What is a Genetic Disorder?
When we hear about the term genetics, a couple of important vocabulary words come to mind. We might remember DNA, the foundation of life, and the fundamentals of genetics. We also might consider proteins, and branch from there, but the main part of Genetic Disorders involve DNA (Image 1). Genetic Disorders are diseases caused by a change in the DNA sequence of nucleotides that make up you as a person. Genetic Disorders occur usually through Mutations, as the normal strand is altered into a new strand. Mutations are in different types including point mutations, chromosomal mutations deletions, insertions, and many more. Genetic Disorders can be neutral, positive, or negative and is random, which could lead to serious changes in your life. Before going deep into genetics, we need to know quite a bit about genetics, and about DNA and the specifics. Let's learn more about Genetic Disorders ("Genetic Disorders", 2021).
Image:1 Basic Genetic Vocabulary needed for this website.
Sex - Linked, Autosomal Dominant, Recessive
Before we go any further, we have to talk about the basics of genetics, dominant and recessive. This is known as Mendelian Inheritance, in which George Mendel found out this information while examining Pea plants. Individuals receive two versions of the genes called alleles from each parent. If the allele is expressed, that means that it is the dominant allele. When the dominant allele is expressed, the recessive allele is masked, and only comes out when both alleles for a person are recessive. Dominant always expressed more than recessive. An autosome means any chromosome that is not a sex chromosome. These are chromosome pairs 1-22 (Image 3). If you receive a disorder on this chromosome, it is autosomal. These chromosomes are not affected by the sex of the person, but sex-linked chromosomes depend on the sex. If the person is a male, they will have one x and one y chromosome but women have 2 X chromosomes(Image 2). The X Chromosome is bigger and has a higher chance of having a disorder on it, meaning that men are more prone to sex-linked genetic disorders. Since now we know the groupings of the disorder, now let's talk about the single vs polygenes ("Genetic Basis", 2018).
Polygenic Disorders vs Single Gene
A Polygenic Disorder is a Disorder where multiple genes are influenced. Instead of being caused by a single gene, multiple genes are coordinated to cause that certain disorder. These disorders involve multiple proteins because genes are made out of proteins. Whenever forming these genes, small errors can cause serious issues in the future. On the other hand, single-gene disorders (AKA Monogenic Disorders) only revolve around one single gene. Using prior Biology knowledge, we know that genes are required to code amino acids. Genes are on the DNA strand, and for each different trait, there is a different gene affecting it. If a certain genetic disorder has only one gene that contributes to it, it is a single gene disorder (Image 4). Now, since we have recapped basic genetics, we can start diving into Genetic Disorders and much more information about them("Single Gene", 2021).
Image 2: Talking about X-Chromosome linked recessive inheritance
Image 3: This is differentiating Autosomal Dominant and Recessive Inheritance
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Image 4: Differentiating Polygenic vs Single Gene Disorders
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Last edited: December 9, 2021