Hb Hammersmith [beta 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 unstabl e Hb Variant was confirmed by brilliant cresyl blue staining and an isoprop anol stability test. Hb Hammersmith was confirmed by the sequencing of poly merase chain reaction-amplified beta-globin gene. Results: The presence of Hb Hammersmith was confirmed in female monozygotic twins of African-American origin with congenital Heinz body hemolytic anem ia and multiple congenital anomalies. The variant occurred as a de novo mut ation 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, bo th twins were female. In addition to Heinz body hemolytic anemia, a low art erial O-2 saturation in the proposita was shown by pulse oximetry. Multiple congenital anomalies involving various systems were also found in both twi ns.