3.1 Overview
Table 1 showed the general information of patients. A total of 12 patients, including seven males and five females, were all from nonconsanguineous families. 11 patients were diagnosed with STAT3 LOF mutation and one patient (P12) was STAT3 GOF mutation. 11 STAT3-deficient patients were diagnosed at a median age of 4.74 years (0.5–12 years old) while median onset age was 1.89 years (neonate-11.5 years old), involving in 5 infantile-onset patients (P1, P7, P8, P10 and P11). The onset age of STAT3 GOF patient was 13 years. All the patients were full-term gestation, either cesarean Sect. (2/12) or vaginal delivery (10/12).
3.2 Infectious complications of 11 STAT3 LOF patients
All patients suffered from eczema, especially in facial and scalp areas. More seriously, some of eczema spread from scalp to truncus. Recurrent respiratory infection was most common in our patients (11/11). Moreover, the infection also had been found in other systems, such as otitis media in 5 (P1, P3, P4, P5 and P6), rhinitis in 1 (P10) and diarrhea in 2 (P7 and P8). Rotavirus was detected in P8. Staphylococcus aureus infection was one of the noteworthy characteristics in STAT3-deficient patients. Almost half of the patients (P2, P3, P4, P5, P7 and P9) was recognized as Staphylococcus aureus pneumonias confirmed by either sputum, blood, or bronchoalveolar lavage fluid (BALF) culture. Abscesses were occurred in 8 patients in a different body part, consisting of the lung in 5 (P2, P3, P7, P9 and P10), the scalp in 4 (P2, P4, P7 and P10), the abdomen in 1(P7) and the buttock in 1(P1). What’s more, P7 and P10 implemented partial lung lobectomy. In our patients, about half of them (5/11. P3, P5, P6, P8 and P9) remarkably accompanied with chronic mucocutaneous candidiasis (CMC) verified by microscopic examination of fungal or fungal culture. Eight patients (8/11. P2, P4, P5, P6, P7, P9, P10 and P11) had a fever. (Figure. 1).
EBV-DNA was measured in PBMCs for 2 out of 11 patients (P7 and P10) and the viral load was 9.00E + 03 and 2.60E + 03, respectively. Cytomegalovirus (CMV)-DNA was also detected in blood, urine and BALF for two patients (P6 and P10) with the virus load in 8.69E + 04 and 2.00E + 05, respectively.
3.3 Immunological presentation of 11 STAT3 LOF patients
Eosinophil count increased in different degrees (470 ~ 5860 cells/µL, reference range: 30–500 cells/µL). (Table 1). Elevated serum IgE concentration was considered as one of the most prominent characteristics in STAT3-deficient patients. Apart from P8 (67.2 KU/L) and P11 (43.87 KU/L), other patients encountered high serum IgE levels range from 1841.29 KU/L to 17310.4 KU/L (the average value range was < 100 KU/L). IgG, IgA and IgM level approximately remained normal. (Table 2).
Lymphocytes roughly remained normal in patients, although the absolute number of Total T cells (in P1 and P4), CD4 T cells (in P4 and P7) and Total B cells (in P5 and P7) slightly increased. Four patients (P3, P7, P9, P10) had decreased NK cells. (Table 2). At the same time, we performed T cells and B lymphocytes subpopulation for three patients who had will to draw blood. All of them presented with ascended double-negative T cells and decreased memory B cells. P8 had two-fold higher effector memory cytotoxic T cells while P9 presented two-fold higher terminally differentiated effector memory cytotoxic T cells. P4 showed dramatic decline in γδ T cells. (Table 3).
3.4 Non-immunological abnormalities of 11 STAT3 LOF patients
Two patients (2/11. P5 and P7) suffered from growth retardation. Retention of primary teeth also happened in three patients (3/11. P1, P2 and P7). Three patients (3/11. P1, P5 and P7) experienced facial features. Broad nose and high-arched palate were displayed in P1. Meanwhile, P5 showed coarse facies and prominent forehead, the same with P7. Skeletal abnormality, principally pigeon chest, only occurred in P7. Furthermore, enlarged lymph nodes, particularly in the cervical and inguinal region could be observed in 4 patients (P2, P4, P6 and P7). Splenomegaly was detected in P5 and P7, and the former also suffered from enlargement of the liver. Furthermore, P5 and P10 appeared food allergy. (Figure. 1).
As previously reported [13], the National Institutes of Health (NIH) scores were the most common accepted clinical STAT3-deficient diseases scoring system. In our study, 5 out of 11 patients reached or exceeded 40 points and two patients (P8 and P11. They had been evaluated 27 and 21 scores, respectively) were below the diagnostic standard.
3.5 The patient harboring STAT3 GOF mutation
P3 suffered from repeated cough, nasitis, diarrhea and CMC. Diffusely enlarged lymph node and hepatosplenomegaly was found in this patient. She also presented autoimmune hemolytic anemia, reduced white blood cells and platelet, acratia, diabetes, alopecia and delayed pubertal development. IgE level was 221.65 KU/L. For the lymphocyte subsets, the patient suffered from a severe reduction of all kinds of lymphocytes. EBV-DNA viral load was 4.05E + 04 in PBMCs and mycoplasma viral load was 2.42E + 08.
3.6 Mutation of STAT3 gene
WES suggested those patients had heterozygous mutations in STAT3. (Figure. 2). As shown in Table 1 that other variants were all de nove mutation type except for P11 whose variants derived from his father (c.994C > A; p.H332N). We noticed that c. 1144C > T(R382W) was the most common spot in our study, which was identified in 3 patients (27.27%), followed by c. 1311C > A(H437Q) in 2 patients (18.18%). H437Q and R609T were two novel mutations that could not be found in OMIM and clinvar databases. Moreover, H437Q and R609T were supposed as disease-causing in Mutationtaster; meanwhile they were also predicated as a deleterious mutation by software PopViz [14]. (Figure. 3). What's more, the mutation for the GOF STAT3 patient was a known mutation (1261G > A; p.G421R) and proven to be GOF by Milner [15].
3.7 Therapy
All the 11 STAT3 LOF patients were given prophylactic antimicrobials and symptomatic treatment. Eight patients (P1, P2, P3, P4, P5, P6, P8 and P11) obtained a notable improvement of their eczema, respiratory infection and candida infections after received intravenous immunoglobulin (IVIG) in the dose of 400–600 mg/kg/m. The GOF STAT3 patient received treatment with the anti-IL6R monoclonal antibody tocilizumab and got a stable condition with less alopecia, normal blood glucose and less infection.