Audrey Anna Bolyard

Stable long-term risk of leukaemia in patients with severe congenital neutropenia maintained on G-CSF therapy

In severe congenital neutropenia (SCN), long‐term therapy with granulocyte colony‐stimulating factor (G‐CSF) has reduced mortality from sepsis, revealing an underlying predisposition to myelodysplastic syndrome and acute myeloid leukaemia (MDS/AML). We have reported the early pattern of evolution to MDS/AML, but the long‐term risk remains uncertain. We updated a prospective study of 374 SCN patients on long‐term G‐CSF enrolled in the Severe Chronic Neutropenia International Registry. Long‐term, the annual risk of MDS/AML attained a plateau (2·3%/year after 10 years). This risk now appears similar to, rather than higher than, the risk of AML in Fanconi anaemia and dyskeratosis congenita.

Prevalence of mutations in ELANE, GFI1, HAX1, SBDS, WAS and G6PC3 in patients with severe congenital neutropenia

Severe congenital neutropenia (SCN) is a genetically heterogeneous syndrome associated with mutations of ELANE (ELA2), HAX1, GFI1, WAS, CSF3R or G6PC3. We investigated the prevalence of mutations of ELANE in a cohort of 162 SCN patients for whom blood or bone marrow samples were submitted to the North American Severe Chronic Neutropenia Tissue Repository. Mutations of ELANE were found in 90 of 162 patients (55·6%). Subsequently, we conducted an analysis of a subset of 73 of these cases utilising a high throughput sequencing approach to determine the prevalence of other mutations associated with SCN. Among the 73 patients, mutations of ELANE were detected in 28. In the remaining 45 patients with wild type ELANE alleles, five patients had mutations: GFI1 (1), SBDS (1), WAS (1) and G6PC3 (2); no mutations of HAX1 were detected. In approximately 40% of our cases, the genetic basis of SCN remains unknown. These data suggest that for genetic diagnosis of SCN, ELANE genotyping should first be performed. In patients without ELANE mutations, other known SCN‐associated gene mutations will be found rarely and genotyping can be guided by the clinical features of each patient.

Neutrophil elastase mutations and risk of leukaemia in severe congenital neutropenia.

Severe congenital neutropenia (SCN) is a heterogeneous bone marrow failure syndrome predisposing to myelodysplastic syndrome and acute myeloid leukaemia (MDS/AML). We studied 82 North American and Australian SCN patients enrolled in the Severe Chronic Neutropenia International Registry who were on long‐term treatment with granulocyte colony‐stimulating factor and for whom the neutrophil elastase (ELA2) gene was sequenced. There was no significant difference in the risk of MDS/AML in patients with mutant versus wild‐type ELA2: the respective cumulative incidences at 15 years were 36% and 25% (P = 0·96). Patients with either mutant or wild‐type ELA2 should be followed closely for leukaemic transformation.

The diversity of mutations and clinical outcomes for ELANE-associated neutropenia.

Purpose of reviewMutations in the gene for neutrophil elastase, ELANE, cause cyclic neutropenia (CyN) and severe congenital neutropenia (SCN). This study summarized data from the Severe Chronic Neutropenia International Registry (SCNIR) on genotype–phenotype relationships of ELANE mutations to important clinical outcomes. We also summarize findings for ELANE mutations not observed in SCNIR patients. Recent findingsThere were 307 SCNIR patients with 104 distinctive ELANE mutations who were followed longitudinally for up to 27 years. The ELANE mutations were diverse; there were 65 single amino acid substitutions; 61 of these mutations (94%) were ‘probably’ or ‘possibly damaging’ by PolyPhen-2 analysis, and one of the ‘benign’ mutations was associated with two cases of acute myeloid leukemia (AML). All frame-shift mutations (19/19) were associated with the SCN. The pattern of mutations in the SCN versus CyN was significantly different (P < 10–4), but some mutations were observed in both groups (overlapping mutations). The cumulative incidence of severe adverse events, that is, myelodysplasia, AML, stem cell transplantation, or deaths was significantly greater for patients with SCN versus those with CyN or overlapping mutations. Specific mutations (i.e. G214R or C151Y) had a high risk for evolution to AML. SummarySequencing is useful for predicting outcomes of ELANE-associated neutropenia.

Variable clinical presentation of Shwachman-Diamond syndrome: update from the North American Shwachman-Diamond Syndrome Registry.

