Autosomal Recessive Inheritance

Every human being is different from others. But it is quite strange that every human has a specific number of ears, eyes, nose, etc. But having the same number of organs, every human doesn’t resemble a similar one. There is a process that is responsible for this type of variation, this is known as mutation. Also, a child mostly has similarities with his parents. The skin color or eye color is mostly the same for every child. This similarity comes from the process known as Inheritance. Inheritance is the key element in nature. This helps to transfer the unique identification of the parents to their children. Unique identification is processed by the chromosomes. These are the carrier of the genes. The genes are unique for each identity.

Autosome Meaning

In the human body, there are 46 chromosomes are present. Among them, 44 are the non-sex chromosome & 2 are the sex chromosomes. The 22 pairs of chromosomes don’t play a role in determining the sex of the human body. They are responsible for the structure of the body. They provide some unique patterns to the body. On the other hand, the sex chromosomes are responsible for determining the sex of a human. There are two types of sex chromosomes. One is the X chromosome & another is the Y chromosome.

The chromosomes that are not responsible for determining the sex of the body are known as the Autosomal Chromosome or the Non-Sex Chromosome. 

These chromosomes are responsible for providing a particular identification to an individual. It helps to determine skin color, hair pattern, eye color, etc. There are specific genes for making each of the identities. Each gene has a different value in the human body. These chromosomes get these types of features from the parents of the offspring. Depending upon the genes, determine the identity of the offspring.

Dominant & Recessive Gene

There are mainly two types of a gene. This division can be done in each of the chromosomes. These types of divisions are needed to get the proper identification of an individual. Genes are an important component to determine identity. The chromosome only helps to inherit the genes from one generation to another. It completely depends upon the combination of the genes to show the identity of a particular individual.

A dominant gene means, if the gene is present on any chromosomal body, then the particular identity will be shown up. The presence of the dominant gene on any chromosome means that the identity will get visualized in the offspring. The dominant gene is written in the capital letter. If a gene is responsible for making blue colored iris of the eye. Then the dominant gene will be written as the ‘B’. The ‘B’ will indicate the dominant gene for the blue-colored iris feature.

The recessive gene is another type of gene. This type of gene can be found in every chromosome. But there is a difference from the dominant gene. The presence of the recessive gene on any chromosome will not show up in the identity of any individual. If the recessive gene is present with the dominant gene, then the feature of the dominant gene will be shown up. If the pair of recessive genes are present in any chromosome, then only the recessive identity will be visualized in individuals. The recessive gene is written in a small letter. If a gene is responsible for making recessive brown-colored iris of the eye. Then the recessive gene will be written as the ‘b’. The ‘b’ will indicate the recessive gene for the recessive brown-colored iris feature.

Characteristics of Autosomal Recessive Inheritance

1. Autosomal Recessive Inheritance can only be demonstrated by any carrier or affected individuals in between the parents. Without the carrier or affected person, the chance of getting autosomal recessive inheritance is nil.
2. It depends upon the chromosomal factors. Also, it depends upon the presence of the gene on the chromosome.
3. The recessive gene should be present on a certain chromosome. Without its presence, autosomal recessive inheritance will not work.
4. It was only able to work when there is a pair of recessive genes. Recessive genes along with the dominant genes will not able to show up the features of the recessive genes.
5. It is not only responsible for some special diseases among humans. But it is also responsible for developing our body structure. Our body components are made up of the proper presence of recessive genes.

Autosomal Recessive Inheritance

Autosomal Recessive Inheritance means the inheritance that is coming from the parents to the children with the help of autosomal recessive genes. In the autosomes, there are 22 pairs of chromosomes. On each chromosome, there are two pairs of genes. These genes are responsible for making the character of the individual. Now, the pattern of the genes should be considered. The pattern of genes will make the identity of the individual.

Two parents have a particular pattern of genes on their chromosomes. These genes are identifying a particular feature of the body. Both parents have the same pattern of genes. Having the dominant gene along with the recessive gene will only bring out the feature of the dominant gene. So, the parents are showing the identity of the dominant gene in their bodies. Now, after mating between these parents, there is a probability of having four offspring with different combinations of the genes.

