Bi-allelic variants in DNA mismatch repair proteins MutS Homolog MSH4 and MSH5 cause infertility in both sexes

STUDY QUESTION

Do bi-allelic variants in the genes encoding the MSH4/MSH5 heterodimer cause male infertility?

SUMMARY ANSWER

We detected biallelic, (likely) pathogenic variants in MSH5 (4 men) and MSH4 (3 men) in six azoospermic men, demonstrating that genetic variants in these genes are a relevant cause of male infertility.

WHAT IS KNOWN ALREADY

MSH4 and MSH5 form a heterodimer, which is required for prophase of meiosis I. One variant in MSH5 and two variants in MSH4 have been described as causal for premature ovarian insufficiency (POI) in a total of five women, resulting in infertility. Recently, pathogenic variants in MSH4 have been reported in infertile men. So far, no pathogenic variants in MSH5 had been described in males.

STUDY DESIGN, SIZE, DURATION

We utilized exome data from 1305 men included in the Male Reproductive Genomics (MERGE) study, including 90 males with meiotic arrest (MeiA). Independently, exome sequencing was performed in a man with MeiA from a large consanguineous family.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Assuming an autosomal-recessive mode of inheritance, we screened the exome data for rare, biallelic coding variants in MSH4 and MSH5. If possible, segregation analysis in the patients' families was performed. The functional consequences of identified loss-of-function (LoF) variants in MSH5 were studied using heterologous expression of the MSH5 protein in HEK293T cells. The point of arrest during meiosis was determined by γH2AX staining.

MAIN RESULTS AND THE ROLE OF CHANCE

We report for the first time (likely) pathogenic, homozygous variants in MSH5 causing infertility in 2 out of 90 men with MeiA and overall in 4 out of 902 azoospermic men. Additionally, we detected biallelic variants in MSH4 in two men with MeiA and in the sister of one proband with POI. γH2AX staining revealed an arrest in early prophase of meiosis I in individuals with pathogenic MSH4 or MSH5 variants. Heterologous in vitro expression of the detected LoF variants in MSH5 showed that the variant p.(Ala620GlnTer9) resulted in MSH5 protein truncation and the variant p.(Ser26GlnfsTer42) resulted in a complete loss of MSH5.

LARGE SCALE DATA

All variants have been submitted to ClinVar (SCV001468891-SCV001468896 and SCV001591030) and can also be accessed in the Male Fertility Gene Atlas (MFGA).

LIMITATIONS, REASONS FOR CAUTION

By selecting for variants in MSH4 and MSH5, we were able to determine the cause of infertility in six men and one woman, leaving most of the examined individuals without a causal diagnosis.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings have diagnostic value by increasing the number of genes associated with non-obstructive azoospermia with high clinical validity. The analysis of such genes has prognostic consequences for assessing whether men with azoospermia would benefit from a testicular biopsy. We also provide further evidence that MeiA in men and POI in women share the same genetic causes.

STUDY FUNDING/COMPETING INTEREST(S)

This study was carried out within the frame of the German Research Foundation sponsored Clinical Research Unit 'Male Germ Cells: from Genes to Function' (DFG, CRU326), and supported by institutional funding of the Research Institute Amsterdam Reproduction and Development and funds from the LucaBella Foundation. The authors declare no conflict of interest.

BSACI guideline for the diagnosis and management of allergic and non-allergic rhinitis (Revised Edition 2017; First edition 2007)

This is an updated guideline for the diagnosis and management of allergic and non-allergic rhinitis, first published in 2007. It was produced by the Standards of Care Committee of the British Society of Allergy and Clinical Immunology, using accredited methods. Allergic rhinitis is common and affects 10-15% of children and 26% of adults in the UK, it affects quality of life, school and work attendance, and is a risk factor for development of asthma. Allergic rhinitis is diagnosed by history and examination, supported by specific allergy tests. Topical nasal corticosteroids are the treatment of choice for moderate to severe disease. Combination therapy with intranasal corticosteroid plus intranasal antihistamine is more effective than either alone and provides second line treatment for those with rhinitis poorly controlled on monotherapy. Immunotherapy is highly effective when the specific allergen is the responsible driver for the symptoms. Treatment of rhinitis is associated with benefits for asthma. Non-allergic rhinitis also is a risk factor for the development of asthma and may be eosinophilic and steroid-responsive or neurogenic and non- inflammatory. Non-allergic rhinitis may be a presenting complaint for systemic disorders such as granulomatous or eosinophilic polyangiitis, and sarcoidoisis. Infective rhinitis can be caused by viruses, and less commonly by bacteria, fungi and protozoa.

