Currently, no reliable genotype–phenotype correlation is available for pediatric Marfan patients in everyday clinical practice. We investigated correlations of FBN1 variants with the prevalence and age of onset of Marfan manifestations in childhood and differentiated three groups: missense/in-frame, splice, and nonsense/frameshift variants. In addition, we differentiated missense variants destroying or generating a cysteine (cys-missense) and alterations not affecting cysteine. We categorized 105 FBN1-positive pediatric patients. Patients with cys-missense more frequently developed aortic dilatation (p = 0.03) requiring medication (p = 0.003), tricuspid valve prolapse (p = 0.03), and earlier onset of myopia (p = 0.02) than those with other missense variants. Missense variants correlated with a higher prevalence of ectopia lentis (p = 0.002) and earlier onset of pulmonary artery dilatation (p = 0.03) than nonsense/frameshift, and dural ectasia was more common in the latter (p = 0.005). Pectus excavatum (p = 0.007) appeared more often in patients with splice compared with missense/in-frame variants, while hernia (p = 0.04) appeared earlier in the latter. Findings on genotype–phenotype correlations in Marfan-affected children can improve interdisciplinary therapy. In patients with cys-missense variants, early medical treatment of aortic dilatation seems reasonable and early regular ophthalmologic follow-up essential. Patients with nonsense/frameshift and splice variants require early involvement of orthopedic specialists to support the growing child.

Primary cardiac tumors in children are very rare and may be associated with severe arrhythmias and sudden infant death syndrome. These cardiac arrhythmias vary depending on the location and size of the tumor. Sixty-four percent of children with cardiac fibroma, the second most common benign cardiac tumor in children, have ventricular arrhythmias, affecting therapeutic management and risk profile of these children. We report on two siblings with cardiac fibromas whose clinical presentations differed depending on their locations and size of the tumors. The first child, a three-year-old girl, was diagnosed with a cardiac fibroma in the left ventricle at the age of 8 months after surviving resuscitation due to ventricular fibrillation. Secondary prophylactic implantation of an ICD was performed. On propranolol, no further malignant arrhythmias have occurred to date. The seven-month-old brother was diagnosed postnatally with a cardiac tumor adjacent to the right ventricle. A few weeks after birth, the boy had refractory supraventricular tachycardia and ventricular arrhythmia that only resolved with amiodarone. In genetic testing, Gorlin–Goltz syndrome was diagnosed in both children. Conservative pharmacological therapy is a therapeutic strategy for asymptomatic patients with cardiac fibromas. The anti-arrhythmic medication depends on the location of the tumor. Implantation of an ICD should be performed in cases of malignant arrhythmias. In rare cases, there is an association between cardiac tumors and genetic syndromes, such as Gorlin–Goltz syndrome. These should always be considered when such a tumor is diagnosed.

OBJECTIVES: Univentricular malformations are severe cardiac lesions with limited therapeutic options and a poor long-term outcome. The staged surgical palliation (Fontan principle) results in a circulation in which venous return is conducted to the pulmonary arteries via passive laminar flow. We aimed to generate a contractile subpulmonary neo-ventricle from engineered heart tissue (EHT) to drive pulmonary flow actively. METHODS: A three-dimensional tubular EHT (1.8-cm length, 6-mm inner diameter, ca. 1-mm wall thickness) was created by casting human-induced pluripotent stem cell-derived cardiomyocytes (0.9 ml, 18 mio/ml) embedded in a fibrin-based hydrogel around a silicone tube. EHTs were cultured under continuous, pulsatile flow through the silicone tube for 23 days. RESULTS: The constructs started to beat macroscopically at days 8–14 and remained stable in size and shape over the whole culture period. Tubular EHTs showed a coherent beating pattern after 23 days in culture, and isovolumetric pressure measurements demonstrated a coherent pulsatile wave formation with an average frequency of 77 ± 5 beats/min and an average pressure of 0.2 mmHg. Histological analysis revealed cardiomyocytes mainly localized along the inner and outer curvature of the tubular wall with mainly longitudinal alignment. Cell density in the center of the tubular wall was lower. CONCLUSIONS: A simple tube-shaped contractile EHT was generated from human-induced pluripotent stem cells and developed a synchronous beating pattern. Further steps need to focus on optimizing support materials, flow rates and geometry to obtain a construct that creates sufficient pressures to support a directed and pulsatile blood flow.

