Claus, Laura R.

Background Adolescents with chronic disease are often exposed to inflammatory, metabolic, and hemodynamic risk factors for early atherosclerosis. Since postmortem studies have shown that atherogenesis starts in the aorta, the CDACD (Cardiovascular Disease in Adolescents with Chronic Disease) study investigated preclinical aortic atherosclerosis in these adolescents. Methods and Results The cross‐sectional CDACD study enrolled 114 adolescents 12 to 18 years old with chronic disorders including juvenile idiopathic arthritis, cystic fibrosis, obesity, corrected coarctation of the aorta, and healthy controls with a corrected atrial septal defect. Cardiovascular magnetic resonance was used to assess aortic pulse wave velocity and aortic wall thickness, as established aortic measures of preclinical atherosclerosis. Cardiovascular magnetic resonance showed a higher aortic pulse wave velocity, which reflects aortic stiffness, and higher aortic wall thickness in all adolescent chronic disease groups, compared with controls ( P <0.05). Age (β=0.253), heart rate (β=0.236), systolic blood pressure (β=−0.264), and diastolic blood pressure (β=0.365) were identified as significant predictors for aortic pulse wave velocity, using multivariable linear regression analysis. Aortic wall thickness was predicted by body mass index (β=0.248) and fasting glucose (β=0.242), next to aortic lumen area (β=0.340). Carotid intima‐media thickness was assessed using ultrasonography, and was only higher in adolescents with coarctation of the aorta, compared with controls ( P <0.001). Conclusions Adolescents with chronic disease showed enhanced aortic stiffness and wall thickness compared with controls. The enhanced aortic pulse wave velocity and aortic wall thickness in adolescents with chronic disease could indicate accelerated atherogenesis. Our findings underscore the importance of the aorta for assessment of early atherosclerosis, and the need for tailored cardiovascular follow‐up of children with chronic disease.

Abstract BACKGROUND AND AIMS NEK8/NPHP9 encodes a protein that localizes to the primary cilium. Biallelic NEK8 variants are known to cause multiorgan developmental defects, including kidney cystic dysplasia and extensive extra-renal defects, with heterozygous carrier parents being asymptomatic [1]. This autosomal recessive inheritance is the most common inheritance mode for ciliopathies. Complementary to this, we now propose a dominant negative effect for specific heterozygous NEK8 missense variants in the kinase domain resulting in an autosomal-dominant ciliopathy. METHOD We performed genetic testing in patients from several medical centers. To explore the consequences of the identified NEK8 variants, we are performing cilia staining assays in patients' skin fibroblast and kidney cells, as well as in mIMCD3 cells overexpressing the identified variants. Furthermore, we are examining the impact of the NEK8 variants on replication stress response. RESULTS We identified three distinct heterozygous NEK8 variants in 12 families (Table 1), all leading to missense alterations in the kinase domain. Interestingly the p.Arg45Trp variant is a recurrent variant we detected in 10 unrelated families. All patients have a kidney phenotype that varies from mild focal segmental glomerulosclerosis to prenatal presentation with polycystic kidneys. Most patients have kidney failure needing kidney replacement therapy at varying ages of onset. In all patients, we thoroughly checked whether a second variant could be found. Furthermore, the large symptomatic family and de novo occurrences favor a dominant inheritance mode. Our preliminary results from functional studies show abnormal primary cilia formation in serum-starved cells as well as increased replication stress. CONCLUSION We present the first evidence for a pathogenic effect of heterozygous NEK8 variants. Remarkably our patients present with a kidney limited phenotype as compared to the multiorgan defects found in patients with biallelic variants. This reveals a new mode of inheritance for NEK8 variants and expands genotype-phenotype correlations for this gene.