IgG4-RD is a systemic inflammatory and sclerosing disease. Parotid and lacrimal involvement (formerly called Mikulicz's disease), lymphadenopathy and pancreatitis are the most common manifestations. Patients with IgG4-RD showed favourable responses to treatment with glucocorticoids and immunosuppressive agents.

What's already known about this topic? Confined placental mosaicism (CPM) is a known biological phenomenon that can lead to false positive non-invasive prenatal test results. The small number of false negative non‐invasive prenatal test results reported to date are believed to be because of a low fetal DNA fraction in maternal plasma and/or placental mosaicism What does this study add? The degree and compartmentalization of placental mosaicism can potentially reduce the effective output of fetal DNA into the maternal circulation to steady state levels below the detection limit of non‐invasive prenatal testing, leading to a false negative result

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