Affiliations 

  • 1 Primary Immunodeficiency Unit, Allergy and Immunology Research Centre, Institute for Medical Research, National Institutes of Health, Ministry of Health, Selangor, Malaysia
  • 2 Pediatric Department, Penang General Hospital, Ministry of Health, Penang, Malaysia
  • 3 Medical Mycology Laboratory, Infectious Diseases Research Centre, Institute for Medical Research, National Institutes of Health, Ministry of Health, Selangor, Malaysia
  • 4 Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
  • 5 Primary Immunodeficiency Unit, Allergy and Immunology Research Centre, Institute for Medical Research, National Institutes of Health, Ministry of Health, Selangor, Malaysia. adiratna@moh.gov.my
J Clin Immunol, 2021 08;41(6):1178-1186.
PMID: 33713249 DOI: 10.1007/s10875-021-01017-3

Abstract

X-linked agammaglobulinemia is a rare primary immunodeficiency due to a BTK mutation. The patients are characteristically deficient in peripheral B cells and serum immunoglobulins. While they are susceptible to infections caused by bacteria, enteroviruses, and parasites, fungal infections are uncommon in XLA patients. Here, we report a boy of Malay ethnicity who suffered from recurrent upper respiratory tract infections and severe progressive necrotizing fasciitis caused by Saksenaea erythrospora. Immunological tests showed a B cell deficiency and hypogammaglobulinemia. Whole-exome sequencing identified a dinucleotide deletion (c.1580_1581del) in BTK, confirmed by Sanger sequencing and predicted to be disease causing by in silico functional prediction tools (Varsome and MutationTaster2) but was absent in the gnomAD database. This mutation resulted in a frameshift and premature termination (p.C527fs), which disrupted the protein structure. The mother was heterozygous at the mutation site, confirming her carrier status. Flow cytometric analysis of monocyte BTK expression showed it to be absent in the patient and bimodal in the mother. This study describes a novel BTK mutation in a defined hotspot and an atypical fungal phenotype in XLA. Further studies are required to understand the pathogenesis of fungal infection in XLA.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.