Hyperimmunoglobulin E syndrome: Genetics, immunopathogenesis, clinical findings, and treatment modalities

Neutrophil-avid nanocarrier uptake by STAT3 dominant-negative hyper-IgE syndrome patient neutrophils

Recurrent infections are a hallmark of STAT3 dominant-negative hyper-IgE syndrome (STAT3 HIES), a rare immunodeficiency syndrome previously known as Jobs syndrome, along with elevated IgE levels and impaired neutrophil function. We have been developing nanoparticles with neutrophil trophism that home to the sites of infection via these first-responder leukocytes, named neutrophil-avid nanocarriers (NANs). Here, we demonstrate that human neutrophils can phagocytose nanogels (NGs), a type of NAN, with enhanced uptake after particle serum opsonization, comparing neutrophils from healthy individuals to those with STAT3 HIES, where both groups exhibit NG uptake; however, the patient group showed reduced phagocytosis efficiency with serum-opsonized NANs. Proteomic analysis of NG protein corona revealed complement components, particularly C3, as predominant in both groups. Difference between groups includes STAT3 HIES samples with higher neutrophil protein and lower acute-phase protein expression. The study suggests that despite neutrophil dysfunction in STAT3 HIES, NANs have potential for directed delivery of cargo therapeutics to improve neutrophil infection clearance.

Elevated Immunoglobulin E Serum Levels: Possible Underlying Factors That Can Cause an Inborn Error of Immunity in the Pediatric Population with Recurrent Infections

Elevated immunoglobulin E (IgE) levels are commonly associated with allergies. However, high IgE levels are also found in several other infectious and non-infectious disorders. Elevated IgE levels typically suggest allergies, eczema, or recurrent skin infections. Hyperimmunoglobulin E (hyper-IgE) levels typically reflect a monogenic atopic condition or inborn immune defects with an atopic phenotype. The aim of our research is to investigate and observe the clinical characteristics of children with increased IgE levels who have previously manifested infectious diseases. Furthermore, the retrospective study considers other factors, such as demographic characteristics (sex, area/environment, and age), and their effect on IgE serum levels. To answer this question, we conducted a one-year hospital-based retrospective study that included 200 hospitalized children who had at least two viral or bacterial infections in the six months preceding hospitalization. Measurements of IgE and allergen panels (respiratory and digestive) using blood samples revealed that individuals who tested positive for the body's synthesis of hyper-IgE were not observably allergic to any potential allergens despite having higher total serum IgE. According to the results, there was a strong correlation between elevated IgE serum levels and a history of infectious diseases among the patients.

Antibiotic susceptibility and clonal distribution of Staphylococcus aureus from pediatric skin and soft tissue infections: 10-year trends in multicenter investigation in China

Background

Skin and Soft Tissue Infections (SSTIs) Surveillance Network of S. aureus In Pediatrics in China was established in 2009 to routinely report epidemiological changes. We aimed to monitor the present antibiotic sensitivity and molecular characteristics of S. aureus and methicillin-resistant S. aureus (MRSA) from SSTIs in children nationwide and track the changes over the past decade.

Methods

Patients diagnosed with SSTIs from the dermatology departments of 22 tertiary pediatric hospitals in seven geographical regions of China were recruited continuously from May 2019 to August 2021. S. aureus was isolated, and its sensitivity to 15 antimicrobials was evaluated using the broth microdilution method. The molecular characteristics of the MRSA isolates were determined through multilocus sequence typing (MLST) and staphylococcal cassette chromosome mec (SCCmec) typing. The presence of the Panton-Valentine leukocidin gene (pvl) was determined.