BSACI guideline for the diagnosis and management of peanut and tree nut allergy

Peanut nut and tree nut allergy are characterised by IgE mediated reactions to nut proteins. Nut allergy is a global disease. Limited epidemiological data suggest varying prevalence in different geographical areas. Primary nut allergy affects over 2% of children and 0.5% of adults in the UK. Infants with severe eczema and/or egg allergy have a higher risk of peanut allergy. Primary nut allergy presents most commonly in the first five years of life, often after the first known ingestion with typical rapid onset IgE-mediated symptoms. The clinical diagnosis of primary nut allergy can be made by the combination of a typical clinical presentation and evidence of nut specifc IgE shown by a positive skin prick test (SPT) or specific IgE (sIgE) test. Pollen food syndrome is a distinct disorder, usually mild, with oral/pharyngeal symptoms, in the context of hay fever or pollen sensitisation, which can be triggered by nuts. It can usually be distinguish clinically from primary nut allergy. The magnitude of a SPT or sIgE relates to the probability of clinical allergy, but does not relate to clinical severity. SPT of ≥ 8 mm or sIgE ≥ 15 KU/L to peanut is highly predictive of clinical allergy. Cut off values are not available for tree nuts. Test results must be interpreted in the context of the clinical history. Diagnostic food challenges are usually not necessary but may be used to confirm or refute a conflicting history and test result. As nut allergy is likely to be a long-lived disease, nut avoidance advice is the cornerstone of management. Patients should be provided with a comprehensive management plan including avoidance advice, patient specific emergency medication and an emergency treatment plan and training in administration of emergency medication. Regular re-training is required.

Can we identify patients at risk of life-threatening allergic reactions to food?

Anaphylaxis has been defined as a 'severe, life-threatening generalized or systemic hypersensitivity reaction'. However, data indicate that the vast majority of food-triggered anaphylactic reactions are not life-threatening. Nonetheless, severe life-threatening reactions do occur and are unpredictable. We discuss the concepts surrounding perceptions of severe, life-threatening allergic reactions to food by different stakeholders, with particular reference to the inclusion of clinical severity as a factor in allergy and allergen risk management. We review the evidence regarding factors that might be used to identify those at most risk of severe allergic reactions to food, and the consequences of misinformation in this regard. For example, a significant proportion of food-allergic children also have asthma, yet almost none will experience a fatal food-allergic reaction; asthma is not, in itself, a strong predictor for fatal anaphylaxis. The relationship between dose of allergen exposure and symptom severity is unclear. While dose appears to be a risk factor in at least a subgroup of patients, studies report that individuals with prior anaphylaxis do not have a lower eliciting dose than those reporting previous mild reactions. It is therefore important to consider severity and sensitivity as separate factors, as a highly sensitive individual will not necessarily experience severe symptoms during an allergic reaction. We identify the knowledge gaps that need to be addressed to improve our ability to better identify those most at risk of severe food-induced allergic reactions.

BSACI guideline for the management of chronic urticaria and angioedema

This guidance for the management of patients with chronic urticaria and angioedema has been prepared by the Standards of Care Committee of the British Society for Allergy and Clinical Immunology (BSACI). The guideline is based on evidence as well as on expert opinion and is aimed at both adult physicians and paediatricians practising in allergy. The recommendations are evidence graded. During the development of these guidelines, all BSACI members were included in the consultation process using a Web-based system. Their comments and suggestions were carefully considered by the Standards of Care Committee. Where evidence was lacking, a consensus was reached by the experts on the committee. Included in this management guideline are clinical classification, aetiology, diagnosis, investigations, treatment guidance with special sections on children with urticaria and the use of antihistamines in women who are pregnant or breastfeeding. Finally, we have made recommendations for potential areas of future research.

Management of allergy to penicillins and other beta-lactams

The Standards of Care Committee of the British Society for Allergy and Clinical Immunology (BSACI) and an expert panel have prepared this guidance for the management of immediate and non-immediate allergic reactions to penicillins and other beta-lactams. The guideline is intended for UK specialists in both adult and paediatric allergy and for other clinicians practising allergy in secondary and tertiary care. The recommendations are evidence based, but where evidence is lacking, the panel reached consensus. During the development of the guideline, all BSACI members were consulted using a Web-based process and all comments carefully considered. Included in the guideline are epidemiology of allergic reactions to beta-lactams, molecular structure, formulations available in the UK and a description of known beta-lactam antigenic determinants. Sections on the value and limitations of clinical history, skin testing and laboratory investigations for both penicillins and cephalosporins are included. Cross-reactivity between penicillins and cephalosporins is discussed in detail. Recommendations on oral provocation and desensitization procedures have been made. Guidance for beta-lactam allergy in children is given in a separate section. An algorithm to help the clinician in the diagnosis of patients with a history of penicillin allergy has also been included.

BSACI guideline for the diagnosis and management of cow's milk allergy

This guideline advises on the management of patients with cow's milk allergy. Cow's milk allergy presents in the first year of life with estimated population prevalence between 2% and 3%. The clinical manifestations of cow's milk allergy are very variable in type and severity making it the most difficult food allergy to diagnose. A careful age- and disease-specific history with relevant allergy tests including detection of milk-specific IgE (by skin prick test or serum assay), diagnostic elimination diet, and oral challenge will aid in diagnosis in most cases. Treatment is advice on cow's milk avoidance and suitable substitute milks. Cow's milk allergy often resolves. Reintroduction can be achieved by the graded exposure, either at home or supervised in hospital depending on severity, using a milk ladder. Where cow's milk allergy persists, novel treatment options may include oral tolerance induction, although most authors do not currently recommend it for routine clinical practice. Cow's milk allergy must be distinguished from primary lactose intolerance. This guideline was prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI) and is intended for clinicians in secondary and tertiary care. The recommendations are evidence based, but where evidence is lacking the panel of experts in the committee reached consensus. Grades of recommendation are shown throughout. The document encompasses epidemiology, natural history, clinical presentations, diagnosis, and treatment.

