Search

Background DNA Ligase IV (LIG4) syndrome is a rare disease with few reports to date. Patients suffer from a broad spectrum of clinical features, including microcephaly, growth retardation, developmental delay, dysmorphic facial features, combined immunodeficiency, and malignancy predisposition. There may be a potential association between genotypes and phenotypes. We investigated the characteristics of LIG4 syndrome in a Chinese cohort. Results All seven patients had growth restriction. Most patients (6/7) had significant microcephaly (< − 3 SD). Recurrent bacterial infections of the lungs and intestines were the most common symptoms. One patient had myelodysplastic syndromes. One patient presented with an inflammatory bowel disease (IBD)-like phenotype. Patients presented with combined immunodeficiency. The proportions of naïve CD4+ and naïve CD8+ T cells decreased notably in five patients. All patients harbored compound heterozygous mutations in the LIG4 gene, which consisted of a missense mutation (c.833G > T, p.R278L) and a deletion shift mutation, primarily c.1271_1275delAAAGA (p.K424Rfs*20). Two other deletion mutations, c.1144_1145delCT and c.1277_1278delAA, were novel. Patients with p.K424Rfs*20/p.R278 may have milder dysmorphism but more significant IgA/IgM deficiency compared to the frequently reported genotype p.R814X/p.K424Rfs*20. One patient underwent umbilical cord blood stem cell transplantation (UCBSCT) but died. Conclusions The present study reported the clinical and molecular characteristics of a Chinese cohort with LIG4 syndrome, and the results further expand the phenotypic and genotypic spectrum and our understanding of genotype-to-phenotype correlations in LIG4 syndrome.

Activation of RIPK1 controls TNF-mediated apoptosis, necroptosis and inflammatory pathways1. Cleavage of human and mouse RIPK1 after residues D324 and D325, respectively, by caspase-8 separates the RIPK1 kinase domain from the intermediate and death domains. The D325A mutation in mouse RIPK1 leads to embryonic lethality during mouse development2,3. However, the functional importance of blocking caspase-8-mediated cleavage of RIPK1 on RIPK1 activation in humans is unknown. Here we identify two families with variants in RIPK1 (D324V and D324H) that lead to distinct symptoms of recurrent fevers and lymphadenopathy in an autosomal-dominant manner. Impaired cleavage of RIPK1 D324 variants by caspase-8 sensitized patients' peripheral blood mononuclear cells to RIPK1 activation, apoptosis and necroptosis induced by TNF. The patients showed strong RIPK1-dependent activation of inflammatory signalling pathways and overproduction of inflammatory cytokines and chemokines compared with unaffected controls. Furthermore, we show that expression of the RIPK1 mutants D325V or D325H in mouse embryonic fibroblasts confers not only increased sensitivity to RIPK1 activation-mediated apoptosis and necroptosis, but also induction of pro-inflammatory cytokines such as IL-6 and TNF. By contrast, patient-derived fibroblasts showed reduced expression of RIPK1 and downregulated production of reactive oxygen species, resulting in resistance to necroptosis and ferroptosis. Together, these data suggest that human non-cleavable RIPK1 variants promote activation of RIPK1, and lead to an autoinflammatory disease characterized by hypersensitivity to apoptosis and necroptosis and increased inflammatory response in peripheral blood mononuclear cells, as well as a compensatory mechanism to protect against several pro-death stimuli in fibroblasts.

Accumulating evidence indicates that RIPK1 is associated with inflammation and apoptotic. RIPK1 deficiency leads to proinflammatory signaling impaired. However, only few patients with homozygous loss-of-function mutation in RIPK1 gene had been reported until now. Here, we report a Chinese combined immunodeficiency patient. He had recurrent infection, diarrhea after 3 months old. Immune function indicated that T, B and NK cells decreased significantly but immunoglobulins approximately remained normal. Whole-exome sequencing indicated that he had novel compound heterozygous mutations (c.998 C > A from his mother and c.1934 C > T from his father) in RIPK1 gene, which were confirmed by Sanger sequencing. Our study reports novel mutations in RIPK1 gene and new phenotype of patient with RIPK1 deficiency. Keywords: Combined immunodeficiency, Inflammatory bowel disease, Mutation, RIPK1

T cell receptor (TCR) diversity is clearly related to protection from infection. However, the characteristics of TCR diversity in neonates are not clear. In this study, we investigated the TCR diversity of neonates with sepsis. Twenty neonates with severe sepsis and eight matched neonates without infection were enrolled in the study. For the neonates with sepsis, EDTA-anticoagulated blood was collected on day 1 after the diagnosis of sepsis and on day 7 of treatment. For the neonates without infection, blood was collected one time. DNA was extracted from peripheral blood mononuclear cells. The complementarity determining region 3 (CDR3) gene was analysed by multiplex PCR and high-throughput sequencing. The CDR3 types and lengths were similar in patients and healthy controls. There was a significant difference in VJ gene usage among the three groups. Compared to the healthy neonates, the neonates with sepsis had different VJ pairs and generated different clonotypes. Although the TCR β-chain diversity was generally lower in the neonates with sepsis, there was no significant difference in TCR β-chain diversity between the patients and the healthy controls. Our data showed the characteristics of the TCR repertoire in neonates with sepsis, which represents a potentially valuable data set. This result is useful for understanding neonatal susceptibility to infection.

