ABSTRACT Background Children with transfusion‐dependent thalassemia (TDT), also known as thalassemia major, require monthly blood transfusions and regular iron chelation therapy for long‐term survival. While the burden of caring for these children is recognized, little has been done to address the parents’ experience. Procedure A 38‐item parent self‐report was included in the previously designed disease‐specific tool, the transfusion‐dependent quality‐of‐life questionnaire (TranQol), to identify the issues they may be facing. We wanted to ensure that the self‐report was reliable and valid. Questionnaires were given to parents during their children's routine clinic visits as part of a multi‐center North American study of the TranQol. Construct validity was assessed using Pearson's correlation with the Pediatric Quality of Life (PedsQL) Family Impact Module (FIM) (hypothesis: correlation of 0.4–0.6). Results Sixty‐seven parents completed both the TranQol and PedsQL Family Impact Module questionnaires at baseline. There was substantial correlation ( r = 0.76) between TranQol parent self‐report scores (median 63, interquartile range [IQR]: 53–76) and PedsQL Family Impact Module scores (median 77, IQR: 59–89). Conclusions The median PedsQL FIM score was similar to previously reported scores for parents of children with sickle cell disease. The TranQol parental burden tool demonstrated construct validity was internally reliable (Cronbach's α = 0.94) and had acceptable test–retest reliability (intraclass correlation coefficient [ICC] = 0.81), for future research into TDT. In addition, this tool could also be used to help clinicians assess the impact of the disease on parents to potentially target appropriate support and care that is required.

Background: Children with sickle cell disease (SCD) in Canada are routinely supplemented with folic acid to provide sufficient folate for the increased demands of erythropoiesis. However, with the mandatory folic acid fortification of refined grains and pharmacotherapies that extend the lifespan of sickled red blood cells (RBC), this clinical practice is in question. Objectives: This study aims to determine the efficacy of folic acid supplementation by measuring the effect of 12 f 1 wk of 1 mg/d folic acid, compared with placebo, on concentrations of RBC folate (primary outcome), serum folate, and 1-carbon-related metabolites, and clinical outcomes in children with SCD. Methods: In this double-blind randomized controlled noninferiority cross-over trial, 31 children with SCD, aged 2-19 y, were enrolled and randomly assigned (1:1 with blocks of 4) to 1 mg/d folic acid, the current standard of care, or a placebo for 12 f 1 wk. After a 12 f 1 wk washout period, treatments were reversed. Results: The mean [95% confidence interval (CI)] difference in endline RBC folate concentrations across treatments was-179 (-260, -99) nmol/L, with the lower boundary of the CI exceeding noninferiority but the upper boundary not (P = 0.0001; modified intention-to-treat). There was no significant difference in the number of participants who had RBC folate deficiency after each treatment (P = 0.059). No participants presented with serum folate deficiency (<7 nmol/L). There were no significant differences observed in 1-carbon metabolite concentrations (total homocysteine, S-adenosylhomo-cysteine, S-adenosylmethionine, vitamin B12, or methylmalonic acid), hematological measures, nor clinical outcomes (specifically acute pain episodes or megaloblastic changes) when individuals were supplemented with folic acid in comparison with placebo. Conclusions: Despite mandatory food fortification and advances in the medical treatment of SCD, it appears that some children with this condition may still benefit from daily folic acid supplementation. Whether this translates to improved clinical outcomes remains uncertain. This trial was registered at clinicaltrials.gov as NCT04011345 (https://clinicaltrials.gov/study/NCT04011345).