Genetic factors are fundamental in the etiology of thoracic aortic aneurysm and dissection (TAAD), but the genetic cause is detected in only about 30% of cases. To define unreported TAAD-associated sequence variants, exome and gene panel sequencing was performed in 323 patients. We identified heterozygous CDKL1 variants [c.427T>C p.(Cys143Arg), c.617C>T p.(Ser206Leu), and c.404C>T p.(Thr135Met)] in 6 patients from 3 families with TAAD spectrum disorders. CDKL1 encodes a protein kinase involved in ciliary biology. Amino acid substitutions were predicted to affect CDKL1 catalytic activity or protein binding properties. CDKL1 was expressed in vascular smooth muscle cells in normal and diseased human aortic wall tissue. Cdkl1 knockdown and transient knockout in zebrafish resulted in intersomitic vessel (ISV) malformations and aortic dilation. Coinjection of human CDKL1 ^wild-type RNA, but not CDKL1 ^Cys143Arg and CDKL1 ^Ser206Leu RNA, rescued ISV malformations. All variants affected CDKL1 kinase function and profiling data, and altered protein-protein binding properties, particularly with ciliary transport molecules. Expression of CDKL1 variants in heterologous cells interfered with cilia formation and length, CDKL1 localization, and p38 MAPK and Vegf signaling. Our data suggest a role of CDKL1 variants in the pathogenesis of TAAD spectrum disorders. The association between primary cilia dysregulation and TAAD expands our knowledge of the underlying molecular pathophysiology.

BACKGROUND: Heterozygous pathogenic variants in the central region (exon 23–34) of FBN2 cause a hereditary connective tissue disorder named congenital contractural arachnodactyly, which presents with obligatory skeletal features but rarely with vascular manifestations. Scarce data exist on the association between FBN2 variants and aortic disease. This study aimed to investigate whether the location of FBN2 variants correlates with distinct clinical features, including aortic disease. METHODS: In this case-controlled cohort study, we ascertained clinical features, sequenced 62 (candidate) disease genes, and classified variants according to the American College of Medical Genetics and Genomics/Association for Molecular Pathology guidelines in 392 patients with suspected connective tissue or thoracic aortic diseases. We summarized our results and published data and compared clinical manifestations between patients with variants outside and within the central region of FBN2 . RESULTS: Heterozygous FBN2 variants outside the central region were identified in 10 patients from 5 families. Two variants were of uncertain significance, 1 was likely pathogenic, and 2 were pathogenic. A total of 60% of these patients had thoracic aortic disease, but only 20% were diagnosed with congenital contractural arachnodactyly according to an established clinical scoring system. Combined data from the literature and this study revealed that patients with FBN2 variants outside the central region presented with aortic dilatation (55.0% versus 9.9%; P <0.001) more often and had less pronounced musculoskeletal manifestations (congenital contractural arachnodactyly score, 5.6±5.1 versus 9.8±3.6; P =0.011) compared with those with central region variants. CONCLUSIONS: Our results suggest that heterozygous FBN2 variants outside the central region predispose individuals to thoracic aortic disease and are less associated with the typical clinical presentation of congenital contractural arachnodactyly than pathogenic variants in the FBN2 central region.

A 16 year-old girl with history of treated congenital mitral valve disease and signs of respiratory infection was admitted to our pediatric cardiology department. She was tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Despite her severe preexisting cardiac conditions with pulmonary hypertension, atrial arrhythmias and mitral valve stenosis, the infection did not lead to any cardiac or pulmonary deterioration. In adults, cardiac comorbidities are known risk-factors for a severe course of Covid-19 infections. This case illustrates that in children even severe cardiac disease is not necessarily associated with a severe course of Covid-19.