Biallelic deleterious germline SH2B3 variants cause a novel syndrome of myeloproliferation and multi-organ autoimmunity

SH2B3 is a negative regulator of multiple cytokine receptor signalling pathways in haematopoietic tissue. To date, a single kindred has been described with germline biallelic loss-of-function SH2B3 variants characterized by early onset developmental delay, hepatosplenomegaly and autoimmune thyroiditis/hepatitis. Herein, we described two further unrelated kindreds with germline biallelic loss-of-function SH2B3 variants that show striking phenotypic similarity to each other as well as to the previous kindred of myeloproliferation and multi-organ autoimmunity. One proband also suffered severe thrombotic complications. CRISPR-Cas9 gene editing of zebrafish sh2b3 created assorted deleterious variants in F0 crispants, which manifest significantly increased number of macrophages and thrombocytes, partially replicating the human phenotype. Treatment of the sh2b3 crispant fish with ruxolitinib intercepted this myeloproliferative phenotype. Skin-derived fibroblasts from one patient demonstrated increased phosphorylation of JAK2 and STAT5 after stimulation with IL-3, GH, GM-CSF and EPO compared to healthy controls. In conclusion, these additional probands and functional data in combination with the previous kindred provide sufficient evidence for biallelic homozygous deleterious variants in SH2B3 to be considered a valid gene-disease association for a clinical syndrome of bone marrow myeloproliferation and multi-organ autoimmune manifestations.

A novel cause of DKC1-related bone marrow failure: Partial deletion of the 3' untranslated region

Telomere biology disorders (TBDs), including dyskeratosis congenita (DC), are a group of rare inherited diseases characterized by very short telomeres. Mutations in the components of the enzyme telomerase can lead to insufficient telomere maintenance in hematopoietic stem cells, resulting in the bone marrow failure that is characteristic of these disorders. While an increasing number of genes are being linked to TBDs, the causative mutation remains unidentified in 30‐40% of patients with DC. There is therefore a need for whole genome sequencing (WGS) in these families to identify novel genes, or mutations in regulatory regions of known disease‐causing genes. Here we describe a family in which a partial deletion of the 3′ untranslated region (3′ UTR) of DKC1, encoding the protein dyskerin, was identified by WGS, despite being missed by whole exome sequencing. The deletion segregated with disease across the family and resulted in reduced levels of DKC1 mRNA in the proband. We demonstrate that the DKC1 3′ UTR contains two polyadenylation signals, both of which were removed by this deletion, likely causing mRNA instability. Consistent with the major function of dyskerin in stabilization of the RNA subunit of telomerase, hTR, the level of hTR was also reduced in the proband, providing a molecular basis for his very short telomeres. This study demonstrates that the terminal region of the 3′ UTR of the DKC1 gene is essential for gene function and illustrates the importance of analyzing regulatory regions of the genome for molecular diagnosis of inherited disease.

Updated Australian consensus statement on management of inherited bleeding disorders in pregnancy

INTRODUCTION

There have been significant advances in the understanding of the management of inherited bleeding disorders in pregnancy since the last Australian Haemophilia Centre Directors' Organisation (AHCDO) consensus statement was published in 2009. This updated consensus statement provides practical information for clinicians managing pregnant women who have, or carry a gene for, inherited bleeding disorders, and their potentially affected infants. It represents the consensus opinion of all AHCDO members; where evidence was lacking, recommendations have been based on clinical experience and consensus opinion.

MAIN RECOMMENDATIONS

During pregnancy and delivery, women with inherited bleeding disorders may be exposed to haemostatic challenges. Women with inherited bleeding disorders, and their potentially affected infants, need specialised care during pregnancy, delivery, and postpartum, and should be managed by a multidisciplinary team that includes at a minimum an obstetrician, anaesthetist, paediatrician or neonatologist, and haematologist. Recommendations on management of pregnancy, labour, delivery, obstetric anaesthesia and postpartum care, including reducing and treating postpartum haemorrhage, are included. The management of infants known to have or be at risk of an inherited bleeding disorder is also covered.

