Accurate and up-to-date data on the frequency of haemoglobinopathies among the populations of Guangxi Zhuang Autonomous Region, where haemoglobinopathies are most endemic in China, are required. In our study, a total of 5789 samples obtained from members of the Han, Zhang, and Yao ethnic groups in six geographical areas of Guangxi Province were analysed systematically in terms of both haematological and molecular parameters. The results presented that the total heterozygote frequency of thalassaemias and other haemoglobinopathies was 24.51%, of which 17.55% was due to alpha-thalassaemia, 6.43% to beta-thalassaemia, 0.38% to structural haemoglobin variants, and 0.16% to delta-thalassaemia. The mutational spectrum among the local population for each type of disorder was described, including the first report on the true prevalence of three silent alpha thalassemia defects, -alpha(3.7)/(4.78%), -alpha(4.2)/(1.61%) and Hb Westmead (alpha(WS)alpha/) (1.57%) and of delta-thalassemia resulting from five novel and two rare mutations never before identified in Chinese individuals. Comparison of the frequencies of alpha-globin mutations among the ethnic groups showed that there was a statistically significant difference between the Han (15.71%) and Zhuang (20.12%), and between the Han (15.71%) and Yao (20.84%) ethnic groups. In addition, we have performed the first extensive study of haematological parameters of the Hb Westmead mutation using a group of Chinese subjects with compound heterozygosity for this variant and an alpha-thalassaemia deletion. The knowledge gained in this study will enable us to estimate the health burden in this high-risk population and to elucidate the various genetic alterations that underlie haemoglobinopathies.

Key Points The prevalence of KLF1 mutations is significantly higher in a thalassemia endemic region of China than in a nonendemic region. KLF1 mutations ameliorate the clinical and hematologic features of β-thalassemia.

Hemoglobinopathies are among the most common autosomal-recessive disorders worldwide. A comprehensive next-generation sequencing (NGS) test would greatly facilitate screening and diagnosis of these disorders. An NGS panel targeting the coding regions of hemoglobin genes and four modifier genes was designed. We validated the assay by using 2522 subjects affected with hemoglobinopathies and applied it to carrier testing in a cohort of 10,111 couples who were also screened through traditional methods. In the clinical genotyping analysis of 1182 β-thalassemia subjects, we identified a group of additional variants that can be used for accurate diagnosis. In the molecular screening analysis of the 10,111 couples, we detected 4180 individuals in total who carried 4840 mutant alleles, and identified 186 couples at risk of having affected offspring. 12.1% of the pathogenic or likely pathogenic variants identified by our NGS assay, which were undetectable by traditional methods. Compared with the traditional methods, our assay identified an additional at-risk 35 couples. We describe a comprehensive NGS-based test that offers advantages over the traditional screening/molecular testing methods. To our knowledge, this is among the first large-scale population study to systematically evaluate the application of an NGS technique in carrier screening and molecular diagnosis of hemoglobinopathies.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the most common X-linked enzymopathies caused by G6PD gene variant. We aimed to provide the characteristics of G6PD deficiency and G6PD gene variant distribution in a large Chinese newborn screening population. We investigated the prevalence of G6PD in China from 2013 to 2017. Then, we examined G6PD activity and G6PD gene in representative Chinese birth cohort to explore the distribution of G6PD gene variant in 2016. We then performed multicolor melting curve analysis to classify G6PD gene variants in 10,357 neonates with activity-confirmed G6PD deficiency, and DNA

Expanded carrier screening (ECS) has been demonstrated to increase the detection rate of carriers compared with traditional tests. The aim of this study was to assess the potential value of ECS for clinical application in Southern China, a region with high prevalence of thalassemia and with diverse ethnic groups, and to provide a reference for future implementations in areas with similar population characteristics. A total of 10,476 prenatal/preconception couples from 34 self-reported ethnic groups were simultaneously tested and analyzed anonymously for 11 Mendelian disorders using targeted next-generation sequencing. Overall, 27.49% of individuals without self-reported family history of disorders were found to be carriers of at least 1 of the 11 conditions, and the carrier frequency varied greatly between ethnic groups, ranging from 4.15% to 81.35%. Furthermore, 255 couples (2.43%) were identified as carrier couples at an elevated risk having an affected baby, sixty-five of which would not have been identified through the existing screening strategy, which only detects thalassemia. The modeled risk of fetuses being affected by any of the selected disorders was 531 per 100,000 (95% CI, 497–567 per 100,000). Our data demonstrate the feasibility of ECS, and provide evidence that ECS is a promising alternative to traditional one-condition screening strategies. The lessons learned from this experience should be applicable for other countries or regions with diverse ethnic groups.