Results

The detection rate of S. aureus was 62.57% (1379/2204), among which MRSA accounted for 14.79% (204/1379), significantly higher than the result in previous study in 2009-2011 (2.58%, 44/1075). Compared with previous study, the sensitivity to cephalosporins and fusidic acid decreased to varying degrees, while that to chloramphenicol, ciprofloxacin, clindamycin, erythromycin, gentamicin, penicillin, and tetracycline increased significantly. The sensitivity to mupirocin, trimethoprim/sulfamethoxazole (TRISUL), and rifampicin still maintained at a high level (97.90%, 99.35% and 96.66% respectively). The leading multidrug resistance pattern of MRSA and methicillin-sensitive S. aureus (MSSA) were erythromycin-clindamycin-tetracycline (55.84%; 43/77) and erythromycin-clindamycin-chloramphenicol (27.85%, 44/158) respectively. 12 high-level mupirocin-resistant strains were detected, and notable differences in geographical distribution and seasonal variation were observed. The main types of MRSA were ST121 (46.08%, 94/204), followed by ST59 (19.61%, 40/204). SCCmec V (65.69%, 134/204) and SCCmec IV (31.86%, 65/204) were dominant epidemic types. ST121-V, ST59-IV, and ST22-V were the most prevalent clones nationwide. The detection rate of pvl had increased markedly from 9.09% (4/44) in 2009-2011 to 22.55% (46/204) in 2019-2021 (P<0.05).

Conclusion

The antibiotic sensitivity and molecular characteristics of S. aureus from pediatric SSTIs has changed significantly over the past decade. To standardize medical care, provide timely and reasonable clinical treatment, and effectively manage infection control, Chinese pediatric SSTIs guidelines are urgently needed.

Allergic bronchopulmonary aspergillosis with marked peripheral blood eosinophilia and pulmonary eosinophilia: A case report

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) is an immune-related pulmonary disease caused by sensitization of airway by Aspergillus fumigatus. The disease manifests as bronchial asthma and recurring pulmonary shadows, which may be associated with bronchiectasis. The diagnosis of ABPA mainly depends on serological, immunological, and imaging findings. Pathological examination is not necessary but may be required in atypical cases to exclude pulmonary tuberculosis, tumor, and other diseases through lung biopsy.

CASE SUMMARY

An 18-year-old man presented with recurrent wheezing, cough, and peripheral blood eosinophilia. Chest computed tomography showed pulmonary infiltration. There was a significant increase in eosinophils in bronchoalveolar lavage fluid. There was no history of residing in a parasite-endemic area or any evidence of parasitic infection. Pathologic examination of bronchoalveolar lavage fluid excluded fungal and mycobacterial infections. The patient was receiving medication for comorbid diseases, but there was no temporal correlation between medication use and clinical manifestations, which excluded drug-induced etiology. Histopathological examination of lung biopsy specimen showed no signs of eosinophilic granulomatosis with polyangiitis, IgG4-related diseases, or tumors. The diagnosis of ABPA was considered based on the history of asthma and the significant increase in serum Aspergillus fumigatus-specific immunoglobulin (Ig)E. Eosinophil-related diseases were excluded through pathological biopsy, which showed typical pathological manifestations of ABPA.

CONCLUSION

The possibility of ABPA should be considered in patients with poorly controlled asthma, especially those with eosinophilia, lung infiltration shadows, or bronchiectasis. Screening for serum IgE, Aspergillus fumigatus-specific IgE and IgG, and alveolar lavage can help avoid misdiagnosis.

AAV-monoclonal antibody expression protects mice from Ebola virus without impeding the endogenous antibody response to heterologous challenge

Filoviruses cause severe hemorrhagic fever with case fatality rates as high as 90%. Filovirus-specific monoclonal antibodies (mAbs) confer protection in nonhuman primates as late as 5 days after challenge, and FDA-approved mAbs REGN-EB3 and mAb114 have demonstrated efficacy against Ebola virus (EBOV) infection in humans. Vectorized antibody expression mediated by adeno-associated virus (AAV) can generate protective and sustained concentrations of therapeutic mAbs in animal models for a variety of infectious diseases, including EBOV. Here we demonstrate that AAV6.2FF-mediated expression of murine IgG2a EBOV mAbs, 2G4 and 5D2, protects from mouse-adapted (MA)-EBOV infection with none of the surviving mice developing anti-VP40 antibodies above background. Protective serum concentrations of AAV6.2FF-2G4/AAV6.2FF-5D2 did not alter endogenous antibody responses to heterologous virus infection. AAV-mediated expression of EBOV mAbs 100 and 114, and pan-ebolavirus mAbs, FVM04, ADI-15878, and CA45, as human IgG1 antibodies conferred protection against MA-EBOV at low serum concentrations, with minimum protective serum levels as low as 2 μg/mL. Vectorized expression of murine IgG2a or human IgG1 mAbs led to sustained expression in the serum of mice for >400 days or for the lifetime of the animal, respectively. AAV6.2FF-mediated mAb expression offers an alternative to recombinant antibody administration in scenarios where long-term protection is preferable to passive immunization.