BACKGROUND:The NuProtect study reported data on the immunogenicity, efficacy and tolerability of simoctocog alfa (Nuwiq® ) in 108 previously untreated patients with severe haemophilia A planned to be treated for ≥100 exposure days or up to 5 years. The NuProtect-Extension study collected long-term prophylaxis data in children with severe haemophilia A.METHODS:Patients who completed the NuProtect study according to the protocol were eligible for the NuProtect-Extension study, a prospective, multinational, non-controlled, Phase 3b study.RESULTS:Of 48 patients who entered the extension study, 47 (median age 2.8 years) received prophylaxis with simoctocog alfa for a median of 24 months, with 82%-88% on a twice-weekly or less regimen. No patient developed FVIII inhibitors during the extension study. The median (IQR) annualized bleeding rate (ABR) during prophylaxis was 0 (0-0.5) for spontaneous bleeding episodes (BEs) and 1.00 (0-1.95) for all BEs. ABRs estimated using a negative binomial model were .28 (95% CI: .15, .53) for spontaneous and 1.62 (95% CI: 1.09, 2.42) for all BEs. During the median follow-up of 24 months, 34 (72%) patients had zero spontaneous BEs and 46 (98%) had zero spontaneous joint BEs. Efficacy in treating BEs was excellent or good for 78.2% of rated BEs, and efficacy of surgical prophylaxis was excellent for two rated surgeries. No treatment-related adverse events were reported.CONCLUSION:No FVIII inhibitors developed during long-term prophylaxis in the NuProtect-Extension study. Prophylaxis with simoctocog alfa was efficacious and well-tolerated, and is therefore an attractive long-term option for children with severe haemophilia A.

Introduction Simoctocog alfa (Nuwiq (R)) is a 4th generation recombinant FVIII with proven efficacy for the prevention and treatment of bleeding episodes (BEs) in previously treated patients with severe haemophilia A. The NuProtect study assessed the immunogenicity, efficacy and safety of simoctocog alfa in 108 previously untreated patients (PUPs). The incidence of high-titre inhibitors was 16.2% and no patients with non-null F8 mutations developed inhibitors.Aim To report the efficacy and safety results from the NuProtect study.Methods PUPs received simoctocog alfa for prophylaxis, treatment of BEs, or as surgical prophylaxis. The efficacy of prophylaxis (during inhibitor-free periods) was assessed using annualised bleeding rates (ABRs). The efficacy in treating BEs and in surgical prophylaxis was assessed using a 4-point scale. Adverse events were recorded throughout the study.Results Of 108 PUPs treated with simoctocog alfa, 103 received at least one prophylactic dose and 50 received continuous prophylaxis for at least 24 weeks. In patients on continuous prophylaxis, the median ABR was 0 (mean 0.5) for spontaneous BEs and 2.5 (mean 3.6) for all BEs. In 85 patients who had BEs, efficacy of BE treatment was excellent or good for 92.9% (747/804) of rated BEs; 92.3% of BEs were treated with 1 or 2 infusions. The efficacy of surgical prophylaxis was excellent or good for 94.7% (18/19) of rated procedures. There were no safety concerns and no thromboembolic events.Conclusion Simoctocog alfa was efficacious and well tolerated as prophylaxis, surgical prophylaxis and for the treatment of BEs in PUPs with severe haemophilia A.

Background This study examined the structural outcomes for joints of boys with severe hemophilia A receiving frequency/dose-escalated primary prophylaxis using magnetic resonance imaging (MRI), and the importance of interval MRI changes. Methods Forty-six subjects (27 with interval studies) were evaluated by radiographs (X-rays) and mid- and end-of-study MRIs (using the International Prophylaxis Study Group scale), as part of the Canadian Hemophilia Prophylaxis Study. The primary outcome was the presence of MRI osteochondral findings. Results The median (range) time on study at the end-of-study MRI examination was 9.6 (4.8-16.0) years, during which 18 of 46 subjects (39%) had osteochondral changes in at least one joint. An interval change in MRI score of at least 1 point was observed in 44% of joints (43 ankles, 21 elbows, 4 knees); at least one joint showed this change in all 27 subjects. Self-reported interval hemarthrosis was associated with a higher likelihood of interval osteochondral change (odds ratio [OR], 1.49; 95% confidence interval [CI] = 1.08-2.06). Presence of synovial hypertrophy or hemosiderin on interval MRIs was associated with an OR of 4.71 (95% CI, 1.92-11.57) and 5.25 (95% CI, 2.05-13.40) of later osteochondral changes on MRI. Discussion MRI changes were seen in 39% of subjects. Interval index joint bleeding was associated with an increased risk of later MRI changes, and earlier soft-tissue changes were associated with subsequent osteochondral changes. [GRAPHICS]

