Genes are found on chromosomes in every cell in our bodies. The genes send information to the cell and make essential chemical products such as proteins. Thousands of genes provide information for the human body to develop, grow and remain healthy.
The human cell contains 46 chromosomes that are arranged into 23 pairs. One of every pair is passed to the offspring from each parent. 22 of the chromosome pairs are numbered, and the 23rd pair is made up of the sex chromosomes known as X and Y. Since chromosomes come in pairs, there are two copies of every one of the genes. The anomaly to this rule applies to the genes carried on the X and Y sex chromosomes. A change in a gene that produces a fault is what's known as a mutation. If a DNA change happens in only one of the pair genes, it leads to a health condition known as dominant mutation.
Dominant traits are those that need only one copy of the gene for them to express the disorder. X-linked characteristics mean that they are represented on the X chromosome. Remember that females possess two X chromosomes (XX), while males possess a single X chromosome (XY). Such a difference shows how they are affected by X-linked genes. In women, despite having two X chromosomes, only one is used for making the gene product, and the other X is switched off.
The switching off is known to occur randomly. This means that in some of the cells of a woman, one particular X chromosome will be switched off and in another cell, it will be active.
X-dominant inheritance happens when a gene that is responsible for the disorder or trait is found on the X-chromosome. The abnormal gene is usually from one parent that causes the disease. Both males and females can inherit the disorder or display the trait when they have a copy of the gene inherited from the parent.
A father usually passes the X-linked dominant gene mutation to all the daughters and all the Y chromosomes to all the sons. The unaffected mother gives the working gene to her children. There are two possibilities in the combination of the genes.
If the father carries the abnormal gene, all the daughters will inherit the disease. The main reason is that daughters always inherit the X chromosome from their father.
All his sons will be disease-free since sons only inherit the Y chromosome from the father. They will also inherit the working gene copy from their mother.
When a mother is affected by the condition, there are different combinations of genetic information that a child can get from their parents.
If the mother carries the abnormal X chromosome, half of all her children, both sons and daughters, will likely inherit the disease.
Mutations on the X chromosomes are usually recessive. This indicates that if there is a copy of the same gene working normally in each cell of an individual, they will not show symptoms of the condition. However, when a gene mutation is dominant, the body cannot work normally with less than the usual amount of working gene product. The X-linked dominant mutation will then override the unchanged information in the working copy of the gene. A woman having both of her X chromosomes contain a dominant gene mutation is exceptionally uncommon.
X-linked dominant disorders are generated by mutations in the genes on the X chromosome. A variation in one of the two copies is enough to cause the disease. In many of the cases, males usually experience more severe symptoms of the disorder than females.
Symptoms usually vary depending on the particular condition involved. Some conditions are linked to X-linked dominant inheritance. They include:
While there's no known treatment for the disorder, treatment depends on individual defects or anomalies presented.