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We read and hear about inherited diseases all the time. We might even know a person that has a genetic disorder, but how are these illnesses passed from one generation to another? Here, we explain this and more about genetic disorders.

Of genes and DNA 

Genes are how our information is saved in every cell that is part of our body. This information is very important because it has the code that tells our cells how to function and the time at which they have to start performing those functions. For example, specific genes control the behaviour of bone cells, which proliferate during childhood and early adolescence, but stop doing it after a certain age. Without this genetic control program, bone cells would not know when to stop multiplying and we would continue growing for as long as our cells could.

When genes get damaged: Mutations

Changes in the genetic code would mean changes in the information that they keep and therefore, changes in the instructions that cells might receive. To avoid this, genetic information is well preserved in the DNA chain, which is at the same time restricted to the nucleus of each cell, protected by several mechanisms that avoid any changes that could be done to it.

Changes, also known as mutations, are unavoidable, though.

Even when the genes are very well protected, they do get damaged once in a while. This is a natural process that even helps in the evolution of species. However, when changes to the DNA content occur all of a sudden, they can severely affect the functions of a certain type or types of cells, giving as a result the development of medical conditions known as genetic diseases.

Genetic diseases and their cause

Not al genetic diseases are inherited, because mutations can be caused by external factors. For example, skin cancer is caused by DNA mutations after prolonged exposure to UV rays; another example is the exposure to toxic substances, which can also affect genes in white blood cells and cause certain forms of leukemia.

Inherited diseases, on the other hand, are the consequence of mutations that travel in our genes, from generation to generation.

How does this happen? When the egg and the sperm merge in the uterus of a woman, they combine their genetic information to give rise to a baby. Each one of them has 23 chromosomes, which are structures formed by coiled DNA, giving them an appearance of balls of wool. Every individual has a total of 46 chromosomes in each and every cell of his or her body, which come from the 23 chromosomes provided from mom and the 23 chromosomes provided from dad.

The information contained in chromosomes has the instructions that will start and continue the development of this human being, for the rest of his or her life.

And because half of our information comes from each of our parents, it is possible that we inherit our mom’s eye color or our dad’s face shape. Unfortunately, mutations that cause diseases are inherited too, and they can come from one or from both parents.

Diseases can be caused by an alteration in one or more genes.

Monogenic diseases are the easier ones to detect, since they occur as consequence of a mutation in a single gene. However, polygenic diseases are very difficult to study and to treat, because they can be caused by mutations in several genes, making it hard for researchers and doctors to determine their cause and to come up with effective treatments for them.

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