INTRODUCTION:FVIII inhibitor development is the most serious contemporary treatment complication in haemophilia A, particularly in previously untreated patients (PUPs). No inhibitors developed in clinical trials in previously treated patients treated with simoctocog alfa (Nuwiq), a fourth-generation recombinant FVIII produced in a human cell line. METHODS:The NuProtect study investigated the immunogenicity of simoctocog alfa in PUPs. NuProtect was a prospective, multinational, open-label, non-controlled, phase III study. PUPs with severe haemophilia A (FVIII:C <1%) of any age and ethnicity were treated with simoctocog alfa for 100 exposure days or a maximum of 5 years. Patients were true PUPs without prior exposure to FVIII concentrates or blood components. Inhibitor titres were measured with the Nijmegen-modified Bethesda assay; cut-off for positivity was 0.6 BU mL-1 (≥0.6 to <5 low-titre, ≥5 high titre). RESULTS:A total of 108 PUPs with a median age at first treatment of 12.0 months (interquartile range: 8.0-23.5) were treated with simoctocog alfa. F8 mutation type was known for 102 patients (94.4%) of whom 90 (88.2%) had null F8 mutations and 12 (11.8%) had non-null mutations. Of 105 PUPs evaluable for inhibitor development, 28 (26.7%) developed inhibitors; 17 high titre (16.2%) and 11 low titre (10.5%). No PUPs with non-null F8 mutations developed inhibitors. CONCLUSION:In the NuProtect study, the rate of inhibitor development in PUPs with severe haemophilia A treated with simoctocog alfa was lower than the rate reported for hamster-cell-derived recombinant factor VIII products in other recent clinical trials. No inhibitors were reported in PUPs with non-null F8 mutations.

Introduction Recombinant factors VIII and IX Fc (rFVIIIFc/rFIXFc) became available in Canada in 2016 and were the only extended half-life (EHL) factor concentrates available in Canada until 2018. Objectives We aim to describe the change in product utilization in Canadians who switched to rFVIIIFc/rFIXFc. Methods This prospective and retrospective cohort study enrolled males aged >= 6 years with moderate or severe haemophilia who switched to rFVIIIFc/rFIXFc and those who remained on standard half-life (SHL) between 2016 and 2018. Factor utilization and annualized bleeding rates (ABR) were collected at baseline, 1-year and 2-years. Due to low prospective enrolment (n = 25 switchers), prospective and retrospective data were pooled. Results 125 switchers (93 rFVIIIFc, 32 rFIXFc) and 33 non-switchers were included. The median age was 17 (rFVIIIFc) and 38 years (rFIXFc). Prior to switch, over 80% were on prophylaxis. There was a statistically significant reduction in the prescribed weekly prophylactic dose after the switch to rFVIIIFc/rFIXFc for all age groups, with a corresponding reduction (15-16%) in actual annualized FIX utilization in switchers (combined adults and children) to rFIXFc, and a smaller non-significant reduction in actual annualized FVIIII utilization (7%) in children who switched to rFVIIIFc. A significant reduction in the median ABR was only observed in children who switched to rFVIIIFc, but not in adults who switched to rFVIIIFc or rFIXFc. Conclusion Switching from SHL to EHL products led to a small reduction in factor utilization, while preserving a low ABR in children and adults with haemophilia. Further patient-reported outcomes data will further elucidate the role of EHL in the haemophilia landscape.

