Heparinized specimens, severely hemolyzed specimens, frozen, clotted or possibly commingled specimens, blood in non-sterile or leaky containers, mislabeled or inappropriately labeled specimens.
Storage/Transport Temperature
For CHOP Phlebotomy: Samples can be collected throughout the week. Samples collected on weekends or holidays are held in Central Labs and sent to the Genomic Diagnostic Lab the following business day.
For External Clients: Refrigerate sample until shipment. Send the sample at room temperature with overnight delivery for receipt Monday through Friday, optimally within 24 hours of collection.
Please contact the lab (267-426-1447) with questions regarding non-blood specimens.
Volume Required
5 ml whole blood
Minimum Required
3 ml whole blood
Phlebotomy Draw
Yes
Clinical Features
The Sickle Cell Disease Globin Panel is used to determine the molecular cause of sickle cell disease in individuals with both fetal and sickle hemoglobin (Hb S/Hb F) on newborn screen, and for older patients whose test results or phenotype are consistent with sickle cell disease of unknown molecular etiology. This panel can distinguish between sickle cell disease, sickle/beta thalassemia, and sickle cell with persistence of fetal hemoglobin. Concurrent testing for alpha globin gene copy number variants can aid in the clinical treatment and management of the patient.
Sickle cell disease (SCD) is the name of a group of autosomal recessive disorders of red blood cells characterized by chronic hemolytic anemia, vasoocclusive complications, and chronic organ damage [GeneReviews 2021, PMID: 20301551]. The disease is due primarily to a homozygous single base change (c.20A>T) (p.Glu7Val) in the beta globin gene resulting in the production of hemoglobin S (Hb S). There are several genotypes of SCD, the homozygous form (SCD-SS) being the most common. In other variants of SCD, the sickle variant combines with other globin gene variants resulting in forms of the disease that may be as severe as or milder than SCD-SS. The other common variants are SCD-SC, SCD-S/beta-plus thalassemia, and SCD-S/beta-zero thalassemia.
In general, individuals with sickle cell disease who carry alpha globin deletions present milder symptoms, improved hematological parameters, and less dependency on blood transfusion than those without deletions [Stevens 1986, PMID: 2417644; Thomas 1997, PMID: 9120504; Serjeant 2017, PMID: 28689691; Raffield 2018, PMID: 29590102].
Sickle cell with persistence of fetal hemoglobin (Hb S/HPFH) is a rare form of sickle cell disease that is usually associated with high fetal hemoglobin (Hb F) levels and a mild clinical phenotype [Rees 2010, PMID: 21131035; Ngo 2012, PMID: 22017641]. Individuals with Hb S/HPFH genotype are usually asymptomatic and rarely show clinical complications including sickle cell retinopathy, splenic infarct, and acute pain crisis [Talbot 1983, PMID: 6196049; Whyte 2012, PMID: 23281181 Belisário 2016, PMID: 27117574]. Hb S/HPFH can be distinguish from sickle cell disease with a higher hemoglobin level and lower reticulocyte and bilirubin levels [Murray 1988; PMID: 2454649].
Performing Lab
Division of Genomic Diagnostics
Performed
Mon - Fri, 9:00am to 4:00pm
Reported
14 days
Detection Rate
The analytical sensitivity for detecting sequencing variants is ~99%. Sickle cell: This assay will detect 100% of Hb S alleles. The analytical sensitivity is close to 100%. Beta thalassemia: Point mutations in the HBB gene are detected in 95-98% of patients with beta thalassemia. Deletions in the HBB gene are detected in ~2-5% of patients with beta thalassemia. Alpha thalassemia: Deletions in the HBA1 and HBA2 genes are detected in approximately 85-95% of patients with alpha thalassemia.
Utility
The clinical utility of this assay is to support a clinical diagnosis of the disease, facilitate genetic counseling, assess the risk to other first-degree relatives, and facilitate testing of at-risk family members. Molecular confirmation of a diagnosis may help guide recommendations for medical management and provide information regarding prognosis.
We offer concurrent DNA sequence analysis of the beta globin gene (HBB) and copy number analyses of the beta globin gene and alpha globin gene (HBA1 and HBA2) loci which are performed using multiplex ligation-dependent probe amplification assays (MLPA). Sickle cell (Hb S) and beta thalassemia variants are detected by sequencing the beta globin coding region and part of the intervening sequences.
Molecular Testing Notes
The HBB gene is located on chromosome 11p15.5. The inheritance pattern for sickle cell disease and for beta thalassemia is autosomal recessive. Beta thalassemia is caused by decreased or absent beta-globin chain production. The sickle cell mutation (Hb S) is found at codon 7 while beta thalassemia mutations are found throughout the gene.
HBA1 and HBA2 are located on chromosome 16p13.3. Deletion or inactivation of all four alpha-globin alleles results in the most severe form, Hb Bart hydrops fetalis syndrome. Deletion or inactivation of three out of four alpha-globin alleles results in Hb H disease. Deletion or inactivation of two out of four alpha-globin alleles, either in cis (--/alpha, alpha) or in trans (alpha, -/ alpha, -) configuration, results in alpha thalassemia trait. Deletion or inactivation of one out of four alpha-globin alleles results in an alpha thalassemia carrier. Knowing the alpha globin gene copy number in a patient with sickle cell disease can aid in the treatment and management of that individual.
CPT Codes
81269 and 81364
Collection
Collect
Collect whole blood in a purple top (EDTA) tube.
