Mutations in the gene encoding neutrophil elastase in congenital and cyclic neutropenia

Abstract

Congenital neutropenia and cyclic neutropenia are disorders of neutrophil production predisposing patients to recurrent bacterial infections. Recently the locus for autosomal dominant cyclic neutropenia was mapped to chromosome 19p13.3, and this disease is now attributable to mutations of the gene encoding neutrophil elastase (the ELA2 gene). The authors hypothesized that congenital neutropenia is also due to mutations of neutrophil elastase. Patients with congenital neutropenia, cyclic neutropenia, or Shwachman-Diamond syndrome were referred to the Severe Chronic Neutropenia International Registry. Referring physicians provided hematologic and clinical data. Mutational analysis was performed by sequencing polymerase chain reaction (PCR)-amplified genomic DNA for each of the 5 exons of the neutrophil ELA2 gene and 20 bases of the flanking regions. RNA from bone marrow mononuclear cells was used to determine if the affected patients expressed both the normal and the abnormal transcript. Twenty-two of 25 patients with congenital neutropenia had 18 different heterozygous mutations. Four of 4 patients with cyclic neutropenia and 0 of 3 patients with Shwachman-Diamond syndrome had mutations. For 5 patients with congenital neutropenia having mutations predicted to alter RNA splicing or transcript structure, reverse transcriptase-PCR showed expression of both normal and abnormal transcripts. In cyclic neutropenia, the mutations appeared to cluster near the active site of the molecule, whereas the opposite face was predominantly affected by the mutations found in congenital neutropenia. This study indicates that mutations of the gene encoding neutrophil elastase are probably the most common cause for severe congenital neutropenia as well as the cause for sporadic and autosomal dominant cyclic neutropenia.

Clinical implications of ELA2‐, HAX1‐, and G‐CSF‐receptor (CSF3R) mutations in severe congenital neutropenia

“…Heterozygous mutations in ELA2 are the most common genetic abnormality found in approx. 50-60% of CN patients, suggesting a dominant mechanism of action (Dale et al, 2000;Horwitz et al, 2007). However, some cases of CN with ELA2 mutations arise sporadically, consistent with its transmission as an autosomal dominant disorder (Horwitz et al, 2007).…”

The pathology of bone marrow failure

“…The majority of patients have an autosomal dominant trait due mainly to mutations in ELA2, the gene encoding neutrophil elastase. 70,71 The autosomal recessive form (Kostmann syndrome) accounts for about 30% of cases and is due mainly to mutations in the HAX1 gene. 72 In others, the underlying molecular cause is still unknown.…”

“…The total white cell count may be close to normal due to increased numbers of eosinophils and monocytes. 71,73 There can be a mild anaemia and thrombocytosis, 73 and there is an increased risk of transformation to MDS 74 or AML. 75 Rosenberg et al studied 374 patients with SCN and found that the cumulative incidence for MDS ⁄ AML was 21% after 10 years of granulocyte colony-stimulating factor (G-CSF) therapy and 36% after 12 years.…”

Functional interaction between mutations in the granulocyte colony‐stimulating factor receptor in severe congenital neutropenia

“…RNA was extracted from marrow light-density cell fractions. Mutational analysis of CSF3R and ELA2 was performed by sequencing of polymerase chain reaction (PCR)-amplified either genomic DNA or cDNA essentially as described (Ward et al, 1999b;Dale et al, 2000;Dror et al, 2000).…”

“…After ELA2 was found to be associated with SCN (Dale et al, 2000), sequencing of genomic DNA from peripheral blood leucocytes from the previously reported SCN patient (Dror et al, 2000) was performed. This revealed a novel one base pair deletion at nucleotide (delG4981) that resulted in frame shift and premature termination of the mutant neutrophil elastase (A204fs210X).…”