Big Dye Terminator (BDT) V3.1
Definition
Applied Biosystems' (now Thermo Fisher Scientific's) commercial cycle sequencing kit using four spectrally distinct dichlororhodamine dyes coupled to the four ddNTPs. The standard chemistry for capillary-based Sanger sequencing in forensic mtDNA analysis, specified by SWGDAM and ENFSI guidelines.
- Manufacturer
- Applied Biosystems / Thermo Fisher Scientific
- Chemistry
- Four dichlororhodamine dyes on ddNTPs
- Method
- Capillary-based Sanger cycle sequencing
- Guidelines
- Specified by SWGDAM and ENFSI
Common questions
What is BDT v3.1 chemistry used for in forensic casework?+
It is the standard reagent kit for sequencing mitochondrial DNA, primarily the control region, in samples such as hair shafts or degraded bone where standard STR typing fails.
Why does the kit use four distinct dyes rather than one?+
Each dye is linked to a different dideoxynucleotide terminator, A, C, G, or T, so a single capillary run can distinguish all four bases by dye colour rather than requiring four separate reactions.
Related terms
- 2',3'-Dideoxynucleotide Triphosphate (ddNTP)
- A nucleotide analogue lacking the 3'-hydroxyl group present in normal dNTPs. When incorporated by DNA polymerase into a growing chain, it prevents...
- Cycle Sequencing
- A Sanger sequencing format using a thermostable DNA polymerase and repeated denaturation-annealing-extension cycles (typically 25-35 cycles). Produces exponentially more termination products from...
- EMPOP (ENBISI Mitochondrial Population Database)
- The ENFSI-curated reference database of forensic-grade mtDNA haplotypes used to estimate the frequency of a given control-region profile in a specified population....
- Phred Quality Score
- A logarithmic estimate of base-calling error probability (Phred Q = -10 log10 P). Q20 = 1% error rate; Q30 = 0.1% error...
- rCRS (Revised Cambridge Reference Sequence)
- The standard reference sequence for the human mitochondrial genome (NC_012920.1, 16,569 bp), used as the coordinate system for reporting all forensic mtDNA...
- Sequencing-by-Synthesis (SBS)
- The Illumina detection paradigm: reversibly fluorescent 3'-blocked nucleotides are incorporated one cycle at a time into clonally amplified clusters on a flow...