Dubai Police Genome Center

Select the sample to work on Sample —

🔬 Case brief — work as a group

A blood sample arrived at the Genome Center with no name attached. You can't see the donor — but their DNA can describe them. Six positions that influence visible traits have been sequenced. Each is a SNP (single-nucleotide polymorphism): a spot where people commonly differ by one base.

As a group, read the sequencing trace at each SNP and agree on the donor's genotype (the two alleles they carry). When you've agreed on all six, press “Show our group's answers” for a summary to report to your instructor — who holds the key, will tell you if you're right, and will reveal what the donor looks like.

Look at each chromatogram. The arrow marks the SNP position.
One clean peak at the arrow → homozygous (e.g. A/A).
Two overlapping half-height peaks at the arrow → heterozygous (e.g. A/G).
Pick the genotype button that matches what you see for each SNP.

Peak colours (standard Sanger): A green C blue G dark T red

Tip for heterozygotes: at the SNP you'll see two shorter peaks stacked at the same position instead of one tall peak — the visual signature of a heterozygous site in Sanger sequencing.

🧬 Sequencing traces — agree on the genotype at each SNP

📋 Your group's answers — Sample

Read these to your instructor. Nothing here is graded — your instructor confirms which calls are right.

🔑 Answer key — Sample instructor only

🪪 The donor looks like… predicted

Predictions come from a simplified teaching model using a handful of major-effect SNPs. Real forensic DNA phenotyping (e.g. HIrisPlex-S) uses 41+ markers and reports probabilities, not certainties.