Genetic History Genogram and Interpretation

The Centers for Disease Control and Prevention states that “Too much cholesterol puts you at risk for heart disease and stroke, two leading causes of death in the United States” (CDC, 2021, par.1). Specifically, the low-density lipoprotein cholesterol (LDL-C) is bad for the effective functioning of the cardiovascular system (Balder et al., 2018). High cholesterol level in the blood plasma (> 200 mg/dl) is called hypercholesterolemia, and when it is inherited in the family, it is called familial Hypercholesterolemia (FH) (Martinez-Hervas & Ascaso, 2019). This paper is about the patterns of FH in my family genogram, inheritance of the condition, factors that complicate the interpretation of such a genogram, and the risk of genetic LDL-C.

Patterns of LDL-C

The genogram attached shows that I am female in the third generation, with two male siblings. All my grandparents except my maternal grandfather are diseased, and the rest of the family members in the pedigree are alive. The genogram shows that none of my maternal grandparents had hypercholesterolemia, and consequently, none of their children, including my mother, had it. However, my paternal grandfather had hypercholesterolemia, also documented in his offspring – my father and his only sibling (my paternal aunt). Among my siblings, coming from one parent with hypercholesterolemia and the other one without, only one of us – my brother Andy has LDL-C. It is plausible to say then that my brother Andy has inherited FH from my father, who inherited it from our grandfather. My other brother and I have no hypercholesterolemia by genetic chance because my mother did not have hypercholesterolemia, and there was a genetic risk on her family genogram. Therefore, hypercholesterolemia does go down generations by genetic inheritance.

The Genetic disorder

According to the National Library of Medicine, hypercholesterolemia is an inherited disease (MedlinePlus, 2021). This is supported by studies that consistently trace LDL-C in various genes with recessive inheritance. For instance, Defesche et al. (2017) found that people with LDL-C were children born with abnormally elevated serum cholesterol and have an autosomal dominant mutation in LDLR. Other studies have reported that hypercholesterolemia was mainly caused by genes such as LDL-R, APOB, and PCSK9, which were also identified as recessive (Jarauta et al. (2020); Vrablik et al., 2020). Defesche et al. (2017) findings show that a defective LDL-R is passed on to a child from one parent and a normal one from the other parent in autosomal dominant mutation.

Risk Factors                                                        

In our case, mutations of LDL-R are influenced by genetics where only the father has the condition, giving us a 1/3 chance of getting hypercholesterolemia from a classical Mendelian genetic pattern. In my family genogram, hypercholesterolemia did not skip a generation, indicating a high prevalence of hypercholesterolemia. Based on the findings of Jarauta et al. (2020) and Vrablik et al. (2020), offspring of parents with hypercholesterolemia have mild or severe hypercholesterolemia depending on whether both parents have it. Vrablik et al. (2020) explain that cases of mild hypercholesterolemia are usually undetected or misdiagnosed because of the presence of pseudo-FH subjects in the serum.

In addition, the environmental factors such as lifestyle choices and “a person’s sex, age, and chronic diseases such as diabetes and obesity” (MedlinePlus, 2021, par.7). For instance, all males from mt paternal side have had hypercholesterolemia through the generations. This is confirmed by a recent study that found FH in 47.4% of men and 39.4% of women (Maștaleru et al., 2022). The WebMD also discusses that “the risk from high cholesterol starts in their 20s and goes up with age” (Jaret, 2020, par.1). Therefore, hypercholesterolemia is caused by both genetic and environmental factors.

Conclusion

The genogram from my family indicates the inheritance of hypercholesterolemia. The heredity of the condition has been supported by literature materials that illustrate a genetic connection and environmental risk factors. According to classical Mengerian genetics, there is a 0.33% for my siblings and me to get hypercholesterolemia, which is proved by having only one brother out of us three getting hypercholesterolemia. Sex is also a risk factor as all male members from the paternal side have gotten hypercholesterolemia.

References

Balder, J., Rimbert, A., Zhang, X., Viel, M., Kanninga, R., & van Dijk, F. et al. (2018). Genetics, Lifestyle, and Low-Density Lipoprotein Cholesterol in Young and Apparently Healthy Women. Circulation, 137(8), 820-831. https://doi.org/10.1161/circulationaha.117.032479

CDC. (2021). Cholesterol. https://www.cdc.gov/. Retrieved 22 May 2022, from https://www.cdc.gov/cholesterol/index.htm.

Defesche, J., Gidding, S., Harada-Shiba, M., Hegele, R., Santos, R., & Wierzbicki, A. (2017). Familial hypercholesterolaemia. Nature Reviews Disease Primers, 3(1). https://doi.org/10.1038/nrdp.2017.93

Jarauta, E., Bea-Sanz, A., Marco-Benedi, V., & Lamiquiz-Moneo, I. (2020). Genetics of Hypercholesterolemia: Comparison Between Familial Hypercholesterolemia and Hypercholesterolemia Nonrelated to LDL Receptor. Frontiers In Genetics, 11. https://doi.org/10.3389/fgene.2020.554931

Jaret, P. (2020). High Cholesterol in Men. WebMD. Retrieved 22 May 2022, from https://www.webmd.com/cholesterol-management/high-cholesterol-in-men#:~:text=High%20cholesterol%2C%20also%20called%20hypercholesterolemia,so%20genes%20play%20a%20role.

Martinez-Hervas, S., & Ascaso, J. (2019). Hypercholesterolemia. Encyclopedia Of Endocrine Diseases, 320-326. https://doi.org/10.1016/b978-0-12-801238-3.65340-0

Maștaleru, A., Cojocariu, S., Oancea, A., Constantin, M., Roca, M., & Zota, I. et al. (2022). Genetic Polymorphisms in a Familial Hypercholesterolemia Population from North-Eastern Europe. Journal Of Personalized Medicine, 12(3), 429. https://doi.org/10.3390/jpm12030429

MedlinePlus. (2021). Familial hypercholesterolemia. Medlineplus.gov. Retrieved 22 May 2022, from https://medlineplus.gov/genetics/condition/familial-hypercholesterolemia/#references.

Vrablik, M., Tichý, L., Freiberger, T., Blaha, V., Satny, M., & Hubacek, J. (2020). Genetics of Familial Hypercholesterolemia: New Insights. Frontiers In Genetics, 11. https://doi.org/10.3389/fgene.2020.574474