Dedicator of cytokinesis 8 deficiency and hyperimmunoglobulin E syndrome: A case report

RATIONALE

Hyperimmunoglobulin E syndrome (HIES) is a rare and complex immunoregulatory multisystem disorder characterized by recurrent eczema, skin and sinopulmonary infections, elevated serum immunoglobulin E levels, and eosinophilia. Onset is most likely in childhood, although infrequent adult cases have been reported. Early diagnosis is important. The use of the National Institutes of Health scoring system and the HIES signal transducer and activation of transcription 3 score can standardize the diagnosis of HIES.

PATIENT CONCERNS

A 19-year-old woman presented with complaints of dry cough, pyrexia, dyspnea, and recurrent pneumonia. She had a history of milk allergy, recurrent eczema, suppurative otitis media, chalazia, and aphthous ulcers. Her parents had a consanguineous marriage.

DIAGNOSIS

HIES; severe pneumonia.

INTERVENTIONS

Voriconazole (200 mg iv 2 times/d) and flucytosine (1 g orally 4 times/d) for 3 weeks were administered, followed by oral administration of fluconazole for 3 weeks.

OUTCOMES

The patient experienced near-complete remission of her respiratory symptoms. The patient was followed-up for one and a half years. During the follow-up, the patient presented again with cough and dyspnea and was again admitted to hospital. After being hospitalized for 3 weeks of antibiotic treatment, the patient experienced near-complete relief of her respiratory symptoms.

LESSONS

Regardless of patient age, it is important to consider the possibility of HIES when a patient has recurrent eczema, skin and sinopulmonary infections, elevated serum immunoglobulin E levels, and eosinophilia. Early diagnosis and intervention are essential to improve prognosis.

Retinal Occlusive Vasculitis in a Patient with Hyperimmunoglobulin E Syndrome

Background

Hyperimmunoglobulin E syndrome (HIES), or Job's syndrome, is a primary immunodeficiency disorder that is characterized by an elevated level of IgE with values reaching over 2000 IU (normal < 200 IU), eczema, and recurrent staphylococcus infection. Affected individuals are predisposed to infection, autoimmunity, and inflammation. Herein, we report a case of HIES with clinical findings of retinal occlusive vasculitis. Case Presentation. A 10-year-old boy with a known case of hyperimmunoglobulin E syndrome had exhibited loss of vision and bilateral dilated fixed pupil. Fundoscopic examination revealed peripheral retinal hemorrhaging, vascular sheathing around the retinal arteries and veins, and vascular occlusion in both eyes. A fluorescein angiography of the right eye showed hyper- and hypofluorescence in the macula and hypofluorescence in the periphery of the retina, peripheral arterial narrowing, and arterial occlusion. A fluorescein angiography of the left eye showed hyper- and hypofluorescence in the supranasal area of the optic disc. Macular optical coherence tomography of the right eye showed inner and outer retinal layer distortion. A genetic study was performed that confirmed mutations of the dedicator of cytokinesis 8 (DOCK 8). HSV polymerase chain reaction testing on aqueous humor and vitreous was negative, and finally, the patient was diagnosed with retinal occlusive vasculitis.

Conclusion

Occlusive retinal vasculitis should be considered as a differential diagnosis in patients with hyperimmunoglobulin E syndrome presenting with visual loss.

The other side of the coin: IgE deficiency, a susceptibility factor for malignancy occurrence

Since the discovery of IgE, almost all attention was given to conditions with elevated specific or total IgE levels such as atopy, type I hypersensitivity reactions, or parasitic infestations. Recent prospective and retrospective studies show that having very low IgE levels, such as those seen in IgE deficiency (IgE<2.5 kU/L), is not without clinical consequences. Patients with ultra-low IgE levels have an elevated risk of cancer of any type. These results are in agreement with murine models research which demonstrated that grafted tumors grow faster and bigger on an IgE knockout background. The novel finding that IgE deficiency is a susceptibility factor for cancer, fits very well with the AllergoOncology concept. The reports on a beneficial, cytotoxic function of IgE, in cooperation with its high (FcεRI) and low (FcεRII, CD23) affinity IgE receptors resulting in tumor cell phagocytosis, propose a role of IgE in cancer surveillance. It appears that not only deficiency of serum IgE, but also lack of tissue-bound IgE is important in malignancy susceptibility in these patients. As such, IgE deficient individuals with absent serum and cell-bound IgE as suggested by negative type I hypersensitivity skin tests, are at the highest risk for a malignancy diagnosis. In contrast, IgE deficient individuals with cell-bound IgE depicted through positive type I hypersensitivity skin tests, have lower rates of malignancy diagnosis. The present report discusses the evidence and potential role of ultra-low IgE as a novel biomarker for cancer susceptibility.

