Gregor Mendel’s findings established the principles of genetics, propelling research and the development of technology to increase our understanding of genetic disorders. Mendel’s discoveries help explain the inheritance of Mendelian disorders which allows us to assess genetic risk factors and benefits for future generations. In addition, studying inheritance patterns of Mendelian disorders gives deeper insight into the genetic makeup and mechanism of inheritance of complex diseases.

Genetic tests such as carrier screening allow us to recognize genetic risk factors for Mendelian disorders (2). Genetic tests help determine an individual’s susceptibility to diseases and disorders. Carrier screening specifically is a type of genetic test that is used to find the types of alleles that an asymptomatic person has for specific diseases based on ethnicity and family history (2). Genetic tests such as carrier screening are only possible due to Mendel’s discoveries. Carrier screening is only effective for Mendelian disorders that follow an autosomal recessive pattern of inheritance (2). The three main laws of genetic inheritance: the law of segregation, the law of independent assortment, and the law of dominance, can be applied to the results of a genetic test to assess risks for the individual and their future children (5). Through this knowledge, individuals would be able to manage or prevent diseases more actively by screening for the disease at earlier ages or avoiding its risk factors.

Mendel’s work laid the foundation to uncover the mechanisms of Mendelian disorders, such as sickle cell anemia. Sickle cell anemia is an example of a Mendelian disorder that follows an autosomal recessive pattern of inheritance and expresses incomplete dominance (1, 8). This allows carriers of the disease to be mostly asymptomatic. Additionally, carriers of sickle cell anemia benefit from having one copy of the sickle cell allele because they are protected from malaria (4). This understanding of the benefits of heterozygous individuals for sickle cell anemia were made possible by Mendel’s discoveries. Mendel’s law of dominance laid the foundation necessary to uncover more complex forms of dominance, such as incomplete dominance, that deepen our understanding of Mendelian disorders (6).  

Much like the discovery of incomplete dominance, Mendel’s work paved the road for much of modern research which is conducted by altering or controlling the alleles of organisms to understand diseases. In accordance with Mendel’s pea plant experiment, researchers choose to breed specific animals together based on genotype to create offspring that serve as a model for diseases. This allows us to not only figure out inheritance patterns and discover disease-associated alleles, but create avenues to cure such disorders through research.

Utilizing our knowledge of inheritance patterns for Mendelian disorders provides deeper understanding of the genetic factors that affect the inheritance of complex diseases. Parkinson’s disease (PD) – a complex disease– does not follow a Mendelian pattern of inheritance (10). PD is a nervous system disorder that affects motor function (9). Although it is currently unclear exactly how individuals develop PD, studies have proven that genetic factors do indeed play a role (3, 7). Since the discovery of mutations that caused PD in 1997, specific genes with Mendelian inheritance patterns that affect PD have been identified (3, 7). In fact, some forms of PD are inherited and monogenic (7). With each identification of a gene that affects monogenic forms of PD, a puzzle piece to understanding the heritability of the disease is gained, further increasing our ability to assess an individual’s susceptibility to the disease (7). 

Gregor Mendel’s discoveries led to the formation of the laws of genetic inheritance, which allow us to understand Mendelian inheritance. Importantly, Mendel’s laws opened the door for scientists to discover more mechanisms of inheritance for diseases, such as incomplete dominance. This knowledge enables us to create tools for better health such as genetic tests and deepens our understanding of Mendelian disorders like sickle cell anemia. Furthermore, knowledge of Mendelian disorders led to the discovery and research of the genetic components of complex diseases. Overall, studying mendelian disorders shows us that each disease has an underlying genetic basis. Therefore, from PD to cancer or many other diseases, research into the genetic foundations of such disorders deepens our understanding of the workings of such diseases and endeavors to create cures for many who suffer from them. The broad benefits of such research, made possible by Mendel’s work, give credence to his title as the “Father of Genetics”.

1. Alliance, G. (2010, February 17). Classic mendelian genetics (patterns of inheritance). Understanding Genetics: A District of Columbia Guide for Patients and Health Professionals. Retrieved March 2, 2022, from ncbi.nlm.nih.gov/books/NBK132145/

2. Bajaj, K., & Gross, S. J. (2014, September 15). Carrier screening: Past, present, and future. Journal of Clinical Medicine. Retrieved March 2, 2022, from ncbi.nlm.nih.gov/pmc/articles/PMC4449659/

3. Domingo, A., & Klein, C. (2018, January 8). Genetics of Parkinson disease. Handbook of Clinical Neurology. Retrieved March 2, 2022, from sciencedirect.com/science/article/abs/pii/B9780444632333000142?via%3Dihub

4. Editorial Team. (2021, August 18). Malaria risk & sickle cell. Sickle. Retrieved March 2, 2022, from sickle-cell.com/clinical/malaria

5. The Editors of Encyclopaedia Britannica. (2011). Mendelian inheritance. Encyclopædia Britannica. Retrieved March 2, 2022, from britannica.com/science/Mendelian-inheritance

6. Frizzell, M. A. (2013, May 1). Incomplete dominance. Brenner's Encyclopedia of Genetics (Second Edition). Retrieved March 2, 2022, from sciencedirect.com/science/article/pii/B9780123749840007841

7. Hernandez, D. G., Reed, X., & Singleton, A. B. (2016, April 18). Genetics in parkinson disease: Mendelian versus non-mendelian inheritance. Journal of neurochemistry. Retrieved March 2, 2022, from ncbi.nlm.nih.gov/pmc/articles/PMC5155439/

8. Kraus, D. (2012). 12 foundation. CK-12. Retrieved March 2, 2022, from flexbooks.ck12.org/cbook/ck-12-middle-school-life-science-2.0/section/3.14/primary/lesson/non-mendelian-inheritance-ms-ls/

9. U.S. Department of Health and Human Services. (n.d.). Parkinson's disease. National Institute on Aging. Retrieved March 2, 2022, from nia.nih.gov/health/parkinsons-disease

 
10. Motulsky, A. G. (2006, February). Genetics of complex diseases. Journal of Zhejiang University. Science. B. Retrieved March 2, 2022, from ncbi.nlm.nih.gov/pmc/articles/PMC1363767/