Anaphylaxis: guidelines from the European Academy of Allergy and Clinical Immunology

Anaphylaxis is a clinical emergency, and all healthcare professionals should be familiar with its recognition and acute and ongoing management. These guidelines have been prepared by the European Academy of Allergy and Clinical Immunology (EAACI) Taskforce on Anaphylaxis. They aim to provide evidence-based recommendations for the recognition, risk factor assessment, and the management of patients who are at risk of, are experiencing, or have experienced anaphylaxis. While the primary audience is allergists, these guidelines are also relevant to all other healthcare professionals. The development of these guidelines has been underpinned by two systematic reviews of the literature, both on the epidemiology and on clinical management of anaphylaxis. Anaphylaxis is a potentially life-threatening condition whose clinical diagnosis is based on recognition of a constellation of presenting features. First-line treatment for anaphylaxis is intramuscular adrenaline. Useful second-line interventions may include removing the trigger where possible, calling for help, correct positioning of the patient, high-flow oxygen, intravenous fluids, inhaled short-acting bronchodilators, and nebulized adrenaline. Discharge arrangements should involve an assessment of the risk of further reactions, a management plan with an anaphylaxis emergency action plan, and, where appropriate, prescribing an adrenaline auto-injector. If an adrenaline auto-injector is prescribed, education on when and how to use the device should be provided. Specialist follow-up is essential to investigate possible triggers, to perform a comprehensive risk assessment, and to prevent future episodes by developing personalized risk reduction strategies including, where possible, commencing allergen immunotherapy. Training for the patient and all caregivers is essential. There are still many gaps in the evidence base for anaphylaxis.

British Society for Allergy and Clinical Immunology guidelines for the management of egg allergy

This guideline advises on the management of patients with egg allergy. Most commonly, egg allergy presents in infancy, with a prevalence of approximately 2% in children and 0.1% in adults. A clear clinical history and the detection of egg white-specific IgE (by skin prick test or serum assay) will confirm the diagnosis in most cases. Egg avoidance advice is the cornerstone of management. Egg allergy often resolves and re-introduction can be achieved at home if reactions have been mild and there is no asthma. Patients with a history of severe reactions or asthma should have reintroduction guided by a specialist. All children with egg allergy should receive measles, mumps and rubella (MMR) vaccination. Influenza and yellow fever vaccines should only be considered in egg-allergic patients under the guidance of an allergy specialist. This guideline was prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI) and is intended for allergists and others with a special interest in allergy. The recommendations are evidence-based but where evidence was lacking consensus was reached by the panel of specialists on the committee. The document encompasses epidemiology, risk factors, diagnosis, treatment, prognosis and co-morbid associations.

Successful oral tolerance induction in severe peanut allergy

BACKGROUND

Peanut allergy is common, potentially severe and rarely resolves causing impaired quality of life. No disease-modifying treatment exists and there is therefore a need to develop a therapeutic intervention.

AIMS OF THE STUDY

The aim of this study was to investigate whether peanut oral immunotherapy (OIT) can induce clinical tolerance to peanut protein.

METHODS

Four peanut-allergic children underwent OIT. Preintervention oral challenges were performed to confirm clinical allergy and define the amount of protein required to cause a reaction (dose thresholds). OIT was then administered as daily doses of peanut flour increasing from 5 to 800 mg of protein with 2-weekly dose increases. After 6 further weeks of treatment, the oral challenge was repeated to define change in dose threshold and subjects continued daily treatment.

RESULTS

Preintervention challenges confirmed peanut allergy and revealed dose thresholds of 5-50 mg (1/40-1/4 of a whole peanut); one subject had anaphylaxis during challenge and required adrenaline injection. All subjects tolerated immunotherapy updosing to 800 mg protein and i.m. adrenaline was not required. Each subject tolerated at least 10 whole peanuts (approximately 2.38 g protein) in postintervention challenges, an increase in dose threshold of at least 48-, 49-, 55- and 478-fold for the four subjects.

CONCLUSIONS

We demonstrated a substantial increase in dose threshold after OIT in all subjects, including the subject with proven anaphylaxis. OIT was well tolerated and conferred protection against at least 10 peanuts, more than is likely to be encountered during accidental ingestion.

Enhanced imaging in low dose electron microscopy using electron counting

We compare the direct electron imaging performance at 120keV of a monolithic active pixel sensor (MAPS) operated in a conventional integrating mode with the performance obtained when operated in a single event counting mode. For the combination of sensor and incident electron energy used here, we propose a heuristic approach with which to process the single event images in which each event is renormalised to have an integrated weight of unity. Using this approach we find enhancements in the Nyquist frequency modulation transfer function (MTF) and detective quantum efficiency (DQE) over the corresponding integrating mode values by factors of 8 and 3, respectively.

BSACI guidelines for the management of allergic and non-allergic rhinitis

This guidance for the management of patients with allergic and non‐allergic rhinitis has been prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI). The guideline is based on evidence as well as on expert opinion and is for use by both adult physicians and paediatricians practicing in allergy. The recommendations are evidence graded. During the development of these guidelines, all BSACI members were included in the consultation process using a web‐based system. Their comments and suggestions were carefully considered by the SOCC. Where evidence was lacking, consensus was reached by the experts on the committee. Included in this guideline are clinical classification of rhinitis, aetiology, diagnosis, investigations and management including subcutaneous and sublingual immunotherapy. There are also special sections for children, co‐morbid associations and pregnancy. Finally, we have made recommendations for potential areas of future research.

