The key difference between X linked dominant and X linked recessive is that X linked dominant is a genetic disorder caused due to a dominant mutant gene located on the X chromosome while X linked recessive is a genetic disorder caused due to one or two recessive mutant genes located on the X chromosomes.
X linked dominant and X linked recessive are two types of X linked genetic inheritance. The inheritance is due to the genes located on X chromosomes. The genetic disorders occur due to the mutant genes located in X chromosomes. Females have two X chromosomes, while males have only one X chromosome. In males, one copy of the mutant gene is enough to cause X linked dominant or X linked recessive disorders. But in females, one copy of the mutant gene is enough to cause the X linked dominant disorder while two copies of mutant genes are needed to cause the X linked recessive disorder. Females that carry one recessive mutant gene in one X chromosome are carriers.
CONTENTS
1. Overview and Key Difference
2. What is X Linked Dominant
3. What is X Linked Recessive
4. Similarities Between X Linked Dominant and X Linked Recessive
5. Side by Side Comparison – X Linked Dominant vs X Linked Recessive in Tabular Form
6. Summary
What is X Linked Dominant?
X linked dominant is a disorder caused by a mutation in genes on the X chromosome. Only one copy of the mutant gene is sufficient for the disease to occur in both males and females. Some X linked dominant disorders are lethal in males. Moreover, males show severe symptoms of the X linked dominant disorder than females. However, a father cannot pass X linked inheritance to a son since the son receives only Y chromosome from his father. Therefore, there is no male-to-male transmission of X linked disorders. But affected fathers transmit this condition to their daughters.
Figure 01: X Linked Dominant
Some examples of X linked dominant condition include Vitamin D resistant rickets, Rett syndrome, Alport syndrome, Incontinentia pigmenti, Giuffrè–Tsukahara syndrome, Goltz syndrome, X-linked dominant porphyria, Fragile X syndrome and Aicardi Syndrome.
What is X Linked Recessive?
X linked recessive is a condition caused due to recessive mutant genes located in X chromosomes. In females, two mutant gene copies are needed for the disease occurrence. If one mutant copy is present, the normal copy can compensate for the changed copy. She is only a healthy carrier. But in males, one mutant copy is sufficient to cause the X linked recessive disease since males carry only one X chromosome. Males do not carry another copy to compensate the mutant copy like in females.
Figure 02: X Linked Recessive
Similar to X linked dominant disorders, fathers do not pass X linked recessive disorders to their sons. Some examples of X linked recessive conditions include haemophilia, Duchenne muscular dystrophy, Red-green colour blindness, X-linked ichthyosis and Becker’s muscular dystrophy.
What are the Similarities Between X Linked Dominant and X Linked Recessive?
- X linked dominant and X linked recessive disorders occur due to the mutations in genes on the X chromosome.
- One copy of the altered gene is enough to cause these two types of disorders in males.
- X linked disorders are not transmitted from father to son.
What is the Difference Between X Linked Dominant and X Linked Recessive?
X linked dominant is a genetic condition caused due to a dominant mutant gene on the X chromosomes. In contrast, X linked recessive is a genetic condition caused due to one or two mutant recessive genes on the X chromosomes. So, this is the key difference between X linked dominant and X linked recessive. Also, X linked dominant disorders are less common than X linked recessive disorders.
Moreover, in X linked dominant, only one copy is sufficient to cause the disease in both males and females. In X linked recessive, one copy is sufficient to cause the disease in males, but both copies are needed to cause the disease in females. Hence, this is another significant difference between X linked dominant and X linked recessive.
Below infographic tabulates the differences between X linked dominant and X linked recessive for side by side comparison.
Summary – X Linked Dominant vs X Linked Recessive
Genes located on the X chromosomes are responsible for X linked inheritance of diseases. X linked dominant and X linked recessive are two conditions. In X linked dominant, a dominant gene copy on the X chromosome causes the disease. In X linked recessive, one or two copies of recessive genes on the X chromosomes cause diseases. X linked recessive disorders are more common than X linked dominant. Moreover, X linked recessive condition more frequently affects males, while X linked dominant condition more frequently affects females. Thus, this summarizes the difference between X linked dominant and X linked recessive.
Reference:
1. “Inheritance Patterns.” Understanding Genetics: A New York, Mid-Atlantic Guide for Patients and Health Professionals., U.S. National Library of Medicine, 8 July 2009, Available here.
2. “What Are the Different Ways in Which a Genetic Condition Can Be Inherited?: MedlinePlus Genetics.” MedlinePlus, U.S. National Library of Medicine, 17 Sept. 2020, Available here.
Image Courtesy:
1. “X-linked dominant” By File:Autosomal dominant – en.svg: Domaina, Angelito7 and SUM1Derivative work: SUM1 – Based off of File:Autosomal dominant – en.svg (CC BY-SA 4.0) via Commons Wikimedia
2. “X-linked recessive (2)” By File:Autosomal recessive – en.svg: Domaina, Kashmiri and SUM1Derivative work: SUM1 – Based off of File:Autosomal recessive – en.svg (CC BY-SA 4.0) via Commons Wikimedia
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