5 Ways to Make 'Inheritance with Pedigrees' A More Approachable Topic

Introduction: Inheritance with Pedigree s

Genetics and inheritance are amazing subjects that have enthralled human beings for almost 200 years now. When Gregor Mendel finally published his results on pea plant experiments after 8 years of intensive work, he laid the foundation for a subject that even he wouldn't have expected to evolve so much through the years. While his results went unrecognized at that time (1865-1900), it was only after the rediscovery of his work in the 1900s that genetics as a subject received wider acceptance and so did Mendel. Now as we all know, he is widely known as the “father of genetics”.

As we know, human beings with their advancing technologies and a better understanding of this subject have been able to overcome many genetic abnormalities and treat many genetic aberrations. No doubt, the research and the concerted efforts of scientists worldwide working on genetics and inheritance patterns of different traits and diseases can further help the human creed to deal with them. This necessitates the development and a clear understanding of this subject in students from the very beginning.

The fundamental principles and concepts of genetics are quite familiar to all students yet their applications and deeper understanding sometimes sound confusing and seem unclear to most. Students often stumble as they are introduced to the different genetics-specific terminologies (dominant-vs-recessive, pedigrees, Punnett squares, segregation-vs-independent assortment, etc) and ideas. We, at Labster, understand this issue faced by most students. We also understand the obstacles faced by educators while explaining these topics.

In this article, we have compiled resources that teachers can use when explaining the topic of ‘inheritance with pedigree’ in their next class. We have highlighted all the major issues encountered by students when dealing with this important tool of genetic analysis. We also list some practical solutions to solve the same. By the end, we’ll convince you why a virtual lab simulation will prove useful not only for your students but also for you as an educator to deliver concepts more efficiently.

3 reasons why ‘Inheritance with Pedigrees’ can be tricky to teach or learn

There are 3 reasons why students are overwhelmed by the topic of Inheritance with Pedigree. Acknowledging these issues is the first step toward making the topic more approachable. 

1. Confusion in basic genetics.

The primary reason why most students face difficulty while dealing with pedigree analyses is a lack of understanding of basic genetics concepts. Many students don’t understand the primary laws of inheritance (Mendel’s laws of heredity). Most students are confused between the 2 laws: ‘The Law of Segregation and ‘The Law of Independent Assortment. Also, many students don’t understand the basic difference between “genes and alleles”, “character and character states/traits”, “autosomal and sex-linked traits”, etc. Without an a priori clear understanding of these typical concepts, it can be an extremely difficult task to comprehend and analyze inheritance patterns using pedigrees.

2. Failure to imbibe the novel tool’s intricacies

Pedigree analysis is a diagrammatic analysis of family relationships. They use a variety of symbols and lines to denote different people and their genetic interrelationships.  Students tend to get confused when using such characters. Since the interrelationships and inheritance patterns are different for ‘autosomal and sex-linked traits’, and ‘dominant and recessive traits’, it further aggravates the issue for the students when using those symbols. And as the number of people in a pedigree keeps increasing, the relationships get more complex and tracing a trait back to “n-number of generations” becomes quite problematic for students amongst the “different lines i.e. relationships”. 

3. Lack of practice and interesting demonstrations 

Solving pedigrees requires students to be utterly attentive and have the shrewdness to relate the presence or absence of a trait/disease amongst different generations. Any deflection at any point in time can make the entire exercise futile. This highlights the importance of engaging tools that can keep students amused and actively involved while educators are explaining how to trace inheritance using pedigrees. Additionally, it becomes difficult for educators to handhold each student through every step of pedigree analysis. This eventually reflects in the lack of practice and commonly encountered hesitation to approach pedigree problems.

5 ways to make ‘Inheritance with Pedigree’ a more approachable topic to understand

To address the complications encountered while teaching the ‘Inheritance with Pedigree’, educators can engage the under-listed solutions in their classes. These can clarify many instrumental aspects of this genetic tool. Not only can they make teaching easier for educators like you but will also make lessons clearer and easier to assimilate for your students.

1. Begin with the basics

It’s of prime importance that the basics of genetics and inheritance are clear to the students. As a first measure, educators should talk in depth about the following topics.