T cell proliferation and cytokine responses to ovalbumin and ovomucoid detected in children with and without egg allergy

BACKGROUND

The specific T cell responses in egg allergy and resolution have not been fully elucidated.

OBJECTIVE

To characterize egg allergen-specific T cells of children with active and resolved egg allergy, in comparison with non-allergic controls.

METHOD

We studied children with active (n=35) or resolved (n=20) egg allergy determined by oral challenge, and non-allergic controls (n=15). Peripheral blood mononuclear cells were labelled with carboxyfluorescein succinimidyl ester (CFSE) and stimulated with ovalbumin (OVA), ovomucoid (OM) or tetanus toxoid. Flow cytometry was used to detect divided CD3+ CFSE(lo) cells that expressed intra-cytoplasmic IL-4 or IFN-gamma. The cell division index (CDI) was calculated as a measure of allergen-specific proliferation. Peanut-specific T cells of a subgroup of children who also had peanut allergy were also studied.

RESULTS

OVA-specific T cells were found in subjects with active (87%) or resolved (75%) egg allergy and in controls (67%), with a trend towards increased T cell proliferation in allergy. OM-induced weaker T cell responses than OVA, stimulating fewer responders (46% allergic, 50% resolved, 60% controls) and 10-fold less proliferation [CDI(OVA) 2.0 (median), 25.6 (maximum) vs. CDI(OM) 0.2 (median), 15.1 (maximum); P<0.01]. Both egg allergens induced significant IL-4+ (median 10%, range 1.4-58%) and IFN-gamma+ (median 28%, range 4.5-63%) cells in responders, including non-allergics. There were no significant differences in IFN-gamma+ or IL-4+ cells or in IFN-gamma/IL-4 ratios between groups. Peanut-specific T cell proliferation was significantly higher in peanut allergy [CDI(CPE) 16.5 (median), 24.8 (maximum)] compared with controls [CDI(CPE) 2.1 (median), 16.1 (maximum)] but cytokine profiles were not different. Tetanus-specific T cells were seen in 90% of the subjects, with no significant inter-group differences in responses.

CONCLUSION

Egg allergen-specific T cells are readily detected in all groups and not restricted to egg allergy. In contrast, peanut-specific proliferation was significantly higher in peanut allergy. This suggests that T cell responses in peanut and egg allergy may differ. We did not find T helper type 2-deviated cytokine responses in egg or peanut allergy.

Patterns of immunoglobulin G responses to egg and peanut allergens are distinct: ovalbumin-specific immunoglobulin responses are ubiquitous, but peanut-specific immunoglobulin responses are up-regulated in peanut allergy

BACKGROUND

The clinical significance of food-specific IgG subclasses in food allergy and tolerance remains unclear. Specific IgG titres are often reported in non-standardized units, which do not allow comparisons between studies or allergens.

OBJECTIVE

To quantify, in absolute units, ovalbumin (OVA)- and peanut-specific IgG levels in children with peanut or egg allergy (active or resolved) and in non-allergic controls. Methods Children aged 1-15 years were recruited. Peanut allergy was diagnosed by convincing history and a 95% predictive level of specific IgE; egg allergy or resolution was confirmed by oral challenge. Serum IgG, IgG1 and IgG4 levels (microg/mL) to OVA and peanut extract were quantified by ELISA.

RESULTS

OVA- and peanut-specific IgG was detected in all subjects. In non-allergic controls (n=18), OVA-specific IgG levels were significantly higher than peanut-specific IgG (median microg/mL IgG=15.9 vs. 2.2, IgG1=1.3 vs. 0.6, IgG4=7.9 vs. 0.7; P<0.01). There were no differences in OVA-specific IgG, IgG1 and IgG4 between egg-allergic (n=40), egg-resolved (n=22) and control (n=18) subjects. In contrast, peanut-specific IgG (median microg/mL IgG=17.0, IgG1=3.3, IgG4=5.2) were significantly higher in peanut-allergic subjects (n=59) compared with controls and with non-peanut-sensitized but egg-allergic subjects (n=26). Overall, the range of IgG4 was greater than IgG1, and IgG4 was the dominant subclass in >60% of all subjects.

CONCLUSION

OVA-specific IgG levels of egg-allergic, egg-resolved or control groups are not distinguishable. Higher peanut-specific IgG levels are associated with clinical allergy, but the range of IgG titres of the allergic and control groups overlapped. Hence, OVA and peanut-specific IgG measurements do not appear to be of diagnostic value. Strong IgG responses to OVA may be a normal physiological response to a protein frequently ingested from infancy, whereas up-regulated IgG responses in peanut allergy may be indicative of a dysregulated immune response to peanut allergens.

Cashew nut causes more severe reactions than peanut: case-matched comparison in 141 children

BACKGROUND

Cashew nut allergy is becoming common, but the risk of severe reactions in comparison with peanut allergy is unknown.

METHOD

A case-matching study of children with a recent history of a reaction after definite nut ingestion, with positive skin prick test. Children whose worst ever reaction was to cashew nut (cashew group), were matched with two children each whose worst ever reaction was to peanut (peanut group) for sex, age of reaction and presentation, amount ingested, and asthma. Severity of the worst clinical reactions to date was compared.

