Clinical And Molecular Analysis Of Higm

Objective: To analyze the clinical, laboratory and molecular featuresof Chinese children with Hyper-IgM syndrome (HIGM) phenotype, in anattempt to provide genetic diagnosis, detect carriers and provide geneticcounseling, and to explore the correlation between the proportion ofCD4+CD25+FoxP3+Treg, Th17and Th1in peripheral blood and the risk ofautoimmune occurrence in these patients.Methods: Ten children with HIGM phenotype admitted to Children’sHospital of Chongqing Medical University during November2011andMarch2013were enrolled in this study. Their clinical and laboratory datawere analyzed and blood samples were collected. CD40L and CD40expression in PBMCs were detected by flow cytometry (FCM). CD40L,AID, UNG, CD40and NEMO gene were amplified by polymerase chainreaction (PCR) and directly sequenced in patients and their familymembers. The CD40L gene of two fetus amniotic fluid cells, whosemother were mutant CD40L gene carriers, was analyzed by PCR-directedsequencing. The proportion of CD4+CD25+FoxP3+Treg, Th17and Th1inPBMCs was detected by FCM.Results: In the present study, the mean age of onset of the ten patients was7.8±6.6months while the mean age at diagnosis was4.6±2.2years old.All of the patients presented recurrent infections, including repeatedpneumonia （100%）， otitis media (80%), diarrhea (60%), lymphoidtuberculosis (50%), oral ulcer (40%) and muguet (30%). Besides, somepatients showed intermittent arthralgia (30%), malnutrition (20%),abnormal liver function (20%), hepatomegaly (20%), hematochezia andanemia (20%). Eight patients presented typical immunological phenotypewith low levels of IgG and IgA, and normal to high level of IgM. Whilepatient P3had high level of IgA; patient P5showed normal levels of IgAand IgM. Seven patients showed abscence of CD40L expression onactivated T cells. Six different CD40L gene mutations were identified in7patients, including five deletion mutations, one nonsense mutation, onemissense mutation. Two of them were novel mutations (400delA，89delT).Three cases of the patient’s mother were carriers by CD40L gene analysis.Patient P7showed no expression of CD40L on activated T cells, but nomutation was found in genomic DNA and absence in cDNA. Two fetusshowed the same gene mutations as their brothers and the pregnancies werethen terminated. The percentage of CD4+CD25+FoxP3+Treg decreasedwhen compared with healthy control (1.648±0.577%N=6VS3.895±1.570%N=6，P=0.015). Besides, the percentage of Th17increased butwithout statistical significance (2.217±1.209%N=6VS0.983±0.714%N=6，P=0.057). The percentage of Th1increased obviously when compared with healthy control (35.100±14.564%N=6VS13.000±7.618%N=6， P=0.008）.Conclusion: Ten HIGM patients in the present study showed earlyonset as well as severe and complicated manifestations. Six distinct CD40Lgene mutations were identified in these patients, two of which were novel.CD40L expression detected by FCM is a qucik and effective method fordiagnosis of X-HIGM. Genetic analysis could make definite diagnosis ofHIGM, identify mutation carriers and provide genetic counseling, whichimportant for early diagnosis, proper treatment and hematopoietic stem celltransplantation. The decrease in the percentage ofCD4+CD25+FoxP3+Treg and increase in the percentage of Th17and Th1inthe peripheral blood may be associated with the occurrence ofautoimmunity in HIGM patients.