Genetic disorders are a topic in biology that can not be avoided. The fact is that genetic disorders can happen in humans, plants or animal. No one and nothing is safe from a genetic disorder. A genetic disorder can appear in the first years off life, or can appear much later in life when least expected.
A basic principal of biology states that the behavior of chromosomes during the meiosis process can account for genetic inheritance patterns. There are many reasons for genetic disorders. To start it is important to understand what a genetic disorder is. It is a mutation in the genetic material of a person. The mutant gene is transmitted thru birth. These genetic mutations can create serious complications and even death.
It is important to understand how people get certain traits and genes. A person receives one set of chromosomes and genes from each person. That means each person inherits the traits. One gene may be more influential then another in developing specific traits. The more powerful gene is called the dominant gene and the less powerful is the recessive. A variation of a gene and the trait it controls, such as the color of ones eyes or hair is called in allele.
Most diseases have genetic disorders. A diseases springs from genetics that are passed along from the parents. So called genetic diseases can be classified in 3 ways single gene defects, chromosomal disorders and multi factorial. 1 in 200 births have single gene defects. There are over 6000 different known single gene disorders. These kind of disorders are characterized by the way they are carried thru a family.
In dominant inheritance the child of a carrier has a fifty percent chance of inheriting the gene. The parents of the children with genetic disorders are definitely carriers. While in recessive inheritance the parents do not necessarily have the gene. The chances vary with each generation of recessive genes. It also depends on the sex of the baby. Recessive traits can only be expressed if both of the genes have the same mutation.
Without both parents having the gene it is impossible for the disease to show up in their child. Although the child can have the recessive trait. That is homozygous traits. Heterozygous traits are apparent even if only one gene in a pair has the mutation. Common recessive diseases are cystic fibrosis, sickle cell anemia, Tay Sachs.
Alzheimer and Huntington diseases are examples of dominant disorders. Some mutant disorders occur on the X chromosome. Females have little or no effects if the mutation occurs on the X linked gene. Males on the other hand do not have another X chromosomes so do not have another gene to fall on. Dominant disorders linked to the X chromosomes are usually very deadly to males. These disorders tend to affect men more then women.
Almost exclusively. Some of the diseases associated with the X are down syndrome, Hemophilia. There are also the diseases that occur on the sex genes. They also come in recessive and dominant forms. With this it determines who will get the disease. For example a mother can pass on a trait to a daughter but not to a son and vice versa.
One can not forget that genetic disorders can also occur because of external effects. Things like cigarette smoking and drinking during pregnancy can affect the babies genetics. Leaving the baby with one of the genetic disorders. Sickle cell anemia is a genetic disorder that usually appears between the ages of 2 and 4 years old.
The red blood cells are shaped like crescents or sickles. The red blood cells only last about 10 to 24 days. In a healthy person they last about 120 days. That is where the anemia part of the name comes into play. Studies have shown that the people most prone to the disease are of Mediterranean or African decent.
Although unhelpful in the United States in Africa it helped to combat against Malaria. Homozygous people have inherited the two copies of the gene making them prone for the disease. People who have inherited one copy of the gene are heterozygous. They are carriers of the trait but are not under immediate threat. However under certain circumstances their have been cases of people developing the disease from the recessive gene. In simple terms in order for a person to have the disease both parents must have the trait.
If only one parent has the disease there is a chance of the trait being passed on. Huntington disease is a degeneration of the nervous system. It usually occurs in the older part of someone life. As the disease becomes worse it could cause uncontrollable movements in the body.
Because the disease causes loss of brain cells, a person can lose memory. It can also contribute to depression. It takes about to ten to twenty years after the first signs of the disease for death to follow. Huntington is a dominant disorder.
Children of carriers have a fifty percent chance of inheriting the disease. It is not mandatory for both parents to have the trait for it to be passed on. Huntington is a single gene disorder. Meaning that even if only one parent has the trait the disease can still occur. Alzheimer is on the other hand not a single cell gene disorder. More then one gene mutation can cause this disease.
In some cases one gene from each parent is needed in order for the person to get the disease. All offspring in one generation have a fifty / fifty chance of getting this disease. Alzheimer is similar to Huntington in that one loses memory. It usually occurs between the ages of forty and fifty. It currently affects four point five million people. It is a very hard disease for many people.
It usually onsets in the later years of ones life. There are also non lethal genetic diseases. These diseases are caused by dominant alleles. And although they do not kill can be quite harmful to people because of their self esteem. Webbed feet or hands. Polydactyly is a disease that give a person an extra finger or toe.
It is a disease that is caused by dominant inheritance It is important to once again stress that in these disease on gene is more dominant then another. That is why the disease occurs. In this paper it has become evident that most alleles show complete penetrance. But their are some that do no.
For example the dominant allele that causes polydactyly Dominant and recessive genes are an important part of the genetic disorders in a person. It is possible for a person to go their whole lives without knowing that they have a disease. It is important for people to get testing done early to try and prevent some of these disease from occurring in them and their offspring. Although not all of these diseases can be cured some can be prevented and suppressed. Many people live long and productive lives with these diseases. The diseases that are listed in the paper are just but a little taste of the many diseases that can occur in a child or an adult.
Inheritance plays a big part of how genetic diseases occur in a person. As a rule there are sporadic times when abnormalities occur in the gametes. Therefore it is possible for only one person in a huge family to have a disorder. When diagnosed with certain disease it is very obvious. Yet it might take time for the afflicted person to have symptoms.
It is important for parents who are expecting children to try and map out their family history of diseases. That way they can see if either of them might have 1 dominant or recessive gene. It is possible for a family to go many generation without any of the genetic disorders showing up. Understanding the disorders and how they happen can help parents to prevent having children who will suffer for many years.
There is many different ways for a person to inherit a mutated gene.