RESULTS

A total of 47 children in the cashew group were matched to 94 in the peanut group. There were no differences in clinical features between groups for matching criteria, except asthma (more prevalent in the peanut group). Wheezing and cardiovascular symptoms were reported more frequently during reactions in the cashew compared with the peanut group: odds ratios (OR) 8.4 (95% CI: 3.2-22.0) and 13.6 (95% CI: 5.6-32.8), respectively. The cashew group received intramuscular adrenaline more frequently: OR 13.3 (95% CI: 5.5-32.2). Overall, the OR for a severe reaction (severe dyspnoea and/or collapse) in the cashew group was 25.1 (95% CI: 3.1-203.5).

CONCLUSIONS

Previous studies show cashew nut can cause severe reactions; this is the first study to show by case-matching that severe clinical reactions occur more frequently in cashew compared with peanut allergy. The nut type which caused the worst reaction to date should be considered when providing emergency medication.

Facial thermography is a sensitive and specific method for assessing food challenge outcome

BACKGROUND

Oral challenge is widely used for diagnosing food allergy but variable interpretation of subjective symptoms may cause error. Facial thermography was evaluated as a novel, objective and sensitive indicator of challenge outcome.

METHODS

A total of 24 children with a history of egg allergy underwent oral challenge, which were scored positive when objective symptoms occurred or negative after all doses were consumed without reaction. Facial temperatures were recorded at baseline and 10-min intervals. The difference between mean and baseline temperature (DeltaT), maximum DeltaT during challenge (DeltaT(max)) and area under curve of DeltaT against time (DeltaTAUC) were calculated for predefined nasal, oral and forehead areas, and related to objective challenge outcome.

RESULTS

There were 13 positive and 11 negative challenges. Median nasal DeltaTAUC and DeltaT(max) were greater in positive compared with negative challenges (231- and 5-fold, respectively; P < 0.05). In positive challenges, nasal temperatures showed an early transient rise at 20 min, preceding objective symptoms at median 67 min. There was a sustained temperature increase from 60 min, which was reduced by antihistamines. A cut-off for nasal DeltaT(max) of 0.8 degrees C occurring within 20 min of the start of the challenge predicted outcome with 91% sensitivity (positive predictive value [PPV] 100%) and 100% specificity (negative predictive value [NPV] 93%). Subjective symptoms occurred in four of 13 positive and three of 11 negative challenges.

CONCLUSIONS

Facial thermography consistently detects a significant early rise in nasal temperature during positive compared with negative food challenges, which is evident before objective symptoms occur. Thermography may therefore provide a sensitive method to determine outcome of food challenges and investigate the pathophysiology of food allergic reactions.

BSACI guidelines for the management of chronic urticaria and angio-oedema

This guidance for the management of patients with chronic urticaria and angio-oedema has been prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI). The guideline is based on evidence as well as on expert opinion and is aimed at both adult physicians and paediatricians practising in allergy. The recommendations are evidence graded. During the development of these guidelines, all BSACI members were included in the consultation process using a web-based system. Their comments and suggestions were carefully considered by the SOCC. Where evidence was lacking a consensus was reached by the experts on the committee. Included in this guideline are clinical classification, aetiology, diagnosis, investigations, treatment guidance with special sections on children with urticaria, and the use of antihistamines in women who are pregnant or breastfeeding. Finally, we have made recommendations for potential areas of future research.

Efficacy of a management plan based on severity assessment in longitudinal and case-controlled studies of 747 children with nut allergy: proposal for good practice

BACKGROUND

There are few data on the long-term management of children with peanut/nut allergy. Advice is variable and often inadequate; further reactions are common. There is no consensus on the criteria for prescription of rescue medication, particularly adrenaline.

METHOD

A longitudinal prospective and case-control study in a tertiary allergy clinic. Patients/parents/school staff of 747 children with confirmed peanut or tree nut allergy received detailed verbal and written advice on nut avoidance, training in recognition and (self-) treatment of reactions and a written treatment plan. The severity of nut allergy was graded (mild-severe) and emergency medication was allocated according to our criteria: all received oral antihistamines, injected adrenaline (EpiPen) was given to those with reactions with airway narrowing, milder reactions to low-dose exposure or concomitant asthma. At annual follow-up over 25 906 patient-months (median: 39 months) retraining was given and details of further reactions (frequency, severity and treatment) were obtained. Criteria for allocation of EpiPen were evaluated.

RESULTS

The worst reaction pre-enrolment was mild in 64% and moderate/severe in 36% (airway narrowing). Of 615 subjects followed up, 21% had a further reaction (eightfold reduction in frequency), mostly mild. There was a 60-fold reduction in the frequency of severe reactions. Of those with a moderate-severe initial reaction, 99.5% had no or a less severe follow-up reaction. No child with a mild or severe index reaction had a severe follow-up reaction. Only 1/615 (0.2%) had a severe follow-up reaction and only 2/615 (0.3%) used adrenaline, both successfully and had it available according to our criteria. Of mild-moderate reactions, 77% required oral antihistamines alone and 15% no treatment. Children who had follow-up reactions had more frequent and severe reactions pre-enrolment.

CONCLUSION

The management plan greatly reduced the frequency and severity of further reactions and was successful for all children. Our criteria for selective prescription of EpiPen in the context of this management plan were appropriate. This is the first study to provide evidence on which to inform practice.

Interpretation of tests for nut allergy in one thousand patients, in relation to allergy or tolerance

BACKGROUND

Peanut and tree nut allergy are common, increasing in prevalence and the commonest food cause of anaphylaxis. In the USA, 7.8% are sensitized (have nut-specific IgE), but not all those sensitized are allergic. Lack of data makes interpretation of tests for nut-specific IgE difficult.

