Se Gene / Se428
Definition
The original notation for the secretor locus (Se for secretor, se or FUT2*428A for the non-secretor null allele carrying a nonsense mutation at codon 428). The most common non-secretor allele in European and Asian populations.
- Locus
- Secretor gene, FUT2
- Wild-type allele
- Se, produces active secretor enzyme
- Null allele
- se / FUT2*428A, nonsense mutation at codon 428
- Population note
- Most common non-secretor allele in European and Asian populations
- Forensic relevance
- Determines whether ABO antigens appear in body fluids
Common questions
How does the se428 allele actually stop secretion from happening?+
The codon-428 nonsense mutation introduces a premature stop signal in the FUT2 gene, truncating the fucosyltransferase enzyme before it can fold correctly, so the enzyme that would normally add ABO blood group antigens onto secretions in saliva, semen, and other fluids is never produced in functional form.
Why does secretor status matter for forensic serology if DNA typing has replaced ABO grouping?+
Secretor status is now mostly of historical and cold-case interest, since modern casework relies on STR and SNP profiling rather than ABO antigen typing, but it remains relevant when reinterpreting older case records or legacy evidence that was typed using serological methods.
Is a person homozygous for se428 completely unable to secrete ABO antigens?+
Yes, an individual with two copies of a null secretor allele produces no functional enzyme and is a true non-secretor, meaning their saliva and other secretions will not show ABO blood group substances even though their red cells still carry the corresponding antigens.
Related terms
- Blood-Group Substance
- Soluble ABO antigens (A substance, B substance, H substance) present in the body fluids of secretors. Chemically distinct from the glycolipid-bound cell-surface...
- FUT2 Gene
- The Fucosyltransferase 2 gene on chromosome 19q13, encoding the alpha-1,2-fucosyltransferase enzyme responsible for adding fucose to type-1 chain precursors in secretory tissues...
- Inhibition Index
- A quantitative measure of PCR inhibitor burden in a DNA extract, derived from the Ct shift of an internal positive control (IPC)...
- Non-Secretor
- An individual homozygous for non-functional FUT2 alleles who produces no H, A, or B antigen in saliva, semen, or other exocrine secretions,...
- Secretor
- An individual whose ABO blood group antigens are expressed on red blood cells and also released into body fluids such as saliva,...