Cord blood-based neonatal genetic screening for thalassemia in Guiyang, China (2015): a cross-sectional study

Background This study aims to assess the carrier frequency and molecular spectrum of thalassemia in neonates from Guiyang, China, a multi-ethnic region with historically limited population-level screening data. Methods This single-center cross-sectional study recruited 1,000 consecutive umbilical cord blood samples from full-term neonates delivered at a tertiary maternal and child health hospital in Guiyang from January 2015 to December 2015. Genetic screening for thalassemia was conducted using commercial gene detection kits. Epidemiological data, including sex, age, ethnicity, place of origin, and routine blood test results, were obtained from the parents of all subjects. High-throughput sequencing was employed to re-examine cord blood samples from neonates whose parents had reduced MCV or a family history of thalassemia. Results Of the 1,000 neonates, 74 were identified as thalassemia carriers, yielding an overall carrier rate of 7.4%. Specifically, 55 cases (5.5%) carried α-thalassemia genes, 18 cases (1.8%) carried β-thalassemia genes, and 1 case (0.1%) was a compound αβ-thalassemia carrier. Among α-thalassemia carriers, the three most frequent deletion genotypes were -α 3.7 (45.45%), --SEA (27.27%), and -α 4.2 (16.36%); non-deletional mutations included α-CS and α-WS. For β-thalassemia carriers, the most common mutations were CD17 (A→T) (44.44%), CD41-42 (-TTCT) (27.78%), and IVS-II-654 (C→T) (16.67%), with one rare domestic mutation (+40–43 [-AAAC]). Of note, 34 carriers were from ethnic minority groups, representing 10 distinct ethnicities. Carrier rates varied significantly by ethnicity: Han 6.28% (43/685), Buyi 17.33% (13/75), Miao 7.79% (6/77), Dong 26.32% (5/19), and Tujia 15.63% (5/32). Intergroup comparisons revealed significantly higher carrier rates among the Buyi, Dong, and Tujia populations compared to the Han population (all P < 0.05, χ 2 test). Conclusion This neonatal cord blood screening study in Guiyang reveals an overall thalassemia carrier rate of 7.4%, with α-thalassemia predominating. The -α 3.7 deletion and CD17 (A→T) mutation were identified as the most frequent α- and β-thalassemia alleles, respectively. Carrier rates were higher in the Buyi, Dong, and Tujia populations compared to the Han population. Further epidemiological studies are needed to confirm the high prevalence of thalassemia in these ethnic groups.