Sickle-cell anaemia isa)X-linked recessive inheritanceb)Autosomal domi...
Autosomal recessive inheritance means that the gene is located on one of the autosomes (chromosome pairs 1 through 22). This means that males and females are equally affected. "Recessive" means that two copies of the gene are necessary to have the trait, one inherited from the mother, and one