Integrated serological and molecular investigation of <scp>ABO</scp> subgroups underlying atypical <scp>ABO</scp> typing in southeastern Brazil

Although ABO subgroups are uncommon, they occur in our population and directly affect blood typing. The results demonstrate the presence of clinically significant variants and highlight the need for vigilance in donor screening, including careful interpretation of typing results, the use of complementary serological testing and molecular analysis when necessary.