• Haruka Tokutake and Satoko Chiba.
• Department of Pediatrics, Hirosaki General Medical Center.
• Tohoku J. Exp. Med. 2022 Aug 3; 257 (4): 347-352.

AbstractThe 8p inverted duplication deletion [inv dup del(8p)] is a complex structural rearrangement in chromosome 8. Patients with this chromosomal abnormality exhibit developmental delay, facial dysmorphism, central nervous abnormalities, hypotonia, orthopedic abnormalities, and congenital heart defects. However, cellular immune function in inv dup del(8p) syndrome has never been reported. We present the case of a 1-month-old boy with inv dup del(8p) syndrome who had severe respiratory syncytial (RS) virus bronchiolitis. Natural killer (NK) cells are recruited to airway epithelium in the early phase of RS viral infection. A cluster of defensin genes (DEFs), which are deleted in inv dup del(8p), are located in 8p23.1. Human defensins are involved in antiviral activity through the NK cell-mediated cytotoxic pathway and envelope disruption in the normal immune response. This patient showed lower NK cell activity and α-defensin level compared with healthy controls. These results suggest that decreased NK cell activity can result from DEF haploinsufficiency. In addition to a skeletal deformity with chromosomal abnormality, NK cell-mediated immune deficiency may account for the exacerbation of RS virus bronchiolitis.

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