CHANGES IN MANAGEMENT AS A RESULT OF THIS STATEMENT

Key changes in this update include the addition of a summary of the expected physiological changes in coagulation factors and phenotypic severity of bleeding disorders in pregnancy; a flow chart for the recommended clinical management during pregnancy and delivery; guidance for the use of regional anaesthetic; and prophylactic treatment recommendations including concomitant tranexamic acid.

Dynamic changes in dna methylation status in peripheral blood Mononuclear cells following an acute bout of exercise: Potential impact of exercise-induced elevations in interleukin-6 concentration

The aim of the present study was to examine the relationship between interleukin (IL)-6 concentrations and DNA methylation in the peripheral blood mononuclear cells (PBMCs) of trained runners after a bout of prolonged, strenuous exercise. Eight healthy trained males completed a treadmill run at 60% vVO(2max) for 120 min followed by a 5-km time trial in a fasted condition. Whole blood samples were taken prior to, immediately before and 24 h following exercise. From these samples, PBMCs were isolated for analysis and plasma IL-6 concentrations were measured. The methylation status of DNA extracted from PBMCs was analysed using the Illumina 27k methylation beadchip platform. Global DNA methylation status was unaltered immediately and up to 24 hours following a bout of prolonged exercise in comparison to pre-exercise. Despite no change in global DNA methylation, plasma IL-6 concentrations were significantly related to the DNA methylation status of 11 genes. Our study demonstrates that the methylome is stable, while discovering a novel link between exercise-induced increases in circulating IL-6 and the DNA methylation status of 11 individual genes. Based on our preliminary findings, the mechanisms by which changes in plasma IL-6 concentrations and DNA methylation in response to exercise interact require further study.

Methylation of IL-2 promoter at birth alters the risk of asthma exacerbations during childhood

BACKGROUND

Epigenetic modifications may have a role in asthma susceptibility.

OBJECTIVE

To investigate whether epigenetic modification at birth of a CpG site necessary for the regulation of IL-2 transcription (IL-2 Site1) is associated with the development of asthma during childhood.

METHODS

Methylation of IL-2 Site1 was assessed in cord blood from 303 children (225 with atopic mothers); as controls, we measured methylation of a site not important in the transcription of IL-2 (IL-2 Site7) and methylation of the LINE-1 repetitive element. Children were followed to the age of 8 years. Information on severe asthma exacerbations and hospital admissions was collected from child's primary care medical record. To account for potential confounding by bronchiolitis, we used exacerbations/hospitalizations after age 1 year as primary outcomes.

RESULTS

There were 49 severe exacerbations amongst 33 children, and 22 hospital admissions amongst 11 children. The risk of asthma exacerbation increased 1.07-fold (95% CI 1.01-1.14, P = 0.03) and the risk of hospital admission increased 1.12-fold (95% CI 1.04-1.20, P = 0.002) for each one per cent increase in IL-2 Site1 methylation. Children who were admitted to hospital at any time-point had significantly higher IL-2 Site1 methylation than children not admitted to hospital (P = 0.007). There was a significant interaction between age at exacerbation (P = 0.03) or hospital admission (P = 0.02) and methylation, with the effect of methylation increasing with increasing age. Methylation of the control IL-2 Site7 or LINE-1 was not a significant predictor of asthma exacerbations/hospital admission, and we found no association between IL-2 Site1 methylation and hospital admissions for other reasons (0.99 [0.92-1.06]). Cord blood mononuclear cell phytohemagglutinin-stimulated lymphoproliferative responses decreased significantly with increasing IL-2 Site1 methylation (P < 0.001).

CONCLUSIONS

Increasing methylation in cord blood of a functional CpG site in the IL-2 promoter is associated with increased likelihood of severe asthma exacerbations and hospital admissions for asthma/wheeze between ages of 2 and 8 years.

Association between physical activity and risk of bleeding in children with hemophilia

CONTEXT

Vigorous physical activity is thought to increase risk of bleeds in children with hemophilia, but the magnitude of the risk is unknown.

OBJECTIVE

To quantify the transient increase in risk of bleeds associated with physical activity in children with hemophilia.