An Unusual Pattern of Premature Cervical Spine Degeneration in STAT3-LOF

Loss of function mutations in STAT3 (STAT3-LOF; autosomal dominant hyper-IgE (Job's) syndrome) are associated with a variety of musculoskeletal manifestations, including scoliosis, osteoporosis, and minimal trauma fractures. This retrospective magnetic resonance (MR) imaging study sought to characterize an unusual pattern of cervical spine degeneration among a cohort of STAT3-LOF patients. Cervical spine MR images of the STAT3-LOF cohort (n = 38) were assessed for a variety of degenerative changes and compared to age-matched groups of controls (n = 42) without known immune or musculoskeletal abnormalities. A unique pattern of premature cervical spine degeneration was identified among the STAT3-LOF cohort which included straightening and eventual reversal of the normal cervical lordosis, mainly due to multi-level spondylolisthesis, as well as early development of spinal canal narrowing, cord compression, and myelomalacia. Cervical spine degeneration in the STAT3-LOF cohort was significantly worse than controls in both the 30-45 and 45 + age groups. Moderate to severe degenerative changes were present after age 30, and markedly worsened over time in several cases. Bone mineral density (BMD) had a moderate negative correlation with cervical degeneration severity and a strong negative correlation with age among STAT3-LOF participants. Cervical degeneration in STAT3-LOF appears to be progressive and could result in cord compromise if left unaddressed. Focused history and physical examination for signs of neurologic compromise as well as periodic MR imaging are thus recommended for the evaluation of premature cervical spine degeneration in STAT3-LOF patients after age 30 so that timely surgical interventions may be considered to prevent spinal cord damage and permanent neurological deficits.

On Two Cases with Autosomal Dominant Hyper IgE Syndrome: Importance of Immunological Parameters for Clinical Course and Follow-Up

Autosomal dominant hyper-IgE syndrome (AD-HIES) is a rare disease described in 1966. It is characterized by severe dermatitis, a peculiar face, frequent infections, extremely high levels of serum IgE and eosinophilia, all resulting from a defect in the STAT3 gene. A variety of mutations in the SH2 and DNA-binding domain have been described, and several studies have searched for associations between the severity of the clinical symptoms, laboratory findings, and the type of genetic alteration. We present two children with AD-HIES–a girl with the most common STAT3 mutation (R382W) and a boy with a rare variant (G617E) in the same gene, previously reported in only one other patient. Herein, we discuss the clinical and immunological findings in our patients, focusing on their importance on disease course and management.

Hyper IgE syndrome (Job syndrome) in Syria: a case report

Hyper IgE syndrome (HIES) is a medical condition that can be sporadic or hereditary. It consists of multiple overlapping primary immunodeficiency conditions and is characterized by a classical triad of high immunoglobulin E (IgE) levels, recurrent pneumonia with pneumatocele and recurrent cold skin abscesses from staphylococcus infections. Eosinophilia is also common in HIES patients. HIES is often underdiagnosed in Syria as it cannot be confirmed without genetic testing, which is unavailable across Syria for HIES. We present the first case from Syria of a suspected child with HIES that has some additional distinct features. Other cases in a regional country carried atypical novel mutations, which may indicate that these mutations may exist in Syria as well. However, our case had findings that were not reported with other HIES cases. Determining these genes in the case presented was not possible, and future studies need to overcome this hurdle.

Serum 25-Hydroxyvitamin D, Selenium, Zinc and Copper in Patients with Keratoconus

PURPOSE

To assess the possible association between keratoconus (KC) and serum levels of 25-hydroxyvitamin D (25OHD), Selenium (Se), Zinc (Zn), and Copper (Cu) and to compare it with age-matched healthy subjects.