Abstract Background Previous research has shown that bone mineral density (BMD), a measure of bone strength, may be lower among people with haemophilia. However, the majority of this research has been done in adults and in countries where the treatment for haemophilia differs from the standard of care in Canada, and there is a lack of paediatric data. Aims The primary objective of this study was to determine whether Canadian children and youth with severe haemophilia A and B have BMD similar to healthy controls matched for height, age and weight (HAW-score). Secondary objectives included the exploration of any association between BMD and the following variables: factor replacement regimen, Hemophilia Joint Health Score (HJHS), bleeding history, physical activity level, and dietary intake of calcium, vitamin D, vitamin K and protein. Methods A cross-sectional observational study was designed to determine the BMD of children with severe haemophilia A and B in Canada. Ethical approvals were obtained from participating institutions. Thirty-eight participants aged 3–18 with severe haemophilia A and B were recruited from two treatment centres in Canada. Subjects underwent dual-energy X-ray absorptiometry (DXA) scan, and data was collected from regular clinic visit to identify factor replacement regimen, HJHS, and number of joint bleeds over the lifespan. Physical activity level and dietary intake of calcium, vitamin D, vitamin K and protein were identified using self-report questionnaires. Results Participants showed a mean spine BMD Z-score and HAW-score higher than controls, with no participants showing a spine Z-score or HAW-score of <0. Hip BMD score was within normal range, and 2 participants had a Z-score and HAW-score of <−2. Total body BMD score was lower than controls, with 6 participants having a Z-score of <−2.0, and 3 participants having a HAW-score of <−2.0. Factor replacement regimen, HJHS, calcium intake, and physical activity level had no relationship to BMD Z-score or HAW-score. Low intake of vitamin D was associated with a low hip and spine BMD Z-score and HAW-score. Participants with a HJHS joint score greater than 0 had a higher total body HAW-score than those who had a joint score of 0. Conclusion Canadian children with severe haemophilia A and B demonstrate differences in spine and total body BMD from height-, age-, and weight-matched controls, where spine BMD is higher than controls and total body BMD is lower than controls. Studies with a larger sample size are needed to clarify the status of BMD in children with haemophilia treated with primary prophylaxis.

Background Peripheral vascular access and venipuncture are major causes of distress and anxiety for children and their parents. This is especially difficult for patients with hemoglobinopathies (thalassemia major and sickle cell disease) who require chronic blood transfusions. These patients require peripheral venous access for regular blood transfusions and (in the case of sickle cell disease) for automated red cell exchange procedures. Peripheral intravenous (PIV) catheters are much preferred to central venous lines as they carry far fewer risks. However, when patients experience multiple unsuccessful attempts to initiate a PIV, it can be traumatizing and cause anxiety for future visits. Establishing therapeutic trust and ensuring a smooth experience are of paramount importance for these chronic patients who require regular blood transfusions. Aim The purpose of this study was to determine whether ultrasound-guided PIV insertion decreases PIV-associated pain and anxiety, and whether the number of attempts and amount of time spent accessing PIVs in children with difficult peripheral intravenous (DPIV) access is reduced. Materials and Methods This was a pilot study with both retrospective and prospective components. Hemoglobinopathies are relatively rare in our population and our study cohort was small (N = 18). Results We identified four DPIV access patients. We recorded each time these patients had a PIV inserted as an encounter. Discussion/Conclusion We found that while there was a small amount of time gained by using ultrasound-guided PIV insertion, patient and parent satisfaction was significantly improved.

Background KRAS (KRAS proto-oncogene, GTPase; OMIM: 190,070) encodes one of three small guanosine triphosphatase proteins belonging to the RAS family. This group of proteins is responsible for cell proliferation, differentiation and inhibition of apoptosis. Gain-of-function variants in KRAS are commonly found in human cancers. Non-malignant somatic KRAS variants underlie a subset of RAS-associated autoimmune leukoproliferative disorders (RALD). RALD is characterized by splenomegaly, persistent monocytosis, hypergammaglobulinemia and cytopenia, but can also include autoimmune features and lymphadenopathy. In this report, we describe a non-malignant somatic variant in KRAS with prominent clinical features of massive splenomegaly, thrombocytopenia and lymphopenia. Case presentation A now-11-year-old girl presented in early childhood with easy bruising and bleeding, but had an otherwise unremarkable medical history. After consulting for the first time at 5 years of age, she was discovered to have massive splenomegaly. Clinical follow-up revealed thrombocytopenia, lymphopenia and increased polyclonal immunoglobulins and C-reactive protein. The patient had an unremarkable bone marrow biopsy, flow cytometry showed no indication of expanded double negative T-cells, while malignancy and storage disorders were also excluded. When the patient was 8 years old, whole exome sequencing performed on DNA derived from whole blood revealed a heterozygous gain-of-function variant in KRAS (NM_004985.5:c.37G > T; (p.G13C)). The variant was absent from DNA derived from a buccal swab and was thus determined to be somatic. Conclusions This case of idiopathic splenomegaly in childhood due to a somatic variant in KRAS expands our understanding of the clinical spectrum of RAS-associated autoimmune leukoproliferative disorder and emphasizes the value of securing a molecular diagnosis in children with unusual early-onset presentations with a suspected monogenic origin.