OBJECTIVES

This is the first study to investigate the clinical significance of test results for peanut and tree nut allergy in allergic or tolerant patients. Findings are related to the severity of the allergy.

METHOD

An observational study of 1000 children and adults allergic to at least one nut. History of reactions (severity graded) or tolerance to up to five nuts was obtained and skin prick test (SPT)/serum-specific IgE (CAP) performed.

RESULTS

There was no correlation between SPT size and graded severity of worst reaction for all nuts combined or for peanut, hazelnut, almond and walnut. For CAP, there was no correlation for all nuts. Where patients tolerated a nut, 43% had positive SPT of 3-7 mm and 3% > or = 8 mm. For CAP, 35% were positive (0.35-14.99 kU/L) and 5% > or = 15 kU/L. In SPT range 3-7 mm, 54% were allergic and 46% were tolerant. There was poor concordance between SPT and CAP (66%). Of patients with a clear nut-allergic history, only 0.5% had negative SPT, but 22% negative CAP.

CONCLUSIONS

Magnitude of SPT or CAP does not predict clinical severity, with no difference between minor urticaria and anaphylaxis. SPT is more reliable than CAP in confirming allergy. Forty-six per cent of those tolerant to a nut have positive tests > or = 3 mm (sensitized but not allergic). One cannot predict clinical reactivity from results in a wide 'grey area' of SPT 3-7 mm; 22% of negative CAPs are falsely reassuring and 40% of positive CAPs are misleading. This emphasizes the importance of the history. Understanding this is essential for accurate diagnosis. Patients with SPT > or = 8 mm and CAP > or = 15 kU/L were rarely tolerant so these levels are almost always (in > or = 95%) diagnostic.

Expression of bone morphogenetic protein receptors in the developing mouse metanephros

While bone morphogenetic proteins (BMPs) 2, 4 and 7 have recently been implicated in aspects of metanephric development, and expression patterns of these ligands have been described in the developing metanephros, the distribution of BMP receptors in developing metanephroi remains unknown. In the present study, in situ hybridisation histochemistry was used to localise mRNAs for BMP type-I receptors (BMPR-IA and BMPR-IB) and the BMP type-II receptor (BMPR-II) in developing mouse metanephroi. At embryonic day 12.5 (E12.5) and E14.5 transcripts for BMP type-I receptors were localised to the tips and body of the branching ureter as well as mesenchymal condensates, developing vesicles and comma-shaped bodies. Localisation of BMPR-II transcripts was similar although expression was not observed in the body of the ureter. At E17.5, transcripts for all three receptors were localised in the nephrogenic zone including ureteric tips, vesicles, comma- and S-shaped bodies as well the body of the ureter and in tubules. BMP type-I and type-II receptor transcripts co-localised with each other, in agreement with the well-documented evidence that BMPs signal via heterotetrameric complexes of type-I and type-II receptors and with the previously reported metanephric expression pattern of BMPs. These patterns of receptor expression suggest that these molecules are important regulators of epithelial-mesenchymal interactions, nephron development and ureteric branching morphogenesis.

In vitro studies on the roles of transforming growth factor-beta 1 in rat metanephric development

BACKGROUND

The development of the permanent kidney (metanephros) involves the interplay between both positive and negative regulatory molecules. Transforming growth factor-beta1 (TGF-beta 1) has previously been shown to negatively regulate ureteric duct growth. However, its potential role in nephron development and glomerulogenesis has been largely ignored.

METHODS

In situ hybridization and reverse transcription-polymerase chain reaction were employed to examine the temporal and spatial localization of TGF-beta 1 mRNA and a TGF-beta type I receptor (activin-like receptor kinase-5; ALK-5) mRNA in developing rat metanephroi. The addition of exogenous TGF-beta 1 to rat metanephric organ culture at different time points was used to examine the role of TGF-beta 1 in ureteric duct growth and nephron development.

RESULTS

TGF-beta 1 mRNA did not colocalize with ALK-5 mRNA. Instead, TGF-beta1 mRNA colocalized with the TGF-beta type II receptor mRNA. The addition of recombinant human TGF-beta 1 to rat metanephric organ culture at the beginning of the culture period inhibited total metanephric growth and the growth of the ureteric tree, resulting in a decrease in nephron number. Similarly, the addition of TGF-beta 1 to metanephroi after 48 hours of culture inhibited ureteric duct growth, decreasing nephron number. The addition of TGF-beta 1 at days 0 or 2 of culture promoted hypertrophy of the renal capsule.

CONCLUSIONS

These findings confirm that TGF-beta 1 inhibits ureteric duct growth and thereby nephron endowment in developing rat metanephroi in vitro. However, TGF-beta 1 does not appear to play a significant role in nephron development per se once the epithelial vesicle has formed.

Long-term prospective observational study of patients with peanut and nut allergy after participation in a management plan

BACKGROUND

Peanut and nut allergy is common and the most frequent cause of severe or fatal reactions to foods. Current advice is poor--doctors give an epinephrine injector to patients, without training or advice on nut avoidance--so that further reactions are common and deaths occur. We devised and assessed a management programme providing advice on nut avoidance and emergency medication.