METHODS

One hundred patients with KC and 100 normal subjects were included. The two groups were compared for serum 25OHD and serum levels of three trace elements: Se, Zn, and Cu. These factors were also compared between groups with different KC stages.

RESULTS

Serum levels of vitamin D, Zn, Cu, and Se were significantly different between the KC and normal groups (P = 0.006, P = 0.015, P = 0.004, and P = 0.038, respectively). Although a lower level of 25OHD was found in severe stages of KC, it was not significantly different among different KC groups (P = 0.441). KC stage groups were not significantly different for mean serum Zn, Cu, and Se (P = 0.130, P = 0.98, P = 0.113, respectively). Although the Cu/Zn ratio was higher in cases than in controls, there was no significant difference between the two groups and between KC stages (P = 0.168, P = 0.143, respectively).

CONCLUSION

Lower serum 25OHD, Cu, Zn, and Se were found in the KC group compared to the control group. The results of this study suggest that a lower antioxidative activity may be involved in the possible etiology of KC.

Electrochemical selection of a DNA aptamer, and an impedimetric method for determination of the dedicator of cytokinesis 8 by self-assembly of a thiolated aptamer on a gold electrode

The autosomal recessive-hyper immunoglobulin E syndromes (AR-HIES) are inherited inborn primary immunodeficiency disorders caused mainly by mutations in the dedicator of cytokinesis 8 (DOCK8) gene. A method is described for the selection of DNA aptamers against DOCK8 protein. The selection was performed by using a gold electrode as the solid matrix for immobilization of DOCK8. This enables voltammetric monitoring of the bound DNA after each selection cycle. After eight rounds of selection, high affinity DNA aptamers for DOCK8 were identified with dissociation constants (Kds) ranging from 3.3 to 66 nM. The aptamer which a K_d of 8.8 nM was used in an aptasensor. A gold electrode was modified by self-assembly of the thiolated aptamer, and the response to the DOCK8 protein was detected by monitoring the change in the electron transfer resistance using the ferro/ferricyanide system as a redox probe. The aptasensor works in the 100 pg.mL^-1 to 100 ng.mL^-1 DOCK8 concentration range, has a detection limit of 81 pg.mL^-1 and good selectivity over other proteins in the serum. Graphical abstractSchematic representation of an electrochemical screening protocol for the selection of DNA aptamer against dedicator of cytokinesis 8 protein using electrode as solid support for target immobilization.

Generation of human induced pluripotent stem cell lines (NIHTVBi011-A, NIHTVBi012-A, NIHTVBi013-A) from autosomal dominant Hyper IgE syndrome (AD-HIES) patients carrying STAT3 mutation

Autosomal dominant Hyper IgE syndrome (AD-HIES), a rare immune deficiency affecting fewer than one per million people, is caused by heterozygous deleterious mutations in STAT3. STAT3 signaling plays crucial roles in basic cellular functions affecting broad aspects of cellular homeostasis. Accordingly, in addition to immunological deficits, patients experience severe multisystem non-immunological features. Human induced pluripotent stem cells (hiPSC) are well established as in vivo disease models for various human pathologies. We describe the generation of iPSC from three AD-HIES patients. These iPSCs express pluripotency markers, differentiate into three germ layers, have normal karyotype and similar genome identity to parental cells.

Clinical Manifestation of Hyper IgE Syndrome Including Otitis Media

PURPOSE OF REVIEW

The hyper IgE syndromes (HIES) comprise a group of rare primary immunodeficiency disorders (PIDDs), which are characterized by extremely high serum IgE levels, eczema, recurrent skin and pulmonary infections. Both autosomal dominant (AD) HIES due to STAT3 mutations and autosomal recessive (AR) HIES due to PGM3, SPINK5, DOCK8 and TKY2 mutations have been reported. Here, we aim to summarize and compare the major clinical manifestations of different subtypes of HIES. We will also discuss otitis media, which usually do not get enough attention in HIES. Update and familiarity with these clinical features will help to make a better diagnose, assessment and treatment of HIES.