Objective The primary objective of this study was to assess whether there are different patterns (classes) of joint health in young boys with severe haemophilia A (SHA) prescribed primary tailored prophylaxis. We also assessed whether age at first index joint bleed, blood group, FVIII gene abnormality variant, factor VIII trough level, first-year bleeding rate and adherence to the prescribed prophylaxis regimen significantly predicted joint damage trajectory, and thus class membership. Methods Using data collected prospectively as part of the Canadian Hemophilia Primary Prophylaxis Study (CHPS), we implemented a latent class growth mixture model technique to determine how many joint damage classes existed within the cohort. We used a multinomial logistic regression to predict the odds of class membership based on the above predictors. We fitted a survival model to assess whether there were differences in the rate of dose escalation across the groups. Results We identified three distinct classes of trajectory: persistently low, moderately increasing and rapidly increasing joint scores. By multinomial regression, we found that only age at first index joint bleed predicted rapidly increasing joint scores. The rapidly increasing joint score class group moved through dose escalation significantly faster than the other two groups. Conclusions Using tailored prophylaxis, boys with SHA follow one of three joint health trajectories. By using knowledge of disease trajectories, clinicians may be able to adjust treatment according to a subject's predicted long-term joint health and institute cost-effective programmes of prophylaxis targeted at the individual subject level.

Background: Recombinant factors VIII and IX Fc (rFVIIIFc/rFIXFc) were the only available extended half-life (EHL) products in Canada during 2016 to 2018. Objectives: To evaluate if patient-reported outcome measures (PROMs) improved in Canadian persons with hemophilia who switched from standard half-life (SHL) to EHL products (rFVIIIFc/rFIXFc). Patients/Methods: This prospective cohort study enrolled persons with moderate or severe hemophilia aged >= 6 years who switched to rFVIIIFc/rFIXFc (2016-2018) and those who remained on SHL. Health-related quality of life (HRQoL) was assessed using the Haemophilia-specific Quality of Life (Haem-A-QoL) and 36-item Short-Form Survey (SF-36) at baseline, 3-months, 12 months, and 24 months. Other PROMs included the Work Productivity and Impairment Questionnaire, chronic pain scale, partner/parent ratings of mood, International Physical Activity Questionnaire, and Treatment Satisfaction Questionnaire for Medication. We identified meaningful changes using minimally important difference for SF-36 and responder definition for Haem-A-QoL. Results: We enrolled 25 switchers (16 rFVIIIFc, 9 rFIXFc) and 33 nonswitchers. Those switched to rFVIIIFc/rFIXFc had improved overall HRQoL, and improved subscale physical activity, mental health, and social functioning at 3 months. The rFIXFc switchers had improved chronic pain and ability to engage in normal activities while the rFVIIIFc switchers had improved treatment satisfaction. There was no change in work impairment after the switch. Observed improvement disappeared by 24 months in most domains. Conclusion: Switching from SHL to rFVIIIFc/rFIXFc resulted in short-term meaningful improvement in overall HRQoL and other PROMs in a small proportion. Longitudinal changes on PROMs are affected by ceiling effects and response shift, warranting further studies in instrument optimization in the era of EHL and nonfactor products.

Sickle cell disease (SCD) is an inherited hemoglobinopathy caused by a variant (rs344) in the HBB gene encoding the β-globin subunit of hemoglobin. Chronic hemolytic anemia and increased erythropoiesis and RBC turnover in individuals with SCD can result in increased needs for folate and other B-vitamins. We assessed B-vitamin status, and the distribution of folate forms, including unmetabolized folic acid (UMFA), in Canadian children with SCD supplemented with 1 mg/d folic acid (current routine practice). Non-fasted serum and plasma samples were analyzed for concentrations of folate, and vitamins B-2, B-6, and B-12. Eleven individuals (45% male; SCD type: HbSS n = 8, HbSC n = 2, HbSβ 0 -Thal n = 1), with a median (IQR) age of 14 (7, 18) years, were included. Total folate concentrations were 3–27 times above the deficiency cut-off (10 nmol/L), and 64% of children had elevated folate levels (>45.3 nmol/L). UMFA (>0.23 nmol/L) was detected in all children, and 36% of participants had elevated levels of UMFA (>5.4 nmol/L). All children were vitamin B-12 sufficient (>150 pmol/L), and the majority (55%) had sufficient B-6 status (>30 nmol/L). Among this sample of Canadian children with SCD, there was limited evidence of B-vitamin deficiencies, but UMFA was detectable in all children.

