, generated by CRISPR/Cas9-mediated mutation of FBN1, mimics the histopathological changes and functional defects of MPL syndrome seen in the clinic.

Oral manifestations of a rare variant of Marfan syndrome

This article reports the oral manifestations of an unusual presentation of Marfan syndrome (MFS) and provides an evidence to the importance of recognizing the oral features in confirming the diagnosis of MFS. Dentists have a vital role in confirming the diagnosis of developmental disorders that involve the craniofacial compendium.

Health supervision for children with Marfan syndrome

Marfan syndrome is a systemic, heritable connective tissue disorder that affects many different organ systems and is best managed by using a multidisciplinary approach. The guidance in this report is designed to assist the pediatrician in recognizing the features of Marfan syndrome as well as caring for the individual with this disorder.