Molecular identification of Vel-negative blood donors in a population from southern Brazil

The Vel antigen is clinically significant and its alloantibody is involved in haemolytic transfusion reactions. This antigen has a high prevalence in the population. The Vel-negative phenotype is the result of a homozygous deletion in the SMIM1 gene (c.64_80del) and hinders the expression of the SMIM1 protein.

A total of 17,472 blood donor samples from the Center for Hematology and Hemotherapy of Santa Catarina State were genotyped targeting the 17-nucleotide (c.64_80del) deletion in the SMIM1 gene. The same method was applied to the siblings of the donors identified as Vel-negative.

The frequency of the c.64_80del17 deletion was 0.90%, and 0.03% of the donors were Vel-negative. In the family study, two individuals were identified as having the homozygous c.64_80del.

These findings underscore the relevance of identifying Vel-negative donors for enhancing rare donor registries and improving transfusion safety.