The nondeletional types of Hb H disease in Guangxi

Invasive molecular prenatal diagnosis of alpha and beta thalassemia among Hakka pregnant women

This study is a retrospective analysis of the prenatal genetic diagnosis results of fetuses with high risk of major thalassemia to provide information for clinical genetic counseling and to better control the birth of major thalassemia child in Hakka population. Totally, 467 fetuses in at-risk pregnancies were collected from Meizhou people's hospital from January 2014 to December 2017. Genomic DNAs were extracted from peripheral blood of the couples and villus, amniotic fluid or cord blood of the fetuses. DNA-based diagnosis was performed using polymerase chain reaction (PCR) and flow-through hybridization technique. Follow-up visits were done half a year after the fetuses were born. Around 467 fetus at-risk pregnancies were performed prenatal diagnosis. We detected 88 CVS samples, 375 amniocentesis fluid samples and, 4 cord blood samples. The 356 fetuses in α-thalassemia families consisted of 69 (19.38%) with Bart's hydrops syndrome, 20 (5.62%) fetuses with Hb H disease, and 184 (51.68%) fetuses with heterozygote. And the 111 fetuses in β-thalassemia families consisted of 31 (27.93%) thalassemia major, 51 (45.95%) fetuses with heterozygote. There are 13 fetuses with α+β-thalassemia, including 2 cases with severe β-thalassemia. DNA-based testing prenatal diagnosis of thalassemia was found to be highly reliable. Our findings provide key information for clinical genetic counseling of prenatal diagnosis for major thalassemia in Hakka pregnant women. Our work plays an important role in the prevention and control of thalassemia in Hakka population. We will also combine other techniques to further improve our molecular prenatal diagnostic capabilities, including the next-generation sequencing (NGS), Sanger sequencing and MLPA.

Novel technique for rapid detection of alpha-globin gene mutations and deletions

Populations in Southeast Asia and South China have high frequencies of alpha-thalassemia caused by alpha-globin gene mutations and/or deletions. This study was designed to find an efficient and simple diagnostic test for the mutations and deletions. A duplex polymerase chain reaction (PCR)/denaturing high-pressure liquid chromatography (DHPLC) was used to detect the mutations and deletions. A blinded study of 110 samples, which included 92 alpha-thalassemia samples with various genotypes and 18 normal DNA samples, was carried out by the methods. The duplex PCR products of the sample with known Constand spring mutation (CS)/alphaalpha, Quonsze mutation (QS)/alphaalpha, and Weastmead mutation (WS)/alphaalpha DNA showed significantly different profiles, which suggests that DHPLC analysis at 63.8 degrees C can detect potential mutations directly. The DHPLC at 50 degrees C analysis can distinguish the --SEA and nondeletional alleles. The new assay is 100% concordant with the original genotype. In conclusion, the technique including the duplex PCR assay followed by DHPLC analysis can be used to diagnose alpha-thalassemia; this methodology is simple, rapid, accurate, semiautomatic, and high output, and thus, it is suitable for large-scale screening.

Alpha and beta thalassaemia among Chinese children in Guangxi Province, P.R. China: molecular and haematological characterization

We have studied nearly 100 patients with beta-thalassaemia major and 60 patients with Hb H disease who were attending the Haematology Clinic of Guangxi Medical College. Treatment of the patients was limited and only a few patients with beta-thalassaemia major received blood transfusion(s). As a result, the severe anaemia has led to early death at 3-4 years for beta zero-thalassaemia homozygotes, and 8-12 years for beta(+)-thalassaemia homozygotes. Four beta-thalassaemia alleles are responsible for nearly 90% of all beta-thalassaemia chromosomes. This information has resulted in the initiation of a prenatal testing programme at the local level. The patients with Hb H disease maintained a haemoglobin level of 6-10 g/dl and early death was infrequently observed. The --SEA deletion was the major type of alpha-thalassemia-1, while three smaller deletions (-2.7, -3.7 and -4.2 kb) and two nondeletional alpha-thalassaemia determinants (Hbs Constant Spring and Quong Sze) were the alpha-thalassaemia-2 types.