The heterogeneous manifestations of MYH9-related disorder (MYH9-RD), characterized by macrothrombocytopenia, Dohle-like inclusion bodies in leukocytes, bleeding of variable severity with, in some cases, ear, eye, kidney, and liver involvement, make the diagnosis for these patients still challenging in clinical practice. We collected phenotypic data and analyzed the genetic variants in more than 3,000 patients with a bleeding or platelet disorder. Patients were enrolled in the BRIDGE-BPD and ThromboGenomics Projects and their samples processed by high throughput sequencing (HTS). We identified 50 patients with a rare variant in MYH9. All patients had macrothrombocytes and all except two had thrombocytopenia. Some degree of bleeding diathesis was reported in 41 of the 50 patients. Eleven patients presented hearing impairment, three renal failure and two elevated liver enzymes. Among the 28 rare variants identified in MYH9, 12 were novel. HTS was instrumental in diagnosing 23 patients (46%). Our results confirm the clinical heterogeneity of MYH9-RD and show that, in the presence of an unclassified platelet disorder with macrothrombocytes, MYH9-RD should always be considered. A HTS-based strategy is a reliable method to reach a conclusive diagnosis of MYH9-RD in clinical practice.

The inclusion of familial myeloid malignancies as a separate disease entity in the revised WHO classification has renewed efforts to improve the recognition and management of this group of at risk individuals. Here we report a cohort of 86 acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) families with 49 harboring germline variants in 16 previously defined loci (57%). Whole exome sequencing in a further 37 uncharacterized families (43%) allowed us to rationalize 65 new candidate loci, including genes mutated in rare hematological syndromes ( ADA , GP6, IL17RA, PRF1 and SEC23B ), reported in prior MDS/AML or inherited bone marrow failure series ( DNAH9 , NAPRT1 and SH2B3 ) or variants at novel loci ( DHX34 ) that appear specific to inherited forms of myeloid malignancies. Altogether, our series of MDS/AML families offer novel insights into the etiology of myeloid malignancies and provide a framework to prioritize variants for inclusion into routine diagnostics and patient management.

Background Sickle cell disease (SCD) is a genetic disorder which causes dysfunctional red blood cells (RBC) and is thought to increase requirements for folate, an essential B vitamin, due to increased RBC production and turnover in the disease. High-dose supplementation with 1–5 mg/d folic acid, synthetic folate, has been the standard recommendation for children with SCD. There is concern about whether children with SCD need such high doses of folic acid, following mandatory folic acid fortification of enriched grains in Canada, and advancements in medical therapies which extend the average lifespan of RBCs. In animal and human studies, high folic acid intakes (1 mg/d) have been associated with accelerated growth of some cancers, and the biological effects of circulating unmetabolized folic acid (UMFA), which can occur with doses of folic acid ≥ 0.2 mg/d, are not fully understood. The objective of this study is to determine efficacy of, and alterations in folate metabolism from high-dose folic acid in children with SCD during periods of folic acid supplementation versus no supplementation. Methods In this double-blind randomized controlled cross-over trial, children with SCD ( n = 36, aged 2–19 years) will be randomized to either receive 1 mg/d folic acid, the current standard of care, or a placebo for 12 weeks. After a 12-week washout period, treatments will be reversed. Total folate concentrations (serum and RBC), different folate forms (including UMFA), folate-related metabolites, and clinical outcomes will be measured at baseline and after treatment periods. The sum of the values measured in the two periods will be calculated for each subject and compared across the two sequence groups by means of a test for independent samples for the primary (RBC folate concentrations) and secondary (UMFA) outcomes. Dietary intake will be measured at the beginning of each study period. Discussion As the first rigorously designed clinical trial in children with SCD, this trial will inform and assess current clinical practice, with the ultimate goal of improving nutritional status of children with SCD. Trial registration ClinicalTrials.gov NCT04011345 . Registered on July 8, 2019

