Strong Positive Dichlorophenolindophenol Precipitation Suggests Hb Dhonburi (or Hb Neapolis) (HBB: c.380T>G) Inheritance in a Couple at Risk for Severe β-Thalassemia.

Pinyaphat Khamphikham, Supachai Sakkhachornphop, Saipin Pongsatha, Sakorn Pornprasert

Hemoglobin 2022 May

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Hb Dhonburi (also known as Hb Neapolis) (HBB: c.380T>G) is an unstable hemoglobin (Hb) variant that cannot be detected by high performance liquid chromatography (HPLC) or capillary electrophoresis (CE) in routine laboratory diagnosis. This could lead to prenatal misdiagnosis unless a molecular analysis is applied. Here, we report a Thai couple with a positive result for the dichlorophenolindophenol precipitation (DCIP) screening test. After routine laboratory investigation, the female was diagnosed with heterozygous Hb E (HBB: c.79G>A) during pregnancy; however, the male, whose case we present herein, was suspected to carry a rare heterozygous β-thalassemia (β-thal). Therefore, they were designated as a couple at-risk for having a fetus with a serious thalassemia genotype: compound heterozygosity for Hb E with β-thal (Hb E/β-thal). Based on the result of the DCIP test, his DNA was sequenced for a causative mutation and revealed heterozygosity for a rare Hb variant, Hb Dhonburi. Theoretically, this couple was not at risk for Hb E/β-thal. Furthermore, this case demonstrates for the first time that in addition to a common Hb variant, i.e. Hb E, Hb Dhonburi (Hb Neapolis) also gives positive DCIP results, even in the heterozygous state.

Citation

Pinyaphat Khamphikham, Supachai Sakkhachornphop, Saipin Pongsatha, Sakorn Pornprasert. Strong Positive Dichlorophenolindophenol Precipitation Suggests Hb Dhonburi (or Hb Neapolis) (HBB: c.380T>G) Inheritance in a Couple at Risk for Severe β-Thalassemia. Hemoglobin. 2022 May;46(3):184-186