1 | Introduction
Hyper-immunoglobulin
M (HIGM) syndrome is a rare (incidence: 1 in 100,000 births) primary
immunodeficiency syndrome in which defective B-cell isotype switching
leads to a phenotype characterized by low serum levels of IgG, IgA, and
IgE or their complete absence and either normal or increased
concentration of IgM. 1-4 This syndrome is known as
the immunoglobulin class-switch recombination (Ig-CSR) deficiency.
Mutations in a number of genes
involved in CSR including CD40 ligand (CD40L ), CD40 ,
nuclear factor kappa-B essential modulator, inhibitor of kappa
light-chain gene enhancer in B cells, alpha, nuclear factor kappa-B
subunit 1, and activation-induced cytidine deaminase have been
implicated in the development of HIGM. 2, 5, 6X-linked hyper-IgM (X-HIGM) syndrome, which is
caused by CD40LG mutation,
is the most common form of HIGM, accounting for approximately 65–70%
of all cases. 7, 8
Clinical manifestations of XHIGM are complex and severe. Most patients
are susceptible to opportunistic and recurrent infections that may be
accompanied by autoimmune manifestations.9 This
retrospective study on seven children diagnosed with XHIGM preliminarily
assessed the clinical presentation and pathogens of respiratory
infections in these patients and aimed to describe the respiratory
infection characteristics of these patients. We also aimed to provide
insights into the early diagnosis and target treatment strategies for
respiratory infections in these children.