Analysis Of Deadly Risk Factors Of Wiskott-Aldrich Syndrome And Founder Effect Of LIG4 Mutation Hotspots In Chinese Patients

PART Ⅰ CLINICAL CHARACTERISTICS AND RISK FACTORS OF DEATHS IN PATIENTS WITH WISKOTT-ALDRICH SYNDROMEObjective: To explore the clinical characteristics and risk factors of deaths in pediatric patients with Wiskott-Aldrich syndrome(WAS)and to raise awareness among pediatricians.Method: Clinical data of 40 death cases of pediatric patients with WAS,who visited the Immunology Division of Children’s Hospital affiliated to Chongqing Medical University between January 2007 and August 2020 were retrospectively analyzed(death group).One hundred and twenty five surviving patients with Wiskott-Aldrich syndrome during the same period were included as control group(survival group).Kolmogorov-Smirnov test,F test,Welch’s approximate t-test and Fisher’s exact probability test were used to compare and analyze the general situation,clinical manifestations,laboratory tests and treatment between the two groups,and risk factors were analyzed by multivariate Logistic regression analysis.Result: A total of 165 patients with Wiskott-Aldrich syndrome were included in this study,all of whom were male.Most of the children in the death group(37 cases,92.5%)had a typical triad of eczema,thrombocytopenia and repeated infection with median age of 19 months(3～140 months).The mean WAS score was 4.13±0.82 in the death group and 3.14 ± 1.22 in the survival group.The episode rates of recurrent infection/severe infection,intracranial hemorrhage and eczema in the death group were significantly higher than those in the survival group(all p<0.05),but there was no significant difference in the frequency of autoimmunity(p = 0.898).Detailed phenotying of peripheral lymphocytes and immunoglobulin detection in death group and alive group did not show statistical significance of differences.TRECs counts showed significant differences between 0 to 1 age group(30 copy numbers/ul(13,75)vs.132 copy numbers/ul(34,192),p = 0.0431)and 1 to 2 years old group(16 copy numbers/ul(9,33.75)vs.53 copy numbers/ul(30,73.75),p = 0.0182).Infection(22 cases,55.0%)and intracerebral haemorrhage(15 cases,37.5%)were the main causes of death,3 cases(7.5%)died of severe GVHD(Graft-versus-host disease)after transplantation.Eczema rate was also statistically significant between the two groups(90.0% vs.72.0%,p =0.02),and autoimmune(25.0% vs.24.0%,p = 0.898)did not become a major risk factor statistically.Logistic regression mode was used to analyze the risk factors for death in WAS patients.The results indicated that repeated infection/severe infection and non-use of IVIG replacement therapy were risk factors for death in Chinese WAS patients(p < 0.05).Conclusion: Recurrent/severe infection is the main risk factor of deaths in patients with WAS.Regular IVIG treatment can improve the survival rate of patients with WAS.PARTⅡTHE LIG4 P.R278 L HOTSPOT MUTATION REVELS A FOUNDER EFFECT IN A CHINESE POPULATIONObjective: To explore the founder effect of LIG4 syndrome,and to provide basis for the formulation of precision therapy such as disease screening and base editing.Method: Clinical data,immune and genetic characteristics of 15 children with LIG4 syndrome,who visited the Rheumatology Department of Children’s Hospital affiliated to Chongqing Medical University between January 2011 and September 2020 were retrospectively analyzed.The haplotypes were constructed by Plink and Haploview linkage analysis using the 1000 human genome database.The haplotype analysis of hot spot mutation P.R278 L was performed.Result: A total of 15 children with LIG4 syndrome patients were included in this study,including 8 males and 7 females.The mean age of onset of clinical symptoms was 8 months(1~23 months),and the median time to diagnosis was 18 months.Infection was the most common form of disease,followed by hemocytopenia,and all children had microcephaly and growth retardation to varying degrees.So far,eight children have died,and only two have received hematopoietic stem cell transplantation(P9 died of infection 6 months after transplantation).The immunophenotype of most patients was T-B-NK+,and the evaluation of immune function suggested that TRECs and KRECs were significantly reduced,lymphocyte proliferate much worse,and the complexity of TCR was limited in patients.Gene analysis showed that p.R278 L mutation was a unique hot spot mutation in Chinese LIG4 syndrome patients.In this study,three haplotypes were found in LIG4 syndrome patients harbored the p.R278 L mutation.The most common haplotype was GGACTACT(53.8%),which had a low frequency in the normal population(CHS,19.5%;CHB,17.5%),and decreased haplotype diversity.These data suggesting that the LIG4 p.R278L mutation has a founder effect in the Chinese population.Conclusion: The clinical phenotype and severity of LIG4 syndrome fluctuated greatly,and haplotype analysis confirmed the founder effect of LIG4 p.R278 L hot spot mutation in the Chinese population.