Severe Congenital Neutropenia (SCN) and Cyclic Neutropenia
About the Disorder | Indications | Specimen | Testing Methodology | Sensitivity | Turnaround Time | Cost | CPT Codes | Shipping | Results | Contact Us
Severe congenital neutropenia (SCN) is a disorder of neutrophil production. The incidence of SCN is approximately 3-4 per million births. Children with SCN typically present with severe neutropenia, fever and recurrent infections of the upper respiratory tract, lungs and skin within the first year of life. Malignant transformation, i.e. myelodysplasia and acute myelogenous leukemia, is a significant risk in individuals with SCN secondary to mutations in ELA2. Treatment with granulocyte colony-stimulating factor (G-CSF) reduces the duration and severity of the neutropenia and improves clinical outcome.
The diagnostic criteria for SCN include:
- Early childhood onset of profound neutropenia (<0.5 × 109/L)
- Recurrent life-threatening bacterial infections
- Promyelocytic maturation arrest in the bone marrow
Cyclic neutropenia is a rare disorder of neutrophil production characterized by periodic cycling of neutrophils, typically at 21 day intervals. Monocytes and reticulocytes cycle out of phase with neutrophils in affected patients. Children with cyclic neutropenia typically present within the first year of life with recurring episodes of fever, skin and oropharangeal infections. Symptoms often improve in adulthood. During the acute phase of the disorder, the neutrophil count may be extremely low, but tends to improve significantly when the child is asymptomatic. Deep tissue cellulitis and bacteremias are the most serious complications of this disorder and may be fatal. Malignant transformation is not a significant risk in individuals with cyclic neutropenia. Treatment with G-CSF reduces the frequency of neutrophil cycling and improves clinical outcome.
SCN is caused by mutations in several genes:
- ELA2—SCN1 and cyclic neutropenia
- HAX1—SCN3 (Kostmann syndrome)
- WAS—X-linked SCN
- GFI1—SCN2
- CSF3R (GCSFR)—somatic mutations in some patients with SCN.
Clinical testing is currently available in our laboratory for mutations in the following threeSCN-related genes:
ELA2: Mutations in the neutrophil elastase gene, ELA2, are the most common cause of SCN, as well as of cyclic neutropenia. ELA2 maps to 19p13.31 and mutations in the ELA2 gene are identified in approximately 35-84% of individuals with SCN. SCN and cyclic neutropenia secondary to mutations in ELA2 are inherited as autosomal dominant conditions. ELA2 consists of five exons and encodes a 218 amino acid protein known as neutrophil elastase. Neutrophil elastase targets bacterial virulence proteins and serves as the cell’s first line of defense against overwhelming bacterial infection. Mutations involving all five exons have been described. Nonsense and frameshift mutations affecting the carboxyl terminus are quite common in SCN patients while missense mutations are seen more commonly in cyclic neutropenia patients. However, there is considerable overlap of genotype with phenotype, even within families.
HAX1: Kostmann syndrome, an autosomal recessive disorder characterized by infantile agranulocytosis, is caused by biallelic mutations in the HAX1 gene. HAX1 maps to 1q21.3 mutations in HAX1have been identified in an minority of individuals with SCN. Mutations in HAX1 have not been reported in association with myelodysplasia or AML; otherwise, the disorder is clinically indistinguishable from ELA2-related SCN. The HAX1 gene consists of seven exons and encodes a 279 amino acid protein which plays a role in neutrophil-specific apoptosis.
WAS: X-linked congenital neutropenia (XLN) is caused by mutations in WAS that result in constitutive activation of WASP. XLN has been described in the presence of various mutations within the Cdc42 binding site. WASP expression in individuals with XLM is comparable to that of normal controls. It is not known if SCN-related mutations in WAS are associated with an increased risk of myelodysplasia or AML, as are mutations in ELA2.
Back to Top
- Confirmation of diagnosis in a symptomatic individual
- Identification of at-risk individuals for future medical management
- Prenatal diagnosis of an at-risk fetus, after identification of a mutation in a proband (by previous arrangement only)
Back to Top
At least 3mL whole blood in purple top (EDTA) tube. Label tube with patient's name, birth date, and date of collection. Buccal swabs are required for analysis in patients who have undergone transplantation and may facilitate DNA isolation in patients undergoing chemotherapy or in individuals with leukopenia. Please call for a free buccal swab collection kit.
Back to Top
Testing is performed by PCR-based sequencing of the entire coding regions and intron/exon boundaries of the ELA2, HAX1 or WAS genes. Testing may be ordered sequentially or in tandem.
Back to Top
The sensitivity of DNA sequencing is over 99% for the detection of nucleotide base changes, small deletions and insertions in the regions analyzed. Gross deletions and insertions, genetic recombinational events and rare, primer site mutations may not be identified using these methods.
Back to Top
1 month
Back to Top
Please call 866-450-4198 for current pricing, billing information or preauthorization of testing.
ELA2 83890, 83898(x5), 83894(x7), 83891(x5), 83904(x11), 83909(x11), 83912
HAX1 83890, 83898(x7), 83894(x9), 83891(x7), 83904(x14), 83909(x14), 84912
WAS 83890, 83898(x7), 83891(X6), 83904(x19), 83894(X8), 83912
Family specific mutation analysis 83890, 83898, 83894, 83891, 83904, 83912
Back to Top
Please enclose test requisition with sample. All information must be completed before sample can be processed. Place samples in Styrofoam mailer and ship at room temperature by overnight Federal Express to arrive Monday through Friday.
Ship to
Cytogenetics and Molecular Genetics Laboratories
3333 Burnet Avenue NRB 1042
Cincinnati, OH 45229
Phone 513-636-4474
Back to Top
Results will be reported to the referring physician or health care provider as specified on the requisition form.
Back to Top
For additional inquiries, contact us:
Phone 513-636-4474
Fax 513-636-4373
Email moleculargenetics@cchmc.org
Back to Top