METHODS

Unselected referrals with confirmed peanut or tree-nut allergy were recruited. Severity of nut allergy was graded 1-5 and emergency medication allocated accordingly: oral antihistamine with or without inhaled or injected epinephrine. Patients, parents, and school staff received verbal and written advice on nut avoidance as well as training in recognition and self-treatment of reactions, with a written treatment plan. At follow-up (more than 13610 patient months) retraining was given and details of further reactions obtained.

FINDINGS

88 (15%) of 567 patients had a follow-up reaction of reduced severity. 62 of 88 were mild (grades 1-3, mainly cutaneous) and 49 patients used oral antihistamine, six inhaled adrenaline, and ten took no treatment. 12 of 12 patients with a moderate follow-up reaction improved after inhaled epinephrine. Only three (0.5%) of 567 patients, aged 27-40 years, had a severe follow-up reaction (involving dyspnoea) compared with 12% initially. Only one of 567 changed from a mild index reaction to a severe follow-up reaction. Patients with a moderate/severe (grade 4-5) reaction were older (median 18 years vs 9 years; p=0.03) and nine of 26 received injected epinephrine which was always effective. 85% of patients had no further reactions. Severity was related to the amount of nut eaten.

INTERPRETATION

Self-treatment was effective (inhaled epinephrine for early laryngeal oedema and an epinephrine injector for severe reactions) but provision of this treatment, including who should carry epinephrine, required assessment of allergy severity. Our management plan was effective, and our results indicate that patients should be referred to specialist allergy centres for advice on nut avoidance.

Comparison of recombinant growth differentiation factor-9 and oocyte regulation of KIT ligand messenger ribonucleic acid expression in mouse ovarian follicles

Oocytes secrete factors that regulate the development of the surrounding granulosa cells in ovarian follicles. KIT ligand (KL) mRNA expression in granulosa cells is thought to be regulated by oocytes; however, the factor(s) that mediate this effect are not known. One candidate is the oocyte-specific gene product growth differentiation factor-9 (GDF-9). This study examined the effect of recombinant GDF-9 (rGDF-9) on steady-state KL mRNA expression levels in preantral and mural granulosa cells in vitro. Furthermore, the study compared the effect of rGDF-9 with that of coculture with oocytes at different developmental stages. As determined by RNase protection assay, both KL-1 and KL-2 mRNA levels in preantral and mural granulosa cells were suppressed by 25-250 ng/ml rGDF-9. Fully grown oocytes also suppressed both KL-1 and KL-2 mRNA expression levels. Partly grown oocytes isolated from 7-, 10-, or 12-day-old mice either had no effect on KL mRNA levels or promoted KL-1 mRNA steady-state expression. It is concluded that GDF-9 is likely to mediate the action of fully grown, but not partly grown, oocytes on granulosa cell KL mRNA expression.

Advances in renal development

Branching morphogenesis, mesenchymal cell condensation and mesenchymal-to-epithelial conversion are key steps in kidney development and morphogenesis of several other organs. Review articles describing our current knowledge of the genetic and molecular regulation of these processes have been published. Therefore, this review focuses on the important question of cell lineage specification during kidney development. We describe how new insights are being made into the specification of kidney cells in the intermediate mesoderm, as well as specification of cells that will form the renal mesenchyme, ureteric duct, nephron tubule epithelium and renal vasculature.

Paracrine actions of growth differentiation factor-9 in the mammalian ovary

Although the transforming growth factor-beta (TGF-beta) superfamily is the largest family of secreted growth factors, surprisingly few downstream target genes in their signaling pathways have been identified. Likewise, the identities of oocyte-derived secreted factors, which regulate important oocyte-somatic cell interactions, remain largely unknown. For example, oocytes are known to secrete paracrine growth factor(s) which are necessary for cumulus expansion, induction of hyaluronic acid synthesis, and suppression of LH receptor (LHR) mRNA synthesis. Our previous studies demonstrated that absence of the TGF-beta family member, growth differentiation factor-9 (GDF-9), blocks ovarian folliculogenesis at the primary follicle stage leading to infertility. In the present study, we demonstrate that mouse GDF-9 protein is expressed in all oocytes beginning at the type 3a follicle stage including antral follicles. To explore the biological functions of GDF-9 in the later stages of folliculogenesis and cumulus expansion, we produced mature, glycosylated, recombinant mouse GDF-9 using a Chinese hamster ovary cell expression system. A granulosa cell culture system was established to determine the role of GDF-9 in the regulation of several key ovarian gene products using semiquantitative RT-PCR. We find that recombinant GDF-9 induces hyaluronan synthase 2 (HAS2), cyclooxygenase 2 (COX-2), and steroidogenic acute regulator protein (StAR) mRNA synthesis but suppresses urokinase plasminogen activator (uPA) and LHR mRNA synthesis. Consistent with the induction of StAR mRNA by GDF-9, recombinant GDF-9 increases granulosa cell progesterone synthesis in the absence of FSH. Since induction of HAS2 and suppression of the protease uPA in cumulus cells are key events in the production of the hyaluronic acid-rich extracellular matrix which is produced during cumulus expansion, we determined whether GDF-9 could mimic this process. Using oocytectomized cumulus cell-oocyte complexes, we show that recombinant GDF-9 induces cumulus expansion in vitro. These studies demonstrate that GDF-9 can bind to receptors on granulosa cells to regulate the expression of a number of gene products. Thus, in addition to playing a critical function as a growth and differentiation factor during early folliculogenesis, GDF-9 functions as an oocyte-secreted paracrine factor to regulate several key granulosa cell enzymes involved in cumulus expansion and maintenance of an optimal oocyte microenvironment, processes which are essential for normal ovulation, fertilization, and female reproduction.

