The genetic material contained within a human cell is inherited from the father to the offspring. Many of your features may resemble your parents – your hair color, your eye color, etc. The process by which you obtain these traits is called heredity.
Autosomal dominant disorders are genetic conditions that are passed down from generation to generation following a specific pattern.
Let’s analyze the inheritance pattern of the chromosomal disorders prevalent for you.
The human body contains two types of chromosomes – sex chromosomes and non-sex chromosomes or autosomes. In autosomal dominant disorders, the gene in question is located on the non-sex chromosomes.
Now, there are two genes. dominant and recessive. Recessive genes need two copies of the gene for the trait to be fully expressed. For example, if one parent has a recessive gene B for blue eye color and the other does not have a gene, the offspring will not have blue eyes. However, if both parents have the recessive B gene, there is a 25% chance that the child will have blue genes.
In dominant genes, one copy of it is sufficient to express the trait. Suppose one parent has the dominant gene B for blue eyes and the other does not; The offspring can still show blue eyes.
In chromosomal dominant disorders, the mutated gene or the carrier gene for the disorder is present on the dominant gene. A child of a person with any type of autosomal dominant disorder has a 50% chance of carrying the disorder.
Let us now discuss the types of dominant chromosomal disorders:
1. Huntington’s disease
by search Tamara Bringsheim and her teamThe prevalence of Huntington’s disease (HD) was 2.71 per 100,000 people. HD is a rare neurodegenerative disease that causes the breakdown of nerve cells located in the brain. It has a wide-ranging effect on a person’s cognitive and functional abilities. It also leads to:
- Movement disorders: involuntary jerking, unusual and slow eye movements, etc.,
- Cognitive malfunction, and
- Psychological disorders: depression, aggressive behavior, etc.
Neurofibromatosis is a group of autosomal dominant disorders that cause the development of tumors in the nervous tissue. Tumors can arise anywhere in the nervous system, including the brain, nerves, and spinal cord.
There are three different types of neurofibromatosis:
- Neurofibromatosis 1 (NF1): This type is usually diagnosed in childhood. Flat brown spots on the skin, small bumps on the iris, abnormalities in the bones, etc., are signs of the disorder.
- Neurofibromatosis 2 (NF2): The prevalence of NF2 is lower than that of NF1. The onset is generally characterized by benign, slow-growing tumors that significantly impair hearing.
- Schwannoma: This rare type of autosomal dominant disorder generally affects people after the age of 20. This causes tumors to appear in the cranial and spinal nerves and not around the ear or in the brain.
3. Muscular dystrophy
Muscular dystrophy (MD) is the most common form of a group of disorders called muscular dystrophies that begins in adulthood. It is characterized by muscle weakness and progressive muscle wasting. These people have prolonged muscle spasms. For example, a person with an MD may have trouble releasing the grip of a door handle.
Other common signs of the disorder include:
- Abnormalities in the electrical signals that control the heartbeat,
- clouding of the eye lens,
- Late development, etc.
Although it is impossible to prevent autosomal dominant disorders, several tests are available that may indicate potential risks. As you plan to start a family, talk to your health care provider and understand the risks of genetically related disorders that run in your family. A genetics counselor will be able to guide you through the testing process properly.
Did you know that not only physical illnesses but mental illnesses have been shown to have a genetic link to them? To learn more about the genetic inheritance of mental illness, click over here.
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