DESIGN, SETTING, AND PARTICIPANTS

A case-crossover study nested within a prospective cohort study was conducted at 3 pediatric hemophilia centers in Australia between July 2008 and October 2010. A total of 104 children and adolescent boys aged 4 through 18 years with moderate or severe hemophilia A or B were monitored for bleeds for up to 1 year. Following each bleed, the child or parent was interviewed to ascertain exposures to physical activity preceding the bleed. Physical activity was categorized according to expected frequency and severity of collisions. The risk of bleeds associated with physical activity was estimated by contrasting exposure to physical activity in the 8 hours before the bleed with exposures in two 8-hour control windows, controlling for levels of clotting factor in the blood.

MAIN OUTCOME MEASURES

Association of physical activity and factor level with risk of bleeding.

RESULTS

The participants were observed for 4839 person-weeks during which time 436 bleeds occurred. Of these, 336 bleeds occurred more than 2 weeks after the preceding bleed and were used in the primary analysis of risk. Compared with inactivity and category 1 activities (eg, swimming), category 2 activities (eg, basketball) were associated with a transient increase in the risk of bleeding (30.6% of bleed windows vs 24.8% of first control windows; odds ratio, 2.7; 95% CI, 1.7-4.8, P < .001). Category 3 activities (eg, wrestling) were associated with a greater transient increase in risk (7.0% of bleed windows vs 3.4% of first control windows; odds ratio, 3.7; 95% CI, 2.3-7.3, P < .001). To illustrate absolute risk increase, for a child who bleeds 5 times annually and is exposed on average to category 2 activities twice weekly and to category 3 activities once weekly, exposure to these activities was associated with only 1 of the 5 annual bleeds. For every 1% increase in clotting factor level, bleeding incidence was lower by 2% (95% CI, 1%-3%; P = .004).

CONCLUSIONS

In children and adolescents with hemophilia, vigorous physical activity was transiently associated with a moderate relative increase in risk of bleeding. Because the increased relative risk is transient, the absolute increase in risk of bleeds associated with physical activity is likely to be small.

Feasibility of short message service to document bleeding episodes in children with haemophilia

The increasing emphasis on home-based treatment for the management of children with haemophilia has meant that many of these children no longer regularly report to a medical facility. Consequently, it is difficult to monitor incidence of bleeding episodes. The aim of this study was to assess the feasibility of using a short message service (SMS) to monitor incidence of bleeding episodes in children with haemophilia. One hundred and four children with moderate and severe haemophilia A or B took part in a 1-year prospective study between 2008 and 2010. Children or their parents were asked to maintain a bleeds diary. They received a weekly SMS asking whether there had been a bleeding episode in the preceding week. Response rates were calculated. Children were followed for a total of 4839 person-weeks. SMS replies were received for 4201 weeks. Thus, the rate of follow-up was 86.8%. Median responses rates were 94.2% (IQR: 86.1-100%). Weekly SMS is a feasible reporting tool for documenting bleeding episodes in children with haemophilia. It is associated with high response rates and minimal expense and intrusion. The use of SMS could be extended to encourage compliance to prophylactic treatment, particularly in adolescents with haemophilia.

Estimation of transient increases in bleeding risk associated with physical activity in children with haemophilia

Background

Although it is widely appreciated that vigorous physical activity can increase the risk of bleeding episodes in children with haemophilia, the magnitude of the increase in risk is not known. Accurate risk estimates could inform decisions made by children with haemophilia and their parents about participation in physical activity and aid the development of optimal prophylactic schedules. The aim of this study is to provide an accurate estimate of the risks of bleeding associated with vigorous physical activity in children with haemophilia.

Methods/Design

The study will be a case-crossover study nested within a prospective cohort study. Children with moderate or severe haemophilia A or B, recruited from two paediatric haematology departments in Australia, will participate in the study. The child, or the child's parent or guardian, will report bleeding episodes experienced over a 12-month period. Following a bleeding episode, the participant will be interviewed by telephone about exposures to physical activity in the case period (8 hours before the bleed) and 2 control periods (an 8 hour period at the same time on the day preceding the bleed and an 8 hour period two days preceding the bleed). Conditional logistic regression will be used to estimate the risk of participating in vigorous physical activity from measures of exposure to physical activity in the case and control periods.