Guidelines recommend bone marrow biopsy for tryptase >20ug/L, but systemic mastocytosis (SM) is exceedingly rare in children. Hereditary alpha-tryptasemia (HAT) is caused by a duplication or triplication of the alpha-tryptase gene (TPSAB1), leading to overproduction of alpha-tryptase. HAT affects 6% of the population, with autosomal dominant inheritance. We report the youngest child with tryptase level >20ug/L, who is also the youngest child reported with HAT. Bone marrow biopsy was performed and assessed for mast cell infiltrates and KIT mutation, in addition to staining for tryptase and CD117. Serum and urine PGD2 levels were sent to rule out mast cell activation. Genetic testing was performed from a buccal swab using DNA amplification via digital droplet polymerase chain reaction for TPSAB1. A 3-month-old girl with mosaic Turner syndrome presented to her pediatrician with recurrent episodes of flushing, and gastroesophageal reflux requiring omeprazole. She was otherwise well with no features of SM. Tryptase level at 8 months was 19.8ug/L (normal <11.1ug/L), and 25.3ug/L when repeated. Complete blood count, liver, and renal function tests were normal. Bone marrow biopsy did not reveal evidence of mast cell infiltrate or KIT mutation. Immunohistochemical staining for tryptase and CD117 was negative. Serum and urine PGD2 levels were normal. Amplification of TPSAB1 revealed duplication, consistent with HAT. We propose that in the absence of convincing history of SM, children with elevated tryptase should first have HAT genetic testing prior to bone marrow biopsy, due to the rarity of childhood SM and genetic testing being less invasive.

Canadian children with sickle cell disease (SCD) are routinely supplemented with high-dose folic acid (1 mg/d), synthetic folate, due to increased erythrocyte production and turn-over in the disease. Folate also plays a vital role in one-carbon metabolism. Impairments in this folate-dependent mechanism can also occur due to secondary B-vitamin (vitamin B2, B6 and B12) deficiencies. The study objective was to determine B-vitamin status in Canadian children with SCD. Serum and plasma samples from children diagnosed with SCD were obtained from BC Children's Hospital BioBank (Vancouver, Canada). Samples were analyzed for folate, vitamin B6, and related metabolites using electrospray ionization-liquid chromatography-tandem mass spectrometry. Vitamin B12 concentrations were analyzed using chemiluminescent immunoassay. World Health Organization cut-offs were used to determine deficiencies of folate (<10 nmol/L) and vitamin B12 (<150 pmol/L), and European Food Safety Authority Panel cut-offs were used for vitamin B6 (<30 nmol/L pyridoxal 5'-phosphate; PLP). Medians with interquartile ranges (IQR) are presented. Six individuals (50% male; SCD type: Hgb SS n = 3, Hgb SC n = 2, HbSβ,0-Thal n = 1) were included. Median age of participants was 15 (9, 18) years. Half (50%) of participants were prescribed hydroxyurea (median dose: 21(14, 30) mg/kg/d), and all participants were prescribed 1 mg/d folic acid (adherence data not available). Median serum folate was 55.4 (43.1, 71.9) nmol/L, with levels 3 to 15 times above the cut-off for deficiency. Unmetabolized folic acid (UMFA), unused folic acid in circulation, was detected in all six participants. All participants were vitamin B12 sufficient, with median plasma vitamin B12 of 325 (288, 411) nmol/L. The majority (n = 5; 83%) had sufficient B6 status, with median serum PLP of 39 (36.9, 44.2) nmol/L. In this pilot project, there was limited evidence of B-vitamin deficiencies among Canadian children with SCD. Serum folate levels exceeded the cut-off for deficiency by 3 to 15 times, with all participants having detectable levels of UMFA. A randomized clinical trial re-assessing the routine practice of high-dose folic acid supplementation in children with SCD is warranted. Thrasher Research Fund and Rare Disease Foundation.