Background Solute carrier family 19 member 2 (SLC19A2) gene deficiency is one of the causes of permanent neonatal diabetes mellitus (PNDM) and can be effectively managed by thiamine supplementation. Herein we report on a male patient with a novel SLC19A2 mutation and summarize the clinical characteristics of patients with SLC19A2 deficiency. Methods The genetic diagnosis of the patient with PNDM was made by sequencing and quantitative polymerase chain reaction. The clinical characteristics of PNDM were summarized on the basis of a systematic review of the literature. Results The patient with PNDM had c.848G>A (p.W283X) homozygous mutation in SLC19A2. His father had a wild-type SLC19A2 (c.848G) and his mother was c.848G/A heterozygous. The patient and his father both had a diploid genotype (c.848A/A and c.848G/G). After oral thiamine administration, the patient's fasting C-peptide levels increased gradually, and there was a marked decrease in insulin requirements. A search of the literature revealed that thiamine treatment was effective and improved diabetes in 63% of patients with SLC19A2 deficiency. Conclusions A novel SLC19A2 mutation (c.848G>A; p.W283X) was identified, which was most likely inherited as segmental uniparental isodisomy. Insulin insufficiency in PNDM caused by SLC19A2 deficiency can be corrected by thiamine supplementation. The differential diagnosis of SLC19A2 deficiency should be considered in children with PNDM accompanied by anemia or hearing defects to allow for early treatment.

Although many studies have investigated Mendelian susceptibility to mycobacterial disease (MSMD) worldwide, there is no report of the long-term clinical management and prognosis for MSMD in China. This is a cohort study from January 2000 to June 2018. Three hundred and twenty-four patients with bacillus Calmette-Guerin (BCG) infection were diagnosed during this period, and those with MSMD diagnosed by genetic and functional experiments were enrolled in the study. The clinical and genetic characteristics and management of these MSMD patients were summarized. Thirty patients diagnosed with MSMD were followed up. The age at the follow-up end point ranged from 5 to 173 months. Among the patients, IL12RB1 mutations were identified in 22, IFNGR1 mutations in 5, STAT1 mutations in 2, and IFNGR2 mutation in 1. The medium age at onset was 3 months. BCG infection involved multiple organs, including regional infection (8/30; 26.7%) or distant or disseminated infection (22/30; 73.3%). Ten percent (30/324) of patients with BCG infection had a confirmed MSMD diagnosis. Protein expression of IL12RB1 or IFNGR1 was decreased in all patients with IL12RB1 or IFNGR1 mutation, respectively, as indicated by flow cytometry. In addition, 77.8% of patients received rhIFN-γ treatment, which can improve the prognosis of patients with IL12RB1 deficiency. Two patients received stem cell transplantation. Twenty-five patients remained alive at the time of publication. MSMD is an important cause of BCG infection. Flow cytometric detection of IL12RB1 and IFNGR1 expression is very useful for rapid MSMD diagnosis. rhIFN-γ therapy is effective in patients with MSMD, particularly improving prognosis in those with IL12RB1 deficiency.

We aimed to report the characteristics of leukocyte adhesion deficiency-I (LAD-I) and four novel mutations in the ITGB2 gene in a Chinese cohort. Seven patients with LAD-I were reported in our study. Clinical manifestations and immunological phenotypes were reviewed. The expression of CD18 was detected by flow cytometry. Next-generation sequencing (NGS) and Sanger sequencing were performed to identify gene mutations. The mean onset age of all the patients was 1.3 months. Recurrent bacterial infections of the skin and lungs were the most common symptoms. Most patients (6/7) had delayed cord separation. The number of white blood cells (WBC) was increased significantly, except that two patients had a mild increase in the number of WBC during infection-free periods. The expression of CD18 was very low in all patients. Homozygous or compound heterozygous mutations in the ITGB2 gene were identified in each patient. Four mutations were novel, including c.1794dupC (p.N599Qfs*93), c.1788C>A (p.C596X), c.841-849del9, and c.741+1delG. Two patients had large deletions of the ITGB2 gene. Five patients were cured by hematopoietic stem cell transplantation (HSCT). This study reported the clinical and molecular characteristics of a Chinese patient cohort. It is helpful in understanding the current status of the disease in China.

Recent studies have suggested associations between certain genetic variants and susceptibility to persistent pulmonary hypertension of the newborn (PPHN). The aim of the study was to evaluate the association of EDN1, NOS3, ACE and VEGFA genes with PPHN. Neonates with respiratory distress were enrolled in the study, whose gestational age ≥34 weeks, age ≤3 days. They were divided into PPHN and non-PPHN group. The EDN1, NOS3, ACE and VEGFA genes were detected by next-generation sequencing and the results were validated by Sanger sequencing. Serum endothelin-1 (ET-1) levels were quantified by ELISA. A total of 112 neonates were enrolled (n = 55 in PPHN group; n = 57 in non-PPHN group). There is a significantly difference in the genotype distribution of EDN1 rs2070699 between the PPHN and non-PPHN group (P = 0). A higher frequency of the rs2070699 T allele was observed in the PPHN group (54.5% vs 27.2%; OR = 3.89; 95%CI 1.96–7.72). The rs2070699 T allele was associated with higher ET-1 levels (3.333 ± 2.517 pg/mL vs 1.223 ± 0.856 pg/mL; P = 0.002) and a longer ventilation period (5.8 ± 2.6 days vs 3.6 ± 3.3 days; P = 0). The results suggest there is an association between EDN1 and PPHN. The presence of the rs2070699 T allele increased the risk of PPHN in neonates with respiratory distress.