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.

Certain beta globin gene mutations produce a thalassemia major phenotype in the heterozygous state. While most such patients have thalassemia intermedia, we describe a young Guatemalan child with a de novo mutation in the beta globin gene, codon 31 T --> G (Hemoglobin Hakkari), who developed severe anemia at the age of 10 months and remains transfusion-dependent. The substitution of B13 leucine with arginine in the beta globin results in alteration of a critical heme contact point resulting in an extremely unstable variant hemoglobin and a clinical picture that is characterized by ineffective erythropoiesis and numerous intracytoplasmic inclusions within the erythrocyte precursors of the bone marrow. .