title: Application of an expanded multiplex genotyping assay for the simultaneous detection of Hemoglobin Constant Spring and common deletional alpha-thalassemia mutations.
abstract: Hemoglobin Constant Spring (HbCS) is the most common nondeletional alpha-thalassemia variant causing HbH disease, making its detection crucial in populations at risk. Universal newborn screening for HbH is carried out in California. Identification of alpha-thalassemia genotypes responsible for HbH and HbH-CS requires rapid, accurate and cost-effective genotyping methods suitable for population screening. We incorporated the HbCS mutation into our existing seven-plex genotyping assay for common alpha-thalassemia deletions. To assess the feasibility and diagnostic utility of this expanded multiplex gap-PCR assay, we determined genotypic frequencies of HbCS in samples referred for alpha-thalassemia testing between 1 January 2006 and 31 December 2008. During the 3-year study period, 1436 samples were genotyped for alpha-thalassemia. HbH-CS accounted for 23 (13%) of the 176 cases of HbH disease identified. In a subset of 145 newborns referred by the California NBS program with an elevated Hb Bart's level at birth, HbH disease was confirmed in 134 (93%) and HbH-CS identified in 13 (10%) of these. This expanded genotyping assay has proven to be a rapid, reliable and clinically useful diagnostic tool for the detection of HbH-CS disease.
authors.affiliation: Hemoglobinopathy Reference Laboratory, Children's Hospital & Research Center Oakland, 747 52nd Street, Oakland, CA 94609, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Kidd
authors.forename: M
authors.initials: M
authors.lastname: Azimi
authors.forename: B
authors.initials: B
authors.lastname: Lubin
authors.forename: E
authors.initials: E
authors.lastname: Vichinsky
authors.forename: C
authors.initials: C
authors.lastname: Hoppe
mesh_terms: D002140:California; D005500:Follow-Up Studies; D005838:Genotype; D006455:Hemoglobins, Abnormal / Q000235:genetics*; D006801:Humans; D007231:Infant, Newborn; D016133:Polymerase Chain Reaction / Q000379:methods*; D017384:Sequence Deletion / Q000235:genetics*; D017085:alpha-Thalassemia / Q000097:blood / Q000175:diagnosis / Q000235:genetics*
chemical_list: D006455:Hemoglobins, Abnormal; C035541:Hemoglobin Constant Spring