Discussion

This case-control study will provide estimates of the risk of participation in vigorous physical activity in children with haemophilia.

Lack of somatic alterations of MC1R in primary melanoma

Germline variation of the melanocortin 1 receptor gene (MC1R) is a risk factor for cutaneous melanoma. Recent studies have indicated that the risk is significantly higher for melanomas with somatic BRAF mutations, suggesting that MC1R variants may have a more specific role than their demonstrated effects on skin and hair pigmentation. To address the possibility that MC1R may act like a tumor suppressor gene by creating a permissive condition for melanocytes with specific somatic mutations to proliferate or survive, we analyzed 103 primary melanomas for somatic MC1R mutations and copy number alterations. This cohort included melanomas from skin with and without chronic sun-induced damage, mucosal membranes, and acral skin (palms, soles, and subungual). We did not find somatic mutations or frequent DNA copy number alterations at the MC1R locus, nor any skewed pattern of copy number alterations that would favor one allele type over the other. In conclusion, our findings indicate that MC1R is not a frequent target of somatic alterations in melanoma.

Blue blood

In a world of increasing immigration of a diverse range of nationalities, hereditary hemoglobin variants will be increasingly encountered, and should be considered in infants and children presenting with low saturations. We present a case report of an infant presenting with low oxygen saturations, who was extensively investigated before the correct diagnosis became apparent. Initial haemoglobin electrophoresis was normal, but subsequently abnormal on repeat testing. With further screening, a number of affected family members have since been identified.

The effect of an exercise intervention on aerobic fitness, strength and quality of life in children with haemophilia (ACTRN012605000224628)

BACKGROUND

Children with haemophilia have lower levels of fitness and strength than their healthy peers. We present the protocol of a study designed to determine whether an exercise intervention improves quality of life, aerobic fitness and strength in children with haemophilia.

METHODS/DESIGN

The study will be a randomised, assessor-blinded, controlled trial of exercise treatment. Seventy children aged between 6 and 18 years with haemophilia or von Willebrand disease will be recruited from two paediatric haemophilia clinics in NSW. Each participant will be allocated to an exercise group or a control group using a concealed allocation procedure. The control group will receive usual medical care while the intervention group will receive usual medical care plus an exercise program for 12 weeks. Outcomes (VO2peak, knee extensor strength and quality of life) will be measured at baseline and on completion of the exercise program by a blinded assessor. The primary analysis will be conducted on an intention to treat basis. The effects of the exercise intervention on each of the three primary outcomes will be estimated from between-group differences in the mean outcome adjusted for baseline scores.

DISCUSSION

This study will be the first randomised controlled trial to examine the effects of a structured exercise program on fitness and quality of life in children with haemophilia.

Treatment of an infant with X‐linked severe combined immunodeficiency (SCID‐X1) by gene therapy in Australia

OBJECTIVE

To report the outcome of gene therapy in an infant with X-linked severe combined immunodeficiency (SCID-X1), which typically causes a lack of T and natural killer (NK) cells.

DESIGN AND SETTING

Ex-vivo culture and gene transfer procedures were performed at The Children's Hospital at Westmead, Sydney, NSW, in March 2002. Follow-up to March 2005 (36 months) is available.

PATIENT

A 9-month-old male infant with confirmed SCID-X1 (including complete absence of T cells) with an NK+ phenotype (a less common variant of SCID-X1), and no HLA-identical sibling donor available for conventional bone marrow transplantation.

PROCEDURE

CD34+ haemopoietic progenitor cells were isolated from harvested bone marrow and cultured with cytokines to stimulate cellular replication. Cells were then genetically modified by exposure to a retrovirus vector encoding human gamma c (the common gamma chain of several interleukin receptors; mutations affecting the gamma c gene cause SCID-X1). Gene-modified cells (equivalent to 1.3 x 10(6) CD34+/gamma c+ cells/kg) were returned to the infant via a central line.

RESULTS

T cells were observed in peripheral blood 75 days after treatment, and levels increased rapidly to 0.46 x 10(9) CD3+ cells/L at 5 months. Within 2 weeks of the appearance of T cells, there was a distinct clinical improvement, with early weight gain and clearance of rotavirus from the gut. However, T-cell levels did not reach the reference range, and immune reconstitution remained incomplete. The infant failed to thrive and developed weakness, hypertonia and hyperreflexia in the legs, possibly the result of immune dysregulation. He went on to receive a bone marrow transplant from a matched unrelated donor 26 months after gene therapy.

