Tehran University Medical Journal (Sep 2007)
Relationship between ELA2 gene mutations, clinical and laboratory parameters in severe congenital and cyclic neutropenia
Abstract
Background: Mutations of ELA2, the gene encoding neutrophil elastase (NE) are known to be associated with cyclic neutropenia (CN) and severe congenital neutropenia (SCN). However, high variability of these mutations has been reported. This study was designed to describe the analysis of the ELA2 gene, clinical manifestations and demographic characteristics in patients with CN and SCN.Methods: A series of 21 patients with CN or SCN were selected, based on SCINR criteria, from the immunology ward of the Pediatric Medicine Center, Tehran, Iran, from March 2004 to August 2005. The ELA2 gene, isolated from blood samples, was analyzed using RT-PCR and automated capillary sequencing. Informed consent was obtained under the tenets of the Helsinki Declaration and the Ethical Committee of the Tehran University of Medical Sciences.Results: Kostmann's syndrome and CN was diagnosed in three and 18 patients respectively. Of all the patients, one or two mutations were found in 18 cases (85.7%), including all three patients with SCN and 15 of the patients with CN. Exons two and four had the most mutations (eight and seven cases, respectively). Seven patients had double mutations in two distinct exons. Overall, 16 different mutations were found. At the time of presentation, the mean age of patients was 13.4 ±17.6 months, ranging from one month to seven years. Overall, 61.9% of patients had consanguineous parents. The mean absolute neutrophil count was 830.5 ±419.4 (150-2000)/mm3. On average, each patient had been admitted to the hospital 2.2 ±1.6 times. The neutrophil counts of the SCN patients were significantly higher than those of the CN patients. However, there was no significant difference in the neutrophil counts between patients with mutations and those without mutations. All patients with SCN had two or more infectious complications, although the prevalence of infectious or non-infectious complications did not correlate with ELA2 mutations or the neutropenic disorders.Conclusion: Mutations in ELA2 appear to play an important role in the phatogenetic mechanisms of CN and SCN. Patients with CN had significantly higher neutrophil counts than SCN patients with CN. Although it possible for the gene encoding neutrophil elastase to have more than one mutation in distinct exons, we found no association between the mutations in ELA2 and their complications in CN and SCN patients.
