The prevalence and spectrum of STEAP3 mutations in the Chinese population. (A) Study design and study outcomes. A total of 3205 individuals from 2 representative regions (southern and northern China) were studied to document the incidence of STEAP3 mutations. Southern Chinese population: 3 groups of 2105 subjects from Guangxi where thalassemias are endemic included 1238 normal subjects (group A), 557 α-thalassemia carriers (group B), and 310 individuals with hemoglobin H (HbH) disease samples (group C). STEAP3 mutations occurred at similar frequencies among these 3 groups (P = .720), confirming a high prevalence of STEAP3 mutations in southern China. The high prevalence of STEAP3 mutations was also noted in 1100 normal individuals recruited from the Shandong Province in northern China. All 179 mutant alleles detected in these 2 populations were used to assess the spectrum of STEAP3 mutations. (B) Domains in the gene structure of STEAP3 are indicated by the different color boxes and the untranslated regions are delineated by the solid black line. Sixteen functional STEAP3 mutations are shown below the map and 8 novel mutations are marked with an asterisk. Twenty-eight neutral mutations (4 variants in the 5′UTR and 23 missense mutations in the coding regions) are shown with black dots above the map and are presented in supplemental Table 1. The eSNP (rs6721852) in the STEAP3-C2orf76 intergenic region is also indicated at the right.