Medical Problem Solving, Case 3: Pretzel Syndrome

Overview & Concepts

In a case study-based context, students use microarray data and Chi-square analysis to determine the SNP that is likely causing the condition.  Students then determine the identity of the mutated gene, as well as the function of the normal gene and the type of mutation that causes the syndrome. The activity requires students to have an understanding of 10K Microarrays and SNP as well as Chi-square analysis.  This activity would be a good final application of that knowledge.

Grade Level: 

Concepts Covered: 

OMIM, BLAT, BLAST, microarrays, single nucleotide polymorphisms

Prior Knowledge Required: 

DNA, genes, chromosomes, pedigree, PCR, microarray, SNP, Chi-square analysis

Activity Notes

Days to Teach: 

1-2 50-minute class periods.


Student handout, computers with Internet access, PPT file About The Clinic for Special Children, computer with projection capability

Teaching Tips / Activity Overview: 

  1. Introduce the activity by showing the Power Point about The Clinic for Special Children.
  2. Group students in small groups or pairs and let them work to complete the case study.
  3. Actively monitor students’ progress and address any problems along the way.
  4. When everyone is finished, gather the groups together to reflect on the process and share any insights or questions.


The final discussion is an excellent opportunity to gauge students’ understanding of the process and concepts.


More case studies and the Medical Problem Solving Webquest are also available.


Dr. Erik Puffenberger and Dr. Kevin Strauss at The Clinic for Special Children in Strasburg, PA provided the details for the case study.  Dr. Elizabeth Rice wrote the activity.  Dr. Jamie Blair and Tara Flick reviewed, revised, and edited it.

Academic Standards
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