[Interleukin-1 receptor associated kinase 4 deficiency: a case report and literature review].

Objective: To summarize the clinical characteristics of children with interleukin-1 receptor associated kinase 4 (IRAK4) deficiency. Methods: The clinical data of a child with IRAK4 deficiency who was admitted to the Department of Neurology of Shenzhen Children's Hospital for several times from June 2019 to August 2020 were retrospectively analyzed. Related literature up to January 2021 with the key words "IRAK4 gene variation", and "interleukin-1 receptor-associated kinase 4 deficiency" in PubMed, CNKI, Wanfang, and CQVIP databases were searched. The clinical characteristics of this disease were summarized and analyzed. Results: The boy was 6 years of age and had recurrent respiratory tract infections. He was improved after antibiotic treatment. His clinical manifestation included Streptococcus pneumoniae meningoencephalitis, multiple sclerosis, invasive discitis and inflammatory bone destruction. Family-based whole exome sequencing showed that the boy had a homozygous frameshift variation in the IRAK4 gene, NM_016123.3:C.540del (p.Phe180leufs*26), and both parents were heterozygous. A total of 23 cases were reported in ten English articles. Together with this case, there were 24 cases, including 13 males and 11 females. The age of onset was 8 days to 7 years. The main manifestations were recurrent invasive bacterial infection, including 11 cases with Streptococcus pneumoniae meningitis, 9 cases with Streptococcus pneumoniae and (or) Staphylococcus aureus septicemia, 1 case with Pseudomonas aeruginosa meningitis, 1 case of salmonella infection, and 1 case with Staphylococcus aureus skin abscess. Only 1 case had recurrent virus infection. There were 2 patients with autoimmune diseases, 1 with autoimmune encephalitis and the other one with juvenile idiopathic arthritis. Among the 24 cases, 10 died (9 in infancy). Most of the surviving children were diagnosed early and received antibiotics preventively and intravenous immunoglobulin (IVIG). Their susceptibility to infection decreased year by year, and could be close to normal children at the age of 14 years. Among the 24 cases, 21 cases had homozygous variation of IRAK4 gene and 3 cases had complex heterozygous variation. There were 15 kinds of variation, including 9 kinds of frameshift variation, 4 kinds of nonsense variation and 2 kinds of missense variation. One candidate variation hotspot was c.877 c>T (3 cases). Conclusions: IRAK4 deficiency mainly manifest as recurrent and invasive bacterial infection, with Streptococcus pneumoniae meningitis or septicemia being the most common. A few patients are complicated with autoimmune diseases. The mortality rate is high in infancy, early diagnosis and treatment can avoid severe illness or death.