Identification of Three Families Carrying Hb Anti-Lepore Hong Kong Variant in Guangxi, China, and Analysis of Their Hematological Data.

Thalassemia is a single-gene genetic disease with a high incidence in southern China. To prevent and control thalassemia, the most commonly used procedure is hematology testing and hemoglobin (Hb) analysis, followed by thalassemia gene analysis in positive individuals. During routine testing for thalassemia, we identified three individuals with Hb A2 levels of >10.0%. The results of conventional thalassemia gene analysis of these individuals cannot explain this feature, and there is a possibility of carrying novel thalassemia gene variants. Therefore, we collected samples from these three families for further analysis of the thalassemia gene. The research team used multiplex ligation-dependent probe amplification (MLPA) to analyze the three families, and the analysis results showed that their molecular biological characteristics were similar to those of Hb Anti-Lepore Hong Kong (NG_000007.3: g.63210_70621dup). Then, gap-polymerase chain reaction (gap-PCR) and sequencing methods were used for verification, and it was confirmed that the variant carried by these three families was indeed Hb Anti-Lepore Hong Kong. Three individuals carrying both the - -SEA (Southeast Asian) and Hb Anti-Lepore Hong Kong variants were also detected in this study, and these individuals had slightly lower Hb A2 results than those carrying Hb Anti-Lepore Hong Kong alone. Further analyses revealed that the carrier rate of this variant is about 0.03% in the population, thus identifying it as a rare variant.

Comprehensive analysis of thalassemia alleles (CATSA) based on third-generation sequencing is a comprehensive and accurate approach for neonatal thalassemia screening.

Thalassemia is one of the most common and damaging monogenic diseases in the world. It is caused by pathogenic variants of α- and/or ß-globin genes, which disrupt the balance of these two protein chains and leads to α-thalassemia or ß-thalassemia, respectively. Patients with α-thalassemia or ß-thalassemia could exhibit a severe phenotype, with no simple and effective treatment. A three-tiered strategy of carrier screening, prenatal diagnosis and newborn screening has been established in China for the prevention and control of thalassemia, of which the first two parts have been studied thoroughly. The implementation of neonatal thalassemia screening is lagging, and the effectiveness of various screening programs has not yet been demonstrated. In this study, hemoglobin capillary electrophoresis (CE), hotspot testing method, and third-generation sequencing (TGS) were used in the variant detection of 2000 newborn samples, to assess the efficacy of these methods in neonatal thalassemia screening. Compared with CE (249, 12.45 %) and hotspot analysis (424, 21.2 %), CATSA detected the largest number of thalassemia variants (535, 26.75 %), which included 24 hotspot variants, increased copy number of α-globin gene, rare pathogenic variants, and three unreported potentially disease-causing variants. More importantly, CATSA directly determined the cis-trans relationship of variants in three newborns, which greatly shortens the clinical diagnosis time of thalassemia. CATSA showed a great advantage over other genetic tests and could become the most powerful technical support for the three-tiered prevention and control strategy of thalassemia.

The population incidence of thalassemia gene variants in Baise, Guangxi, P. R. China, based on random samples.

OBJECTIVE: Thalassemia is a monogenic genetic disorder with a high prevalence in populations in the southern region of China. The thalassemia gene prevalence rate in the Baise population in China is high, and several rare gene variants have been detected in the population of this region during routine testing by our study group. To accurately reveal the thalassemia gene variants carried by the population in Baise, and to provide a basis for the formulation of thalassemia prevention and control policies in the region, we conducted a more comprehensive study in a randomly selected population. RESULTS: In all, 4,800 randomized individuals were recruited for testing from Baise, and the detection of hot spot thalassemia genetic variants were performed by Gap-PCR and PCR-RDB methods, combined with the relative quantification of homologous fragments and AS-PCR to expand the detection range. The prevalence of thalassemia variants in this population was 24.19%, among which 16.69% of individuals carried α-thalassemia gene variants alone, 5.62% carried ß-thalassemia gene variants alone, and 1.88% carried both variants. CONCLUSIONS: The use of positive primary screening combined with hot spot gene variant detection alone can result in a certain degree of missed detection. In the prevention and control of thalassemia in the region, testing institutions need to pay attention to the detection of rare thalassemia gene variants such as αααanti4.2, αααanti3.7, -α2.4, -α21.9, ß-50, ß-90, and ßIVS-II-5, to provide more accurate genetic counseling advice to subjects.