Patterns of Presentation of SARS-CoV-2 Infection in Children. Experience at the Italian Epicentre of the Pandemic.

Background: COVID-19, a disease caused by the new coronavirus SARS-CoV-2, spread worldwide, and Bergamo was one of the most affected areas in Europe. Following the first outbreak, more than half of the population of the Bergamo province had been infected. We aimed to describe the patients admitted to our unit shortly after the first outbreak. Methods: we retrospectively reviewed the notes of all pediatric patients diagnosed with COVID-19. We enrolled patients with positive swabs or serology and classified them based on the pattern and the timing of presentation after the first outbreak. This setting was considered a reliable reflection of the consequences of unmitigated SARS-CoV-2 circulation. Results: We diagnosed 35 patients over a 3-month period and we identified six patterns presenting in two temporal phases: Early phase, Group 1 (median of 20 days from epidemic start, IQR: 15-27): neonatal sepsis (n.7), pneumonia (n.5), flu-like symptoms (n.2). Late phase, Group 2 (59:51-66 days, p < 0.001): MIS-C (n.18), neurological manifestations (n.3). Group 1 differed from Group 2 for younger age (1 vs. 8 years, p = 0.02), lower C-reactive protein (0.9 vs. 16.6 mg/dl, p = 0.008), procalcitonin (0.16 vs. 7.9 ng/ml, p = 0.008) and neutrophil count (3,765 vs. 6,780/µl, p = 0.006), higher rate of positive swabs (14/14 vs. 9/21, p < 0.001), higher lymphocyte count (3,000 vs. 930/µl, p = 0.006) and platelet count (323,000 vs. 210,000/µl, p = 0.009). Conclusions: Following an outbreak of unmitigated SARS-CoV-2 diffusion, infected children may present with clinical patterns suggesting two temporal clusters, the first characterized by markers of direct viral injury, the second suggesting an immune-mediated disease.

Prenatal presentation and postnatal evolution of a patient with Jansen metaphyseal dysplasia with a novel missense mutation in PTH1R.

Wave-shaped ribs were detected at prenatal ultrasound in a 20(+1) week female fetus. At birth, skeletal radiographs showed marked hypomineralization and suggested hypophosphatasia. However, elevated blood calcium and alkaline phosphatase excluded hypophosphatasia and raised the possibility of Jansen metaphyseal dysplasia. Molecular analysis of the PTH/PTHrP receptor gene (PTH1R) showed heterozygosity for a previously undescribed transversion variant (c.1373T>A), which predicts p.Ile458Lys. In vitro evaluation of wild type and mutant PTH/PTHrP receptors supported the pathogenic role of the p.Ile458Lys substitution, and confirmed the diagnosis of Jansen metaphyseal dysplasia. This disorder may present prenatally with wavy ribs and in the newborn with hypomineralization, and may therefore be confused with hypophosphatasia. The mottled metaphyseal lesions typically associated with this disease appear only in childhood.