CONCLUSIONS

This is the first occasion that gene therapy has been used to treat a genetic disease in Australia. Only partial immunological reconstitution was achieved, most likely because of the relatively low dose of gene-corrected CD34+ cells re-infused, although viral infection during the early phase of T-cell reconstitution and the infant's NK+ phenotype may also have exerted an effect.

Reliability and reproducibility of classification of children as "bleeders" versus "non-bleeders" using a questionnaire for significant mucocutaneous bleeding

The diagnosis of type 1 von Willebrand disease (VWD), the most common inherited bleeding disorder in humans, is greatly dependent on an accurate diagnosis of significant mucocutaneous bleeding. In a previous study, the authors modified the criteria of the International Society on Thrombosis and Haemostasis for significant mucocutaneous bleeding to a format, the Hospital for Sick Children (HSC) criteria, that was more applicable to diagnose significant mucocutaneous bleeding in children. To assess the reliability and reproducibility of classification of subjects as "bleeders" versus "non-bleeders" using a questionnaire for significant mucocutaneous bleeding targeted to children, 39 subjects interviewed for a previous HSC VWD study were reinterviewed for the current study. The original bleeding classification was confirmed in 80% of subjects interviewed for a second time, indicating that this method of classification is reproducible (kappa = 0.65), with a "substantial" agreement among the investigators who reviewed the questionnaire responses (kappa = 0.71). The validity and utility of the HSC questionnaire for primary screening of children with suspected mucocutaneous bleeding disorders merits assessment in further clinical studies.

Serious infections from Bacillus sp

Serious infections caused by organisms of the genus Bacillus developed in seven patients. Five drug abusers had either endocarditis or osteomyelitis, one leukemic patient had necrotizing fasciitis, and one patient had a ventriculoatrial shunt infection with recurrent bacteremia. All patients recovered. Experience with these cases reemphasizes the importance of not dismissing Bacillus organisms as culture contaminants, especially when isolated from blood, body fluids, or closed-space infections.

Tuberculoma of the brain

Four patients with cerebral tuberculomas had presenting manifestations that included seizure disorder, exophthalmos, or extremity weakness. Although rare in this country, this diagnosis should not be overlooked in such patients, since combined surgical and medical therapy may be curative.

Staphylococcus aureus bacteremia: relationship between formation of antibodies to teichoic acid and development of metastatic abscesses

Of 50 patients with bacteremia due to Staphylococcus aureus but without clinical evidence of endocarditis, 24 developed antibodies to the cell wall teichoic acid of S. aureus that were demonstrable by counterimmunoelectrophoresis. However, only 16 of the 24 patients developed titers of antibodies high enough for detection by passive gel diffusion. Eleven of the 16 patients developed evidence of complications due to metastatic infection. In contrast, of the 34 patients who were antibody-negative by gel diffusion, only one patient developed evidence of metastatic seeding. Thus, the development of antibodies to teichoic acid at a level detectable by the gel diffusion technique is regularly associated with complicated infections due to S. aureus that require more prolonged therapy, whereas bacteremic patients not developing such an antibody response rarely develop complications and may be treated with a two-week course of therapy.

Prophylactic antibiotics and wound infections following laminectomy for lumber disc herniation

The authors review 531 consecutive operations for lumbar disc herniation performed on 496 patients by one neurosurgeon to determine the effect of prophylactic antibiotics upon postoperative wound infections. In this retrospective analysis 16 instances of sepsis were found, 11 considered to be major and five minor. In the 128 cases in which no antibacterial agents were given, 11 major and 1 minor infection occurred. Four minor infections developed in the 402 occasions when antibiotics were given in the perioperative period. Men had a significantly greater risk of developing infection than women. These data suggest that pre- and postoperative antibiotic therapy directed at a narrow spectrum of microorganisms reduced the incidence of significant wound infections in patients undergoing laminectomy for lumbar disc herniation.