Misdiagnosis of β-Thalassemia Major Due to Chinese Gγ+(Aγδβ)0-Thalassemia Combined with β0-Thalassemia.

Abstract

δβ-thalassemia is a rare type of thalassemia characterized by increased Hb F levels, including mainly Chinese ^Gγ(^Aγδβ)⁰-thalassemia, Yunnanese ^Gγ(^Aγδβ)⁰-thalassemia, Cantonese ^Gγ(^Aγδβ)⁰-thalassemia in China. Due to the low rate of δβ-thalassemia carriers, there are few reports of δβ-thalassemia combined with β-thalassemia causing β-thalassemia major. Herein, we described the combination of Chinese ^Gγ(^Aγδβ)⁰-thalassemia and β-thalassemia leading to β-thalassemia major in a Chinese patient. Hemoglobin analysis was performed by capillary electrophoresis (CE). Routine genetic analysis was carried out by gap-polymerase chain reaction (Gap-PCR) and PCR and reverse dot blot (PCR-RDB). Multiple ligation-dependent probe amplification (MLPA) was used to detect the large deletion, and Gap-PCR confirmed the deletion. A CE result showed an elevated Hb F level of 98.7% and 11.7% in the proband and her mother, but the proband was diagnosed with β^CD17M/β^CD17M using routine genetic analysis. However, her father was heterozygous for CD17 in β-globin, and her mother was detected as SEA heterozygous. The further analysis presented that the proband had actually missed the diagnosis of Chinese ^Gγ(^Aγδβ)⁰-thalassemia by MLPA and PCR-RDB. Finally, the genotype of the proband was corrected from β^CD17M/β^CD17M to β^CD17M/β^{Gγ(Aγδβ)0}. This is the first report of Chinese ^Gγ(^Aγδβ)⁰-thalassemia combined with β-thalassemia resulting in β-thalassemia major in China. Screening for δβ-thalassemia by Hb analysis could be an effective method.