bims-actimu 2025-03-30 papers

Issue of 2025–03–30
three papers selected by
Elodie Busch, University of Strasbourg

J Clin Immunol. 2025 Mar 28. 45(1): 85

DOCK2 Deficiency and GATA2 Haploinsufficiency Can Underlie Critical Coronavirus Disease 2019 (COVID-19) Pneumonia.

The life-threatening coronavirus disease 2019 (COVID-19) affects about 1 in 1,000 healthy people under 50 without underlying conditions. Among patients with critical COVID-19 pneumonia, rare germline variants at genes controlling type I IFN immunity have been reported in up to 5% of patients. Causal etiologies in 80-85% of cases are still unknown. We analyzed two families with hypoxemic COVID-19 pneumonia for known single-gene inborn errors of immunity. In Family 1, two siblings with critical COVID-19 were homozygous for a DOCK2 variant, c.3624+5G>A. DOCK2 deficiency is a known T-cell disorder underlying severe viral diseases. The variant resulted in skipping exon 35, which was predicted to produce a frameshift truncated protein (p.L1157Ifs*12). The proband showed markedly decreased blood CD4 T-helper cell counts, impaired T lymphocyte transformation test, and increased serum IgG, IgA, and IgE levels, as documented in other DOCK2-deficient patients. In Family 2, the proband had lethal COVID-19 and HPV-2-associated multiple recalcitrant warts. She was heterozygous for a deletion in GATA2:c.1075_1102del28, p.W360Sfs*18. GATA2 haploinsufficiency is a known cause of severe viral diseases due to a lack of plasmacytoid dendritic cell (pDC) development. The proband had monocytopenia and a lack of circulating pDCs, as reported in other patients with GATA2 haploinsufficiency. Overall, both DOCK2 deficiency and GATA2 haploinsufficiency are associated with critical and often fatal COVID-19 pneumonia.

Keywords: COVID-19; DOCK2 deficiency; GATA2 haploinsufficiency; Human papillomavirus; Inborn Errors of Immunity; Lymphocytic vasculopathy

DOI: https://doi.org/10.1007/s10875-025-01877-z

Hum Genet. 2025 Mar 26.

Congenital enteropathy caused by ezrin deficiency.

Georg F Vogel, Katharina M C Klee, Arzu Meltem Demir, Dorota Garczarczyk-Asim, Michael W Hess, Lukas A Huber, Thomas Müller, Andreas R Janecke.

Ezrin, encoded by EZR, is a central module of epithelial polarity and links membrane proteins to the actin cytoskeleton directly or indirectly through scaffold proteins in the epithelium. Ezrin knockout mice fail to thrive and do not survive past weaning. We identified a homozygous EZR loss-of-function (LoF) variant, c.356dup, by exome sequencing in an infant with intractable diarrhea and failure to thrive, who died from septicemia at 5 months of age. The variant localized within a homozygous region of 13.2 Mb in the proband, is consistent with inheritance identical-by-descent from the consanguineous parents, and segregated with disease in the proband's family. EZR transcript analyses in a heterozygous carrier showed that the variant triggers nonsense-mediated mRNA decay. Homozygous EZR LoF variants have not been reported in public databases. In this study, we generated a Caco-2 EZR knockout cell line to investigate the role of ezrin in human intestinal epithelia. Our analyses used electron and immunofluorescence microscopy to assess structural changes in the knockout cells. We observed significant disorganization of the terminal web region, microvillus rarefaction and abnormal branching. Furthermore, the absence of ezrin resulted in the mislocalization of the ezrin-interacting scaffold protein Na+/H + exchanger regulatory factor-1. In conclusion, this represents the first documentation of complete ezrin deficiency in humans, highlighting the essential and non-redundant functions of the protein in maintaining intestinal physiology.

DOI: https://doi.org/10.1007/s00439-025-02738-w

Front Pediatr. 2025 ;13 1550643

Case Report: Early diagnosis of LAD-III in newborn with persistent leukocytosis and hemangioma-like lesion of the urinary bladder.

Riccardo Pagani, Laura Lorioli, Francesca Favini, Eleonora Severi, Marco Salvi, Lidia Pezzani, Maria Iascone, Lucia Migliazza, Claudia Pellegrinelli, Maurizio Cheli, Massimo Provenzi, Giovanna Mangili.

Leukocyte Adhesion Defects (LADs) are a group of rare autosomal recessive immune disorders characterized by constitutional defects in the process of leukocyte migration. Among these, LAD-III is the rarest, with only a few cases documented in scientific literature. It is caused by mutations in the FERMT3 gene, impairing integrin function in both white blood cells and platelets. Thus, patients exhibit a variable degree of immunodeficiency along with a severe bleeding tendency referred to as "Glanzmann-like", due to dysfunctional platelet GPIIb/IIIa. The diagnosis of LAD-III is typically made in infancy or early childhood, following medical evaluations for recurrent infections and bleeding episodes. Here we report the case of a female newborn admitted to our NICU at day four of life with a history of petechial rash and gross hematuria. Radiological and endoscopic assessments revealed a hemangioma-like lesion of the bladder wall. Blood exams showed persistent leukocytosis without signs of infection, associated with mild thrombocytopenia and normocytic anemia. Notably, platelet function assays demonstrated defective aggregation with all agonists tested. Next generation sequencing analysis identified a homozygous nonsense mutation in the FERMT3 gene, ensuring early access to hematopoietic stem cell transplantation, which is the only curative treatment. To the best of our knowledge, this is the first reported case of LAD-III diagnosed in the neonatal period and the first to associate this rare disorder with bladder angiomatosis. This case highlights the importance of early genetic evaluations in newborns with unexplained hematological abnormalities and bleeding tendencies.

Keywords: FERMT3 gene; bladder hemangioma; kindlin-3; leukocyte adhesion defect type III; newborn; primary immunodeficiency

DOI: https://doi.org/10.3389/fped.2025.1550643