Hb Hammersmith [β 42(CD1) Phe→Ser]: Occurrence as a de novo mutation in black monozygotic twins with multiple congenital anomalies

Purpose: To present the occurrence of Hb Hammersmith as a de novo mutation in African-American twins with multiple congenital anomalies. Methods: Standard hematologic methods were used. The presence of an unstable Hb variant was confirmed by brilliant cresyl blue staining and an isopropanol stability test. Hb Hammersmith was confirmed by the sequencing of polymerase chain reaction - amplified β-globin gene. Results: The presence of Hb Hammersmith was confirmed in female monozygotic twins of African-American origin with congenital Heinz body hemolytic anemia and multiple congenital anomalies. The variant occurred as a de novo mutation in the twins. Conclusion: This report describes the occurrence of Hb Hammersmith [B42(CD1)Phe→Ser] in African-American twins. As with the other reported cases, both twins were female. In addition to Heinz body hemolytic anemia, a low arterial O₂ saturation in the proposita was shown by pulse oximetry. Multiple congenital anomalies involving various systems were also found in both twins.