Mark J. Belletrutti

Improving diagnostic precision, care and syndrome definitions using comprehensive next-generation sequencing for the inherited bone marrow failure syndromes

Background Phenotypic overlap among the inherited bone marrow failure syndromes (IBMFSs) frequently limits the ability to establish a diagnosis based solely on clinical features. >70 IBMFS genes have been identified, which often renders genetic testing prolonged and costly. Since correct diagnosis, treatment and cancer surveillance often depend on identifying the mutated gene, strategies that enable timely genotyping are essential. Methods To overcome these challenges, we developed a next-generation sequencing assay to analyse a panel of 72 known IBMFS genes. Cases fulfilling the clinical diagnostic criteria of an IBMFS but without identified causal genotypes were included. Results The assay was validated by detecting 52 variants previously found by Sanger sequencing. A total of 158 patients with unknown mutations were studied. Of 75 patients with known IBMFS categories (eg, Fanconi anaemia), 59% had causal mutations. Among 83 patients with unclassified IBMFSs, we found causal mutations and established the diagnosis in 18% of the patients. The assay detected mutant genes that had not previously been reported to be associated with the patient phenotypes. In other cases, the assay led to amendments of diagnoses. In 20% of genotype cases, the results indicated a cancer surveillance programme. Conclusions The novel assay is efficient, accurate and has a major impact on patient care.

Chronic immune thrombocytopenic purpura in children: a survey of the canadian experience.

Background Immune thrombocytopenic purpura (ITP) in children is a common pediatric bleeding disorder with heterogeneous manifestations and a natural history that is not fully understood. To better understand the natural history of chronic ITP and detect response trends and outcomes of therapy, we conducted a 10-year retrospective survey of children from age 1 to 18 years with a diagnosis of chronic ITP. Results Data on 198 patients from 8 Canadian Pediatric Hematology/Oncology centers were analyzed. The majority of patients were female (58%), and were previously diagnosed with acute (primary) ITP (85%). The age at diagnosis of chronic ITP ranged from 1.1 to 17.2 years with a mean of 8.2±4.4 years. Ninety percent of patients received some form of treatment. Untreated patients had a higher mean platelet count at diagnosis of chronic ITP (P=0.009) despite similarities in mean age at first presentation and mean duration of follow-up. Thirty-four (17%) patients underwent splenectomy. Splenectomized patients tended to be significantly older, had a lower mean platelet count at diagnosis of chronic ITP, and had a longer duration of follow-up. Conclusions The results from this study are consistent with published reports.

The impact of category, cytopathology and cytogenetics on development and progression of clonal and malignant myeloid transformation in inherited bone marrow failure syndromes

Inherited bone marrow failure syndromes are a group of rare, heterogeneous genetic disorders with a risk of clonal and malignant myeloid transformation including clonal marrow cytogenetic abnormalities, myelodysplastic syndrome and acute myeloid leukemia. The clinical characteristics, risk classification, prognostic factors and outcome of clonal and malignant myeloid transformation associated with inherited bone marrow failure syndromes are largely unknown. The aims of this study were to determine the impact of category, cytopathology and cytogenetics, the three components of the “Category Cytology Cytogenetics” classification of pediatric myelodysplastic syndrome, on the outcome of clonal and malignant myeloid transformation associated with inherited bone marrow failure. We used data from the Canadian Inherited Marrow Failure Registry. Among 327 patients with inherited bone marrow failure syndrome enrolled in the registry, the estimated risk of clonal and malignant myeloid transformation by the age of 18 years was 37%. The risk of clonal and malignant myeloid transformation varied according to the type of inherited bone marrow failure syndrome but was highest in Fanconi anemia. The development of clonal and malignant myeloid transformation significantly affected overall survival. Mortality varied based on cytopathological group. The largest group of patients had refractory cytopenia. Clonal marrow cytogenetic abnormalities were identified in 87% of patients with clonal and malignant myeloid transformation, and different cytogenetic groups had different impacts on disease progression. We conclude that category, cytopathology and cytogenetics in cases of clonal and malignant myeloid transformation associated with inherited bone marrow failure syndromes have an important impact on outcome and that the classification of such cases should incorporate these factors.

Management and Outcome of Patients With Langerhans Cell Histiocytosis and Single‐Bone CNS‐Risk Lesions: A Multi‐Institutional Retrospective Study

Children with Langerhans cell histiocytosis (LCH) and single‐bone CNS‐risk lesions have been reported to be at increased risk of diabetes insipidus (DI), central nervous system neurodegeneration (CNS‐ND), and recurrence of disease. However, it is unknown whether the addition of chemotherapy or radiotherapy changes outcomes in these patients.

Typhlitis in children with malignancy: a single center experience.

In a case-control study, medical records of all children (below 18 y of age) who were diagnosed with any malignancy between January 1988 and December 2008 were reviewed. Children who developed typhlitis during the course of their malignancy were identified. Age and sex-matched controls who were diagnosed with malignancy during the same time period but did not develop typhlitis were identified (1:4 ratio). The variables that were examined included underlying malignancy, chemotherapy, and final outcome. A total of 410 children (226 males, mean age of 87.29±56.8 mo) with malignancy were recruited. Nine children (0.22%) (4 boys, mean age of 87.56±60.48 mo) developed typhlitis during the course of their disease. In the control group, 36 age and sex-matched children were included (mean age of 87.67±57.91 mo). Children who had Clostridium difficile infection within 8 weeks before developing typhlitis were more likely to develop typhlitis compared with controls (odds ratio 7.99, 95% confidence interval 1.46-43.7, P=0.01). One patient died from typhlitis. Clostridium difficile infection is a risk factor for developing typhlitis in children with cancer. Larger multicenter trials are needed to confirm our conclusions.

