BIOL209: General Genetics Laboratory
Examining Human Chromosome Disorders
PRE-LAB ASSIGNMENT:
Students are expected to read all pages before coming to the lab to complete the experiments.
Print this entire lab packet and bring it to the laboratory.
Objectives:
After completing this laboratory assignment, students will be able to:
1. Distinguish between the ways to identify chromosomal abnormalities
2. Detect chromosomal abnormalities in a karyotype
Introduction:
Karyotyping is the process of pairing and ordering all the chromosomes of an organism, thus providing a genome-wide snapshot of an individual’s chromosomes. Karyotypes are prepared using standardized staining procedures that reveal characteristic structural features for each chromosome. Clinical cytogeneticists analyze human karyotypes to detect gross genetic changes—anomalies involving several megabases or more of DNA. Karyotypes can reveal changes in chromosome number associated with aneuploid conditions, such as trisomy 21 (Down syndrome). Careful analysis of karyotypes can also reveal more subtle structural changes, such as chromosomal deletions, duplications, translocations, or inversions. In fact, as medical genetics becomes increasingly integrated with clinical medicine, karyotypes are becoming a source of diagnostic information for specific birth defects, genetic disorders, and even cancers. Adapted from: https://www.nature.com/scitable/topicpage/karyotyping-for-chromosomal-abnormalities-298
Experimental Overview:
You and your partner will take on the role of cytogeneticists working in a hospital. Three case studies will be given to you one at a time for review, along with a set of patient chromosomes. You and your partner will arrange the chromosomes into a completed karyotype on a prepared board. After you have successfully constructed the karyotype, you will analyze it and diagnose each patient. Your patient may have a chromosomal abnormalities or a normal karyotype. Be careful and use your observational skills—things are not always as simple as they seem (especially Case K).
Protocol:
1. Obtain a Chromoscan board containing a case study and set of patient chromosomes. Each case study has a Case ID Letter and a unique color. Confirm that the chromosomes match the board.
2. Read the case study found on the left side of the board.
3. On the Cytogenetics Report, record the patient information, including name, case ID, reason for referral, patient age, and source of the cells.
4. To make the process of the karyotype assembly less complex, one of each of the homologous chromosomes is already illustrated on the board. Identify the other homolog and place it on the board in the proper position.
5. Once the karyotype is completed, analyze it for chromosomal anomalies, paying particular attention to chromosome number and structure.
6. Record chromosome number, gender, and chromosomal findings on the Cytogenetics Report.
7. Use the internet to determine the diagnosis of the patient.
8. Return the ALL the chromosome decals to the cryostorage region of the Chromoscan board in RANDOM ORDER, to prepare the board for the next group’s use.
9. Obtain another board and complete the same steps until you have completed a total of 3 case studies.
Instructions for the lab report:
· Assume the role of a Cytogenetist, write out a daily report for the work you accomplished today. It should include but is not limited to:
· A description of how an actual karyotype is constructed. It should be detailed enough that someone else can use your protocol to construct a karyotype.
· DO NOT write the protocol that you followed for this lab.
· Include the three cytogenetic reports that you completed today.
· Assume the role of a Genetic Counselor
· Choose one of the case studies with an abnormal diagnosis and research it in further detail.
· Create notes for the patient and/or the patient’s caregiver with additional implications of the diagnosis, including life expectancy, complications, available treatments, support group information, etc.
· Do not forget to include in-text citations and a “Works Cited” or References page.
Data Sheet:
| Cytogenetics Reports for G-Banded Karyotype-III |
| Patient Name |
Case ID |
Age |
| Why is the patient being referred for karyotyping? |
Source of Cells for Karyotyping
____ Blood
____ Amniocytes
____ Chorionic Villi
____ Other (specify) __________________ |
| Total Number of Chromosomes Observed |
Gender |
| Chromosomal Findings
____ no observable chromosomal abnormalities
____ monosomy (chromosome #____)
____ trisomy (chromosome #____)
____ deletion (chromosome #____, arm _____)
____ insertion (chromosome #____, arm _____)
____ translocation (chromosome #s____ and ____)
____ inversion (chromosome #____, arm(s) _____)
____other (explain)___________________________ |
Diagnosis
Source of Diagnosis |
| Cytogenetics Reports for G-Banded Karyotype-I |
| Patient Name |
Case ID |
Age |
| Why is the patient being referred for karyotyping? |
Source of Cells for Karyotyping
____ Blood
____ Amniocytes
____ Chorionic Villi
____ Other (specify) __________________ |
| Total Number of Chromosomes Observed |
Gender |
| Chromosomal Findings
____ no observable chromosomal abnormalities
____ monosomy (chromosome #____)
____ trisomy (chromosome #____)
____ deletion (chromosome #____, arm _____)
____ insertion (chromosome #____, arm _____)
____ translocation (chromosome #s____ and ____)
____ inversion (chromosome #____, arm(s) _____)
____other (explain)___________________________ |
Diagnosis
Source of Diagnosis |
| Cytogenetics Reports for G-Banded Karyotype-II |
| Patient Name |
Case ID |
Age |
| Why is the patient being referred for karyotyping? |
Source of Cells for Karyotyping
____ Blood
____ Amniocytes
____ Chorionic Villi
____ Other (specify) __________________ |
| Total Number of Chromosomes Observed |
Gender |
| Chromosomal Findings
____ no observable chromosomal abnormalities
____ monosomy (chromosome #____)
____ trisomy (chromosome #____)
____ deletion (chromosome #____, arm _____)
____ insertion (chromosome #____, arm _____)
____ translocation (chromosome #s____ and ____)
____ inversion (chromosome #____, arm(s) _____)
____other (explain)___________________________ |
Diagnosis
Source of Diagnosis |
