DIY PCR and SNP Genotype Correlation Project

ISEF Category: Cellular and Molecular Biology

Subcategory: Molecular Biology  ·  Difficulty: Advanced  ·  Setup: University Lab  ·  Time: Full Year

The Hook

Your DNA can hint at traits, but your job is to test that link with data. A cheap gel can separate DNA pieces like a sieve sorts sand. A SNP panel can turn one tiny letter change into a measurable research question. If you do it well, you are not just looking at genes, you are testing how well genes predict a real trait in your school community.

What Is It?

This project asks a simple question with real science behind it: can a small set of genetic markers help explain a self-reported trait? A SNP, or single nucleotide polymorphism, is one DNA letter that differs between people. Some markers are tied to traits like lactose persistence, while others act as proxies for copy number or broader biology. Your goal is to compare genotype, which is the DNA result, with phenotype, which is the trait you can observe or survey.

Agarose gel electrophoresis separates DNA fragments by size. Think of it like running pebbles through a mesh. Smaller pieces move farther. In your project, the gel gives you a visual readout of PCR products or fragment patterns. The science comes from matching those bands to a clear scoring system, then comparing that score with phenotype data using statistics, not guesses.

Why This Is a Good Topic

This is a strong science fair topic because it has a clear variable, a measurable output, and a real-world connection to human genetics. You can compare genetic patterns with a trait that people can report or measure, such as lactose tolerance, starch-related habits, or a simple family history survey. The project teaches you how molecular biology, data quality, and statistics work together. It also gives you room to make the study stronger by improving controls, sample handling, or analysis.

Research Questions

• How does genotype at the MCM6 lactase persistence marker relate to self-reported lactose tolerance in a school cohort?
• What is the effect of AMY1 copy-number proxy category on self-reported starch-related eating comfort or digestive response?
• Does gel band quality differ between sample types or collection methods in a student PCR workflow?
• To what extent do genotype and phenotype agree for a small panel of personal SNP markers?
• Which marker gives the strongest phenotype association after adjusting for age, sex, and ancestry self-report?
• How does adding more careful phenotype scoring change the strength of the genotype-phenotype association?

Basic Materials

• Saliva collection tubes or cheek swab kits with consent forms.
• PCR-grade DNA extraction supplies or mailed genotyping kit service.
• Thermocycler access through a university or school partner.
• Agarose powder and electrophoresis chamber.
• Buffer system approved by your lab supervisor.
• DNA stain or low-cost safe dye approved by your lab supervisor.
• Micropipettes and filter tips.
• DNA ladder with known fragment sizes.
• Blue-light transilluminator or gel imaging system.
• Data sheet for phenotype survey responses.
• Digital kitchen scale or laboratory balance for gel prep.
• Ruler or image analysis software for band measurement.

Advanced Materials

• Capillary electrophoresis access for higher-resolution fragment sizing.
• qPCR system for copy-number estimation.
• SNP genotyping assay or PCR primer set validated by a molecular biology lab.
• Genomic DNA quantification instrument such as a fluorometer.
• Negative and positive control DNA samples.
• Bioinformatics workstation for genotype calling and data cleaning.
• Statistical software for association testing.
• Secure data storage for de-identified participant records.
• Institutional review materials for human subject approval.
• Gel documentation system with fixed exposure settings.

Software & Tools

• ImageJ: Measures gel band position and intensity so you can compare samples consistently.
• R: Runs association tests, plots genotype and phenotype patterns, and handles basic statistics.
• Python: Cleans survey data, merges genotype tables, and automates plotting.
• Excel: Organizes sample IDs, phenotype scores, and gel notes in a simple spreadsheet.
• PubMed: Helps you find review articles and primary papers on lactase persistence, AMY1, and SNP analysis.

Experiment Steps

1. Define one trait and one or two genetic markers so your study stays focused.
2. Build a participant plan that includes consent, de-identification, and a clear phenotype survey.
3. Choose a genotyping method and confirm that your marker assay can separate the groups you want to compare.
4. Design controls that help you spot failed DNA extraction, failed amplification, or band calling errors.
5. Set up a scoring system for gel results and phenotype categories before you see the data.
6. Plan your statistics so you can test association strength, not just list matching examples.

Common Pitfalls

• Mixing up phenotype labels, which breaks the genotype-to-trait comparison before analysis starts.
• Using a gel image from changing light or exposure settings, which makes band calls inconsistent across runs.
• Picking a marker with weak or unclear trait linkage, which gives you noisy results and little interpretable signal.
• Forgetting ancestry or family background can affect allele frequencies, which can make a school cohort look more linked than it really is.
• Letting sample IDs get separated from consent and survey records, which ruins de-identification and data traceability.

What Makes This Competitive

A competitive version of this project does more than match bands to survey answers. It uses clean controls, preplanned scoring rules, and a real statistical test for association. Strong projects also explain limits, like ancestry structure, small sample size, and self-report bias. If you can compare more than one marker, or test whether one marker predicts a trait better than another, your project starts to look much stronger.

Project Variations

• Swap the school cohort for a family-based study that compares genotype and phenotype within siblings or parents.
• Replace the survey trait with a measured phenotype, such as lactose response questionnaires or starch preference scoring.
• Compare standard agarose gels with a higher-resolution fragment-sizing method to see which gives cleaner genotype calls.

Learn More

• NCBI Gene and dbSNP: Use these databases to check gene function, known SNPs, and reference variants at the NIH site.
• PubMed: Search review articles on lactase persistence, AMY1 copy number, and genotype-phenotype association studies.
• NIH Genetic Testing Registry: Look for descriptions of genetic tests and how targets are measured in research and clinical settings.
• NCBI Bookshelf: Read free genetics and molecular biology chapters that explain PCR, gels, and variant interpretation.
• MIT OpenCourseWare, Biology courses: Find free molecular biology lecture materials and problem sets for PCR and DNA analysis.
• Nature Education Scitable: Read accessible articles on genetic variation, inheritance, and molecular techniques.