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Autosomal Diseases: Recessive and Dominant

This demonstrates dominant and recessive inheritance (dominant on the left and recessive on the right)


An autosomal disease is where one of the 22 non-sex chromosomes are affected by a mutation in the DNA. The inheritance of this disease can be either dominant or recessive. If it is dominant, it means that you only need the “bad gene” from one parent in order to be affected. If it is recessive, it means that you need the abnormal gene from both parents in order to be affected. The method of inheritance controls the probability of occurrence. Dominant makes an autosomal disease easier to occur rather than recessive. While the probability of inheriting an autosomal recessive disease is 25%, the probability for dominant stands at 50%. This type of genetic disease can affect both genders and can leave a huge impact on the patient.

In one of my case studies, I came across a patient diagnosed with an autosomal dominant disease. In this case, a girl’s uncle was diagnosed with Huntington’s disease, a neurodegenerative disorder. This disease is extremely rare yet it is an autosomal dominant disorder. This means that the patient most likely have had one parent with the abnormal gene. The symptoms include emotional disturbance, uncontrollable movements, and intellectual difficulties. There are many factors that cause neurodegeneration; mitochondrial membrane potential and intracellular calcium levels are two main contributors. Membrane potential deals with a coding and transmitting signals between neurons, and calcium acts as a second messenger by assisting with the neurotransmitter release. When neurotransmitters receive excessive stimulation or high levels of calcium are detected, apoptosis or cell death occurs.

Recessive and dominant inheritance has a lot more affect than I thought. Working on this case study opened my mind to what dominant and recessive inheritance can lead to. In some cases it’s just whether or not you inherit a specific trait, in other cases, it deciphers whether or not you inherit an autosomal disorder. These disorders can cause huge impacts on the patients’s lives, like in my case study. I always thought about dominance and recessive inheritance as uppercase and lowercase letters, now I look at inheritance more closely.

Incomplete dominance

In addition to dominant and recessive inheritance, there is also incomplete dominance and co-dominance.  Incomplete dominance is where one trait is not entirely expressed. The outcome is generally a blend of traits where one does not dominates the other. Co-dominance is where both traits are expressed. In this circumstance, the outcome is a mix of traits and not a blend. These four methods of inheritance are all influenced by factors such as gender. Sex-linked, sex-influenced, and sex-limited traits all inherited differently. Sex-linked means that the gene is either carried on the x or y chromosome. Sex-influenced means that the intensity of the expressed gene differentiates between genders. Sex-limited means that the gene is only expressed by one gender. All three of these factors affects who can inherit the trait; only male, only female, or both.

Example of co-dominance

When looking deeper into inheritance of traits, you see that there is a lot more involved. There are multiple contributors determining inheritance, and they could be the deciding factor of if you inherit a genetic disease or not. It is incredible how much is actually involved in determining your DNA. From this research, I now see that inheritance is not just one gene from mom and one from dad. Understanding the types of inheritance and the basis of DNA pushes us towards the future of genetics and its infinite possibilities.

What are the different ways in which a genetic condition can be inherited? (2015, May 11). Retrieved May 14, 2015, from

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