OBJECTIVES To investigate the range of clinical presentations for Shwachman-Diamond syndrome (SDS) with the long-term goal of improving diagnosis. STUDY DESIGN We reviewed the North American Shwachman-Diamond Syndrome Registry. Genetic reports of biallelic Shwachman-Bodian-Diamond syndrome mutations confirming the diagnosis of SDS were available for 37 patients. RESULTS Neutropenia was the most common hematologic abnormality at presentation (30/37, 81%); however, only 51% (19/37) of patients presented with the classic combination of neutropenia and steatorrhea. Absence of pancreatic lipomatosis on ultrasound or computed tomography scan, normal fecal elastase levels, and normal skeletal survey do not rule out the diagnosis of SDS. SDS was diagnosed in 2 asymptomatic siblings of SDS probands. Twenty-four of 37 patients (65%) had congenital anomalies. CONCLUSION Our cohort reveals a broad range of clinical presentation for SDS. Clues to the underlying diagnosis of SDS included cytopenias with a hypocellular marrow, congenital anomalies, family history, and myelodysplasia with clonal abnormalities frequently found in SDS. Reliance on classic clinical criteria for SDS would miss or delay diagnosis of a significant subset of patients with SDS.

Cyclic neutropenia and severe congenital neutropenia in patients with a shared ELANE mutation and paternal haplotype: evidence for phenotype determination by modifying genes

Cyclic neutropenia (CN) and severe congenital neutropenia (SCN) are disorders of neutrophil production that differ markedly in disease severity. Mutations of the ELANE gene (the symbol recently replacing ELA2) are considered largely responsible for most cases of CN and SCN, but specific mutations are typically associated with one or the other.

Cyclic neutropenia and severe congenital neutropenia in patients with a shared ELANE mutation and paternal haplotype: Evidence for phenotype determination by modifying genes Conflict of interest: Nothing to declare.

Cyclic neutropenia (CN) and severe congenital neutropenia (SCN) are disorders of neutrophil production that differ markedly in disease severity. Mutations of the ELANE gene (the symbol recently replacing ELA2) are considered largely responsible for most cases of CN and SCN, but specific mutations are typically associated with one or the other.

TCIRG1-associated congenital neutropenia.

Severe congenital neutropenia (SCN) is a rare hematopoietic disorder, with estimated incidence of 1 in 200,000 individuals of European descent, many cases of which are inherited in an autosomal dominant pattern. Despite the fact that several causal genes have been identified, the genetic basis for >30% of cases remains unknown. We report a five‐generation family segregating a novel single nucleotide variant (SNV) in TCIRG1. There is perfect cosegregation of the SNV with congenital neutropenia in this family; all 11 affected, but none of the unaffected, individuals carry this novel SNV. Western blot analysis show reduced levels of TCIRG1 protein in affected individuals, compared to healthy controls. Two unrelated patients with SCN, identified by independent investigators, are heterozygous for different, rare, highly conserved, coding variants in TCIRG1.

Somatic mutations and clonal hematopoiesis in congenital neutropenia

Severe congenital neutropenia (SCN) and Shwachman-Diamond syndrome (SDS) are congenital neutropenia syndromes with a high rate of leukemic transformation. Hematopoietic stressors may contribute to leukemic transformation by increasing the mutation rate in hematopoietic stem/progenitor cells (HSPCs) and/or by promoting clonal hematopoiesis. We sequenced the exome of individual hematopoietic colonies derived from 13 patients with congenital neutropenia to measure total mutation burden and performed error-corrected sequencing on a panel of 46 genes on 80 patients with congenital neutropenia to assess for clonal hematopoiesis. An average of 3.6 ± 1.2 somatic mutations per exome was identified in HSPCs from patients with SCN compared with 3.9 ± 0.4 for healthy controls (P = NS). Clonal hematopoiesis due to mutations in TP53 was present in 48% (13/27) of patients with SDS but was not seen in healthy controls (0/17, P < .001) or patients with SCN (0/40, P < .001). Our SDS cohort was young (median age 6.3 years), and many of the patients had multiple TP53 mutations. Conversely, clonal hematopoiesis due to mutations of CSF3R was present in patients with SCN but was not detected in healthy controls or patients with SDS. These data show that hematopoietic stress, including granulocyte colony-stimulating factor, do not increase the mutation burden in HSPCs in congenital neutropenia. Rather, distinct hematopoietic stressors result in the selective expansion of HSPCs carrying specific gene mutations. In particular, in SDS there is enormous selective pressure to expand TP53-mutated HSPCs, suggesting that acquisition of TP53 mutations is an early, likely initiating event, in the transformation to myelodysplastic syndrome/acute myeloid leukemia in patients with SDS.

Abnormal circumferential strain measured by echocardiography is present in patients with Shwachman–Diamond syndrome despite normal shortening fraction

Shwachman–Diamond Syndrome (SDS) is an autosomal recessive disorder characterized by bone marrow failure and exocrine pancreatic dysfunction. Heart failure has been described in patients with SDS. Circumferential strain (εcc) is a measure of cardiac performance that may identify dysfunction when standard measures are normal.