There may be an offspring who only has the dominant gene in its chromosome. There may be two offspring who can have a dominant gene along with the recessive gene. Same as the combination of the parents. Also, there may be a chance of having one offspring who has two recessive genes on its chromosome. Having offspring of such a combination is known as autosomal recessive inheritance. As the offspring who has two recessive genes will show up the characteristics of the recessive gene on the body. As it will get the autosomal recessive characters from the parents. So, it is called Autosomal Recessive Inheritance.

The offspring that has two dominant genes are known as the Normal offspring. The offspring that has the dominant gene along with the recessive gene is known as the Carrier offspring. As they have the recessive gene on their chromosome. But the gene can’t able to show up its character due to the presence of the dominant gene. The offspring who have two recessive genes in their chromosome is known as the Affected offspring. Sometimes the recessive genes can carry the genes of some special diseases. So, after mating between two carrier parents, there is a 25% chance of having a Normal offspring, a 50% chance of Carrier offspring & 25% chance of an Affected offspring.

Pedigree Pattern of Autosomal Recessive

Pedigree is a special tree-like structure. This can be implemented with the help of the gene chart mentioned above. Here, in this case, the structure of a family is going to be implemented in the tree-like structure. Sometimes two or more families can combinedly define the pedigree of autosomal recessive. This type of representation helps to understand the inheritance process better.

• Traits often skip a generation.
• Equal no. of males and females are affected.
• If both parents are affected then all the progenies are affected.
• Most affected progenies have unaffected parents.

Autosomal Recessive Inheritance Diseases

Autosomal recessive inheritance sometimes causes different diseases in the human body. There is nearly a 25% chance of getting the combination of the recessive genes on the chromosomes. So, the chance is quite low. But nobody can define the combination of the offspring beforehand. Some diseases come from the combination of recessive genes with each other.

1. Sickle Cell Anemia: In this disease, the Red Blood Cells become stiffer & stickier. This causes a hamper of oxygen transportation. The RBCs in this disease lost their ability to transport oxygen to the vital organs. This causes more complications in the body. Nearly 1 in 12 African-Americans are a carrier of the gene of this disease.
2. Cystic Fibrosis (CF): This is also a disease related to autosomal recessive inheritance. In this disease, a thick mucus is developed. This mucous blocks the lungs & other vital organs inside the body. This causes severe damage to the body’s breathing. This can be found mainly in Caucasians.
3. Tay-Sachs Disease: This is another disease. This disease hampers the central nervous system of the body. There is a deficiency of a particular enzyme in this disease. This enzyme is known as Hex A. In this disease, a fatty substance developed in the nervous of the body. This will degrade the nervous system of the body. This process sometimes gets starts during pregnancy time. Nearly 1 in 30 of the European Ashkenazi Jewish Ancestry can have such a disease.

FAQs on Autosomal Recessive Inheritance

Question 1: What is the chance of having the combination of the recessive genes when a Normal father and Affected mother mate?

Answer:

If a normal father and an affected mother mate, there is no chance of getting the combination of recessive genes. In this case, 100% of offspring will be the Carrier type. This means they will all have the dominant genes along with the recessive genes.

Question 2: What is the chance of having the combination of the recessive genes when a Carrier father & Affected mother mate?

Answer:

If a carrier father & affected mother mate, there is a 50% chance of getting the combination of recessive genes. In this case, 50% of offspring will be the Carrier type. This means they will all have the dominant genes along with the recessive genes. And 50% will be the Affected type.

Question 3: What is the chance of having the combination of the recessive genes when an Affected father & Affected mother mate?

Answer:

If an Affected father & Affected mother mate, there is a 100% chance of getting the combination of recessive genes.

Question 4: Does the determination of gender perform by the autosomes?

Answer:

No, The Determination of gender performs only by the sex chromosomes. As autosomes will only be able to determine the feature of the body.

Question 5: Does the determination of hair color perform by autosomes?

Answer:

Yes! Autosomes are responsible for determining the features of the body. It helps to determine the color of the hair, the color of the eye, the color of the skin, etc. The autosomes show up these features.