A Cohort Study on Deficiency of ADA2 from China.

PURPOSE: Deficiency of adenosine deaminase 2 (DADA2), an autosomal recessive autoinflammatory disorder caused by biallelic loss-of-function variants in adenosine deaminase 2 (ADA2), has not been systemically investigated in Chinese population yet. We aim to further characterize DADA2 cases in China. METHODS: A retrospective analysis of patients with DADA2 identified through whole exome sequencing (WES) at seventeen rheumatology centers across China was conducted. Clinical characteristics, laboratory findings, genotype, and treatment response were analyzed. RESULTS: Thirty patients with DADA2 were enrolled between January 2015 and December 2021. Adenosine deaminase 2 enzymatic activity was low in all tested cases to confirm pathogenicity. Median age of disease presentation was 4.3 years and the median age at diagnosis was 7.8 years. All but one patient presented during childhood and two subjects died from complications of their disease. The patients most commonly presented with systemic inflammation (92.9%), vasculitis (86.7%), and hypogammaglobinemia (73.3%) while one patient presented with bone marrow failure (BMF) with variable cytopenia. Twenty-three (76.7%) patients were treated with TNF inhibitors (TNFi), while two (6.7%) underwent hematopoietic stem cell transplantation (HSCT). They all achieved clinical remission. A total of thirty-nine ADA2 causative variants were identified, six of which were novel. CONCLUSION: To establish early diagnosis and improve clinical outcomes, genetic screening and/or testing of ADA2 enzymatic activity should be performed in patients with suspected clinical features. TNFi is considered as first line treatment for those with vascular phenotypes. HSCT may be beneficial for those with hematological disease or in those who are refractory to TNFi.

[Clinical features of children with periodic fever, aphthous stomatitis, pharyngitis, and adenitis syndrome: an analysis of 13 cases].

OBJECTIVE: To study the clinical features of children with periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome, a polygenic and multifactorial autoinflammatory disease with unknown pathogenesis. METHODS: A retrospective analysis was performed on the medical data of 13 children with PFAPA syndrome. RESULTS: All 13 children had disease onset within the age of 3 years, with a mean age of onset of (14±10) months. They all had periodic fever, with 8-18 attacks each year. The mean interictal period of fever was (30±5) days. Pharyngitis, cervical adenitis, and aphthous stomatitis were the three cardinal symptoms, with incidence rates of 100% (13/13), 85% (11/13), and 38% (5/13) respectively. There were increases in white blood cells, C-reactive protein, and erythrocyte sedimentation rate during fever. Of all the 13 children, 6 underwent whole exome sequencing and 7 underwent panel gene detection for autoinflammatory disease, and the results showed single heterozygous mutations in the MEFV gene in 6 children (46%). Recurrent fever in all children gradually returned to normal without antibiotics. Ten children were treated with a single dose of glucocorticoids, and fever was relieved after treatment. Of all the children, 4 were treated with cimetidine, among whom 2 had response; 4 children were treated with colchicine, among whom 2 had response and 2 were withdrawn from the drug due to adverse reactions. Tonsillectomy was performed for 2 children, among whom 1 was followed up for 3 years without recurrence and 1 still had recurrence. CONCLUSIONS: For children with unexplained periodic fever with early onset accompanied by pharyngitis, cervical adenitis, aphthous stomatitis, elevated inflammatory indices, and good response to glucocorticoids, PFAPA syndrome should be considered. This disorder has good prognosis, and early diagnosis can avoid the long-term repeated use of antibiotics.