RECENT FINDINGS

Although hyper serum IgE levels have been identified in PGM3 deficiency and Comel-Netherton syndrome, PGM3 and SPINK5 genes were not included in the list of genetic etiologies of AR-HIES by the Expert Committee of the International Union of Immunological Societies until 2015. The identification of these HIES-causing genes greatly promoted the pathogenic mechanism studies of HIES. Also, in recent years, more clinical manifestations, which were often not of concern in HIES patients, have been shown to be highly related to HIES. For example, a significantly high frequency of vascular and gastrointestinal abnormities has been reported in STAT3-deficient AD-HIES patients. These new findings might help to provide new clues to the functional study of these HIES-related genes. This review summarizes and compares the major clinical manifestations of different subtypes of HIES, and we suggest that the incidence and severity of otitis media should not be underestimated in HIES patients.

A Novel STAT3 Gene Mutation Related Hyper-IgE Syndrome Misdiagnosed as Hidradenitis Suppurativa

Although Hyper-IgE Syndrome (HIES) is a rare immunodeficiency disorder, presenting symptoms may be as common as lung and skin infections. Symptoms are usually nonspecific such as recurrent abscesses, folliculitis, and pneumonias along with skeletal abnormalities. Careful history of susceptibility to skin and lung infections, thorough family history, and findings on physical exam can guide towards the diagnosis of this often-eluded condition. Early optimization of therapy with prophylactic antibiotics can prevent recurrent infections and future complications and improve quality of life and longevity of survival. We present a case of a young female with Hyper-IgE Syndrome with a novel mutation in STAT 3 gene who initially presented with long standing history of intractable skin abscesses being managed as Hidradenitis Suppurativa.

Interferon-gamma (IFN-γ): Exploring its implications in infectious diseases

A key player in driving cellular immunity, IFN-γ is capable of orchestrating numerous protective functions to heighten immune responses in infections and cancers. It can exhibit its immunomodulatory effects by enhancing antigen processing and presentation, increasing leukocyte trafficking, inducing an anti-viral state, boosting the anti-microbial functions and affecting cellular proliferation and apoptosis. A complex interplay between immune cell activity and IFN-γ through coordinated integration of signals from other pathways involving cytokines and Pattern Recognition Receptors (PRRs) such as Interleukin (IL)-4, TNF-α, Lipopolysaccharide (LPS), Type-I Interferons (IFNS) etc. leads to initiation of a cascade of pro-inflammatory responses. Microarray data has unraveled numerous genes whose transcriptional regulation is influenced by IFN-γ. Consequently, IFN-γ stimulated cells display altered expression of many such target genes which mediate its downstream effector functions. The importance of IFN-γ is further reinforced by the fact that mice possessing disruptions in the IFN-γ gene or its receptor develop extreme susceptibility to infectious diseases and rapidly succumb to them. In this review, we attempt to elucidate the biological functions and physiological importance of this versatile cytokine. The functional implications of its biological activity in several infectious diseases and autoimmune pathologies are also discussed. As a counter strategy, many virulent pathogenic species have devised ways to thwart IFN-γ endowed immune-protection. Thus, IFN-γ mediated host-pathogen interactions are critical for our understanding of disease mechanisms and these aspects also manifest enormous therapeutic importance for the annulment of various infections and autoimmune conditions.

Herpes Simplex Virus and Human Papillomavirus Coinfections in Hyperimmunoglobulin E Syndrome Presenting as a Conjunctival Mass Lesion

Hyperimmunoglobulin E syndrome (HIES) or Job's syndrome is a rare immunodeficiency disease with less than 200 cases reported worldwide, among which few cases are reported with lesions due to herpes simplex virus (HSV) or human papillomavirus (HPV). This case study presents a rare case of HIES with coinfection of HSV and HPV. A 12-year-old boy, previously diagnosed with HIES, presented with a large conjunctival mass lesion. The presence of HPV in the lesion was confirmed by biopsy and by using the line-probe assay method to detect the HPV genome. However, the mass lesion did not respond to anti-HPV therapy with topical interferon-α2b (IFN-α2b) and oral cimetidine but improved promptly after intravenous (IV) acyclovir, which is often administered for cutaneous herpetic lesions. This suggested the presence of HSV in the conjunctival mass. Review of pathology and HSV immunohistochemical staining confirmed the presence of HSV as a coinfection. The likelihood that the mass arose from an abnormal host response to HSV and HPV due to HIES was considered, but coexisting infection with these two viruses and HIES has not been reported in the literature; therefore, such cases require further investigation.