Sequence-Specific Primer PCR (SSP)
Definition
A molecular HLA typing method that uses primer pairs designed to amplify only if a specific allele sequence is present. Results are read as a pattern of positive and negative bands on a gel. SSP gives intermediate resolution and is well-suited to rapid single-sample typing, including forensic and transplant casework.
- Full name
- Sequence-specific primer PCR
- Target
- HLA allele typing
- Read-out
- Positive/negative band pattern on a gel
- Resolution
- Intermediate
- Well suited to
- Rapid single-sample typing, forensic and transplant work
Common questions
Why is SSP resolution described as intermediate rather than high?+
SSP distinguishes alleles based on primer binding at defined sequence positions, which separates broad allele groups reliably but can leave closely related alleles that differ outside the primer binding sites indistinguishable, unlike sequence-based typing which reads the full relevant region.
What makes SSP practical for urgent single-sample situations?+
Each reaction targets one allele or allele group directly and gives a same-day gel result without the batch processing or sequencing runs that other HLA methods need, which matters for time-sensitive contexts like organ transplant matching or a rapid forensic identification request.
How does SSP compare to sequence-based typing (SBT) for forensic paternity or relationship testing?+
SBT reads the actual nucleotide sequence and gives higher-resolution allele calls, which matters most in transplant matching, but SSP's speed and lower cost per sample often make it sufficient for the allele-level resolution needed in routine forensic relationship testing.
Related terms
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- HLA (Human Leukocyte Antigen)
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- Linkage Disequilibrium
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- Paternity Index (PI)
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