• The idea of genetics and inheritance patterns of different traits and diseases. 
• Mendelian genetics and inheritance (You can use the Mendelian inheritance simulation from Labster to explain it in detail.)
• Idea of the genetic locus 
• Idea of ploidy (monoploid, diploid, etc)
• 3 laws of heredity
• Parent-progeny relationships, sibling relationships
• Idea of genotypes and phenotype
• Difference between genes and alleles
• Difference between character and character states/traits
• Idea of dominant and recessive alleles
• Idea of autosomal and sex-linked traits
• Idea of dominant and recessive traits
• Idea of homozygosity and heterozygosity
• Idea of hybridization and monohybrid-vs-dihybrid crosses

Similarly, you can explain the basics of genetics that are required when solving pedigrees. A solid knowledge system of inheritance concepts can solve half of the issues that students generally encounter when solving complex familial pedigrees. 

Figure: A snippet from Inheritance with Pedigree simulation from Labster. Full simulation is available for School and University/College classes.

2. Explain the meaning of different symbols used in pedigrees

Since several symbols are used in the diagrammatic analysis of pedigrees, it becomes primarily important that students must be able to distinguish and appropriately use those symbols.

Example: 

• Plain circle: Unaffected female
• Plain square: Unaffected male
• Black circle: Affected female
• Black square: Affected male
• Plain diamond: Unknown gender and unaffected 
• Black diamond: Unknown gender and affected 
• Square/Circle/Diamond with numbers inside: Number of different males, females, or unknown gender individual
• Square/Circle/Diamond with a dot inside: Carrier male, female, or unknown gender individual
• 1 line connecting a circle and square: Marriage
• 2 lines connecting a circle and square: Consanguineous marriage
• Roman numerals: Denotation of generation
• Arabic numbers: Individuals/progenies within a given generation (left-most is first born and right-most is last born)

3. Clarify the usage of symbols rather than just introducing them

Educators are encouraged to use different types of pedigrees in their classes where students can see how a variety of symbols and representations can be put to use.

You can explain the importance of each symbol as you proceed.

Example-1: Consanguineous marriage pedigree

Example-2: Carriers in hemophilia pedigree

Similarly, many different pedigrees for autosomal diseases (dominant and recessive), and sex-linked diseases (dominant and recessive) can be explained to students. This will widen their horizons about the usage of different ‘symbols’ and ‘lines’ in the pedigree.

4. Familiarize them with its practical use in genetic diagnosis

Students must be educated about the real-world applications of the pedigree tool when they are being trained to master this technique. This can be encouraging for them to learn it with more passion and enthusiasm. This is also bound to deepen the interest in the subject and can draw more effort when learning it. We list some of the practical uses of pedigrees in the modern world.

• Used by genetic counselors and consultancies to provide prior information to families which might be prone to some genetic conditions (using individual family-specific pedigrees).
• Used to study genealogies for extensively studying human genetics. 
• Used to study genealogies to find the location of genes related to cancer (for example the BRCA1 gene that’s linked to 5 - 10% of all human breast cancers).
• Used to create useful databases for overall medical research.
• It is used to identify carriers of a particular disease (For example hemophilia).

Figure: A snippet from Inheritance with Pedigree simulation from Labster. Full simulation is available for School and University/College classes.

5. Use virtual lab simulations

Pedigree analysis can be very complex to deal with in a single or handful number of classes. This is a topic that can be both difficult to assimilate for students and complex to deliver for educators. 

With a long list of complexities involved in this subject, it comes as a big challenge for educators at both high school and university/college levels. 

To deal with this issue, we at Labster, recommend modern-day educators and teachers use the Inheritance with Pedigree simulation in their next classes. It can help you in delivering an effective session on pedigrees and related terminologies. Your students can actively learn about color blindness and eye color using the basic principles of inheritance and by drawing a virtual pedigree tree. 

As they construct their virtual pedigree, you can explain to them if eye color could be related to color blindness. You can hold more interactive discussions as your students can visualize how different eye colors are passed down through the generations using our simulation. As they also visualize how color blindness is inherited, they can then compare how the 2 pedigree trees are related or if they aren’t, then why?

The 3D simulations will help them better understand the intricacies of pedigrees. Our interactive Inheritance with Pedigree simulation along with gamification elements ensures that your students follow what you are trying to convey in the class. By using this way of active and immersive teaching, our virtual learning platform takes an advent in the field of Science to make the upcoming scientists thorough with the “basics of their respective subjects”. 

You can learn more about the Inheritance with Pedigree simulation from Labster here or get in touch to find out how you can start using virtual labs with your students.

Figure: Snippets from Inheritance with Pedigree simulation from Labster used for virtually building pedigree trees. Full simulation is available for School and University/College classes.