Epidemiological Survey of Hemoglobinopathies Based on Next-Generation Sequencing Platform in Hunan Province,China

Objective This study was aimed at investigating the carrier rate of,and molecular variation in,α-andβ-globin gene mutations in Hunan Province.Methods We recruited 25,946 individuals attending premarital screening from 42 districts and counties in all 14 cities of Hunan Province.Hematological screening was performed,and molecular parameters were assessed.Results The overall carrier rate of thalassemia was 7.1%,including 4.83%forα-thalassemia,2.15%forβ-thalassemia,and 0.12%for bothα-andβ-thalassemia.The highest carrier rate of thalassemia was in Yongzhou(14.57%).The most abundant genotype ofα-thalassemia andβ-thalassemia was-α^(3.7)/αα(50.23%)andβ^(IVS-Ⅱ-654)/β^(N)(28.23%),respectively.Fourα-globin mutations[CD108(ACC>AAC),CAP+29(G>C),Hb Agrinio and Hb Cervantes]and sixβ-globin mutations[CAP+8(C>T),IVS-Ⅱ-848(C>T),-56(G>C),beta nt-77(G>C),codon 20/21(-TGGA)and Hb Knossos]had not previously been identified in China.Furthermore,this study provides the first report of the carrier rates of abnormal hemoglobin variants andα-globin triplication in Hunan Province,which were 0.49%and 1.99%,respectively.Conclusion Our study demonstrates the high complexity and diversity of thalassemia gene mutations in the Hunan population.The results should facilitate genetic counselling and the prevention of severe thalassemia in this region.

Genome-wide detection of additional fetal chromosomal abnormalities by cell-free DNA testing of 15,626 consecutive pregnant women

Cell-free DNA(cfDNA) testing for common fetal trisomies(T21, T18, T13) is highly effective. However, the usefulness of cfDNA testing in detecting other chromosomal abnormalities is unclear. We evaluated the performance of cfDNA testing for genome-wide abnormalities, and analyzed the incremental yield by reporting extra abnormalities. We performed genome-wide cfDNA testing in 15,626 consecutive pregnancies prospectively enrolled in this study. cfDNA testing results were reported and counseling was given depending on the presence of extra chromosomal abnormalities. cfDNA testing identified 190 cases(1.2%)of chromosomal abnormalities including 100 common trisomies and 90 additional abnormalities. By expanding the cfDNA reporting range to genome-wide abnormalities, the false positive rate increased to 0.39%(P<0.001) and positive predictive value(PPV) was reduced to 65.58%(P=0.42). However, the detection yield increased from 0.44% to 0.65%(P=0.014), and cfDNA testing detected 38.61%(39/101) additional abnormalities with no ultrasound and biochemical screening findings. cfDNA testing outperformed biochemical screening by showing 60 times higher true positive rate and fewer false negative results.Genome-wide cfDNA testing significantly increased the diagnostic yield by detecting extra abnormalities, especially those without diagnostic indications. Genome-wide cfDNA testing has fewer false positive and false negative results compared with biochemical screening.