Immunogenicity, efficacy and safety of Nuwiq® (human-cl rhFVIII) in previously untreated patients with severe haemophilia A—Interim results from the NuProtect Study

Nuwiq® (Human‐cl rhFVIII) is a fourth generation recombinant FVIII, produced in a human cell line, without chemical modification or protein fusion. No inhibitors developed in studies with Nuwiq® in 201 previously treated patients with haemophilia A (HA). The immunogenicity, efficacy and safety of Nuwiq® in previously untreated patients (PUPs) with severe HA are being assessed in the ongoing NuProtect study.

Recombinant factor VIII Fc fusion protein for immune tolerance induction in patients with severe haemophilia A with inhibitors—A retrospective analysis

Immune tolerance induction (ITI) is the gold standard for eradication of factor VIII inhibitors in severe haemophilia A; however, it usually requires treatment for extended periods with associated high burden on patients and healthcare resources.

Examining the Experiences of Fathers of Children with a Life-Limiting Illness

ABSTRACT Families who have a child diagnosed with a life-limiting illness (LLI) face substantial challenges resulting from the complexity and devastating impact of the condition and potential closeness of death. The experiences of fathers of a child with LLI have been understudied; therefore, this study explored the stresses, experiences, and strategies of these fathers, including their perceptions about support needs. Based on grounded theory, in-depth semi-structured interviews were conducted with 18 fathers of children with LLI. Six fathers had experienced the death of their child. The overarching themes were stresses, means of coping, and perceived needs for support. Generally, fathers in this study struggled relative to discursive and internalized notions of fathers as providers and protectors for their children, combined with an inability to ease their child’s vulnerability to LLI. Participants were engaged in the care of their child with LLI, but several felt marginalized by health care providers in care planning and staff/family communication. Some fathers recognized and valued their support network while others had few supports. Some described personal growth and desired to help other fathers. Practice implications and recommendations include renewed application of family-centered care, overcoming presumptions about fathers’ roles, and recognizing the impact of LLI beyond physical health.

Use of gemcitabine with multi-stage surgical resection as successful second-line treatment of metastatic pancreatoblastoma.

Pancreatoblastoma is a rare pediatric pancreatic malignancy. It confers a worse prognosis if there is metastatic or unresectable disease. We report a case of a 12-year-old boy who presented with pancreatoblastoma of the head of the pancreas with multiple intrahepatic metastases. We successfully treated him using aggressive chemotherapy, multi-stage surgery, and gemcitabine chemotherapy, which has not been described as treatment for pancreatoblastoma. Rare childhood malignancies such as pancreatoblastoma require a coordinated, multidisciplinary approach and frequent reassessment of therapeutic interventions. Complete surgical resection is important for cure and may require complex, aggressive, multiple-stage surgical procedures with concurrent or novel chemotherapy.

The Clinical Impact of Copy Number Variants in Inherited Bone Marrow Failure Syndromes

Inherited bone marrow failure syndromes comprise a genetically heterogeneous group of diseases with hematopoietic failure and a wide array of physical malformations. Copy number variants were reported in some inherited bone marrow failure syndromes. It is unclear what impact copy number variants play in patients evaluated for a suspected diagnosis of inherited bone marrow failure syndromes. Clinical and genetic data of 323 patients from the Canadian Inherited Marrow Failure Registry from 2001 to 2014, who had a documented genetic work-up, were analyzed. Cases with pathogenic copy number variants (at least 1 kilobasepairs) were compared to cases with other mutations. Genotype-phenotype correlations were performed to assess the impact of copy number variants. Pathogenic nucleotide-level mutations were found in 157 of 303 tested patients (51.8%). Genome-wide copy number variant analysis by single-nucleotide polymorphism arrays or comparative genomic hybridization arrays revealed pathogenic copy number variants in 11 of 67 patients tested (16.4%). In four of these patients, identification of copy number variant was crucial for establishing the correct diagnosis as their clinical presentation was ambiguous. Eight additional patients were identified to harbor pathogenic copy number variants by other methods. Of the 19 patients with pathogenic copy number variants, four had compound-heterozygosity of a copy number variant with a nucleotide-level mutation. Pathogenic copy number variants were associated with more extensive non-hematological organ system involvement (p = 0.0006), developmental delay (p = 0.006) and short stature (p = 0.04) compared to nucleotide-level mutations. In conclusion, a significant proportion of patients with inherited bone marrow failure syndromes harbor pathogenic copy number variants which were associated with a more extensive non-hematological phenotype in this cohort. Patients with a phenotype suggestive of inherited bone marrow failure syndromes but without identification of pathogenic nucleotide-level mutations should undergo specific testing for copy number variants.Blood disorders: impact of genomic structural variationCopy number variation in patients with inherited bone marrow failure syndromes (IBMFSs) is associated with more severe clinical symptoms. In addition to persistently low levels of red blood cells, white blood cells and/ or platelets, patients with IBMFSs also present varying degrees of physical malformations. Most cases are associated with single base-pair mutations in the DNA sequence, but Canadian researchers led by Yigal Dror at The Hospital for Sick Children in Toronto, have found that whole sections of the genome are deleted or repeated in an important proportion of patients. Those carrying copy number variants (CNV) presented more commonly with developmental delay, short stature and defects in more organ systems, than patients with point mutations. CNV analysis of patients with suspected IBMFSs could aid early disease evaluation and management.