Molecular regulation of nephron endowment

Recent data suggests that the number of nephrons in normal adult human kidneys ranges from approximately 300,000 to more than 1 million. There is increasing evidence that reduced nephron number, either inherited or acquired, is associated with the development of essential hypertension, chronic renal failure, renal disease in transitional indigenous populations, and possibly the long-term success of renal allografts. Three processes ultimately govern the number of nephrons formed during the development of the permanent kidney (metanephros): branching of the ureteric duct in the metanephric mesenchyme; condensation of mesenchymal cells at the tips of the ureteric branches; and conversion of the mesenchymal condensates into epithelium. This epithelium then grows and differentiates to form nephrons. In recent years, we have learned a great deal about the molecular regulation of these three central processes and hence the molecular regulation of nephron endowment. Data has come from studies on cell lines, isolated ureteric duct epithelial cells, isolated metanephric mesenchyme, and whole metanephric organ culture, as well as from studies of heterozygous and homozygous null mutant mice. With accurate and precise methods now available for estimating the total number of nephrons in kidneys, more advances in our understanding of the molecular regulation of nephron endowment can be expected in the near future.

Maternal side effects of prenatal dexamethasone therapy for fetal congenital adrenal hyperplasia

Prenatal treatment of virilizing congenital adrenal hyperplasia in female fetuses via maternal dexamethasone (Dex) therapy (1-1.5 mg/day) from first trimester to birth was associated with excessive weight gain (47-56 pounds at 35-37 weeks gestation), Cushingoid facial features, severe striae resulting in permanent scarring, and hyperglycemic response (8-11.7 nmol/L) to oral glucose administration in all our experience (three cases). Other symptoms included hypertension, gastrointestinal intolerance, or extreme irritability. Previous pregnancies were uncomplicated by these problems. In each case, first or second trimester amniotic fluid 17-hydroxyprogesterone (17OHP, 17-41 nmol/L; normal less than 0.4 nmol/L), androstenedione (22-31 nmol/L, normal less than 5 nmol/L), and testosterone levels (0.54-0.7 nmol/L, normal less than 0.4 nmol/L) during Dex treatment were elevated regardless of the newborn genital outcome. Maternal serum estriol (E3) levels in one mother (normal newborn genitalia) were consistently low (less than 0.2 nmol/L) during the second and third trimester. In two mothers (partially virilized newborn genitalia) initial second trimester E3 levels were unsuppressed (11, 17.4 nmol/L) and suppressed (less than 1.4 nmol/L) following short-term increased dose.

CONCLUSION

prenatal Dex treatment of virilizing congenital adrenal hyperplasia at a dose of 1-1.5 mg daily throughout gestation is associated with significant maternal side effects. Parents should be informed of these side effects before initiation of treatment. Careful monitoring for signs of side effects, medical intervention when necessary, and lowering of Dex dose during the second half of gestation would minimize the side effects. Maternal serum E3 levels appear useful for prediction of fetal outcome while amniotic fluid steroid levels may not.

3 alpha-Androstanediol glucuronide in premature and normal pubarche

To investigate the role of adrenal androgens in 3 alpha-androstanediol glucuronide (3AG) production in childhood, we compared serum 3AG and androgen levels [dehydroepiandrosterone (DHEA), DHEA sulfate (DS), androstenedione (delta 4-A), and testosterone (T)] in 32 children with premature pubarche due to idiopathic premature adrenarche (IPA; n = 26), partial 21-hydroxylase deficiency (n = 2), or 3 beta-hydroxysteroid dehydrogenase deficiency (n = 4) with those in 36 normal prepubertal (18 males and 18 females) and 22 normal pubertal Tanner II-III subjects (10 males and 12 females). Serum 3AG (2.7 +/- 2.0 nmol/L) and all androgen concentrations in children with IPA were significantly higher (P less than 0.05-0.001) than those in normal prepubertal children (3AG, 0.8 +/- 0.5 nmol/L). Serum 3AG and androgen levels, except T, in all children with premature pubarche due to 21-hydroxylase deficiency or 3 beta-hydroxysteroid dehydrogenase deficiency were higher than those in the normal prepubertal children. Serum 3AG and all androgen levels in normal Tanner II-III male (3AG, 3.8 +/- 1.7 nmol/L) or female (3AG, 1.74 +/- 0.52 nmol/L) subjects were also significantly higher (P less than 0.05-0.001) than those in prepubertal children. Serum 3AG, DHEA, DS, and delta 4-A levels in children with IPA were similar to those in normal Tanner II-III females or males, but serum T in children with IPA (0.37 +/- 0.2 nmol/L) was significantly lower (P less than 0.05-0.001) than that in normal pubertal females (0.71 +/- 0.37 nmol/L) or males (4.5 +/- 2.6 nmol/L). In the combined group (n = 88), 3AG levels correlated better with serum DS (r = 0.7), DHEA (r = 0.6), and delta 4-A (r = 0.52), than with T (r = 0.31) levels. These data suggest that the weak adrenal androgens DS, DHEA, and delta 4-A contribute substantially to 3AG production in premature and normal pubarche.