Genetic effect analysis of a rare Hb H hydrops fetalis / 中华地方病学杂志

ABSTRACT

Objective:To analyze the genetic effects of a rare hemoglobin (Hb) H hydrops fetalis [Hb Adana (HBA2: c.179 G>A) complex -- SEA/αα], and provide a reference for clinical diagnosis of non deletion Hb H disease. Methods:Peripheral blood of pregnant women from Medical Genetics Center of Guangdong Maternal and Child Health Hospital and her husbands, fetal umbilical cord blood samples were collected for hematological phenotypes [mean corpuscular volume (MCV), mean corpuscular hemoglobin content (MCH), Hb content] and Hb typing analysis. PCR flow cytometry fluorescence hybridization was used to analyze routine deletions and mutations of α-, β-thalassemia genes, and DNA sequencing was used to analyze mutations.Results:The pregnant women had an MCV of 85.1 fl, MCH of 27.3 pg, and Hb content of 109 g/L; the fetal MCV was 116.3 fl, MCH was 32.6 pg, and Hb content was 28 g/L. Both the pregnant woman and her husband showed no abnormalities in Hb capillary electrophoresis, while the fetus showed Hb Bart's and trace Hb Epsilon4 bands. The results of routine genetic testing for thalassemia showed that the thalassemia genotypes of pregnant women, her husband, and fetus were αα/αα, -- SEA/αα, and -- SEA/αα, respectively. According to DNA sequencing analysis, pregnant women was HBA2: c.179 G>A heterozygous mutation, fetus was HBA2: c.179 G>A mutation. Conclusions:Hydrops fetalis is caused by HBA2: c.179 G>A complex -- SEA/αα. However, this type of mutation is rare in the Chinese population.