Unacceptable Conditions
Heparinized specimens, severely hemolyzed specimens, frozen, clotted or possibly commingled specimens, blood in non-sterile or leaky containers, mislabeled or inappropriately labeled specimens.
Storage/Transport Temperature
For CHOP Phlebotomy: Samples can be collected throughout the week. Samples collected on weekends or holidays are held in Central Labs and sent to the Genomic Diagnostic Lab the following business day.
For External Clients: Refrigerate sample until shipment. Send the sample at room temperature with overnight delivery for receipt Monday through Friday, optimally within 24 hours of collection.
Please contact the lab (267-426-1447) with questions regarding non-blood specimens.
Volume Required
5 ml whole blood
Minimum Required
3 ml whole blood
Phlebotomy Draw
Yes
Ordering
Clinical Features
The Sickle Cell Disease Globin Panel is used to determine the molecular cause of sickle cell disease in individuals with both fetal and sickle hemoglobin (Hb S/Hb F) on newborn screen, and for older patients whose test results or phenotype are consistent with sickle cell disease of unknown molecular etiology. This panel can distinguish between sickle cell disease, sickle/beta thalassemia, and sickle cell with persistence of fetal hemoglobin. Concurrent testing for alpha globin gene copy number variants can aid in the clinical treatment and management of the patient.
Sickle cell disease (SCD) is the name of a group of autosomal recessive disorders of red blood cells characterized by chronic hemolytic anemia, vasoocclusive complications, and chronic organ damage [GeneReviews 2021, PMID: 20301551]. The disease is due primarily to a homozygous single base change (c.20A>T) (p.Glu7Val) in the beta globin gene resulting in the production of hemoglobin S (Hb S). There are several genotypes of SCD, the homozygous form (SCD-SS) being the most common. In other variants of SCD, the sickle variant combines with other globin gene variants resulting in forms of the disease that may be as severe as or milder than SCD-SS. The other common variants are SCD-SC, SCD-S/beta-plus thalassemia, and SCD-S/beta-zero thalassemia.
In general, individuals with sickle cell disease who carry alpha globin deletions present milder symptoms, improved hematological parameters, and less dependency on blood transfusion than those without deletions [Stevens 1986, PMID: 2417644; Thomas 1997, PMID: 9120504; Serjeant 2017, PMID: 28689691; Raffield 2018, PMID: 29590102].
Sickle cell with persistence of fetal hemoglobin (Hb S/HPFH) is a rare form of sickle cell disease that is usually associated with high fetal hemoglobin (Hb F) levels and a mild clinical phenotype [Rees 2010, PMID: 21131035; Ngo 2012, PMID: 22017641]. Individuals with Hb S/HPFH genotype are usually asymptomatic and rarely show clinical complications including sickle cell retinopathy, splenic infarct, and acute pain crisis [Talbot 1983, PMID: 6196049; Whyte 2012, PMID: 23281181 Belisário 2016, PMID: 27117574]. Hb S/HPFH can be distinguish from sickle cell disease with a higher hemoglobin level and lower reticulocyte and bilirubin levels [Murray 1988; PMID: 2454649].
Performing Lab
Division of Genomic Diagnostics
Performed
Mon - Fri, 9:00am to 4:00pm
Reported
14 days
Detection Rate
The analytical sensitivity for detecting sequencing variants is ~99%. Sickle cell: This assay will detect 100% of Hb S alleles. The analytical sensitivity is close to 100%. Beta thalassemia: Point mutations in the HBB gene are detected in 95-98% of patients with beta thalassemia. Deletions in the HBB gene are detected in ~2-5% of patients with beta thalassemia. Alpha thalassemia: Deletions in the HBA1 and HBA2 genes are detected in approximately 85-95% of patients with alpha thalassemia.
Utility
The clinical utility of this assay is to support a clinical diagnosis of the disease, facilitate genetic counseling, assess the risk to other first-degree relatives, and facilitate testing of at-risk family members. Molecular confirmation of a diagnosis may help guide recommendations for medical management and provide information regarding prognosis.
We offer concurrent DNA sequence analysis of the beta globin gene (HBB) and copy number analyses of the beta globin gene and alpha globin gene (HBA1 and HBA2) loci which are performed using multiplex ligation-dependent probe amplification assays (MLPA). Sickle cell (Hb S) and beta thalassemia variants are detected by sequencing the beta globin coding region and part of the intervening sequences.
Molecular Testing Notes
The HBB gene is located on chromosome 11p15.5. The inheritance pattern for sickle cell disease and for beta thalassemia is autosomal recessive. Beta thalassemia is caused by decreased or absent beta-globin chain production. The sickle cell mutation (Hb S) is found at codon 7 while beta thalassemia mutations are found throughout the gene.
HBA1 and HBA2 are located on chromosome 16p13.3. Deletion or inactivation of all four alpha-globin alleles results in the most severe form, Hb Bart hydrops fetalis syndrome. Deletion or inactivation of three out of four alpha-globin alleles results in Hb H disease. Deletion or inactivation of two out of four alpha-globin alleles, either in cis (--/alpha, alpha) or in trans (alpha, -/ alpha, -) configuration, results in alpha thalassemia trait. Deletion or inactivation of one out of four alpha-globin alleles results in an alpha thalassemia carrier. Knowing the alpha globin gene copy number in a patient with sickle cell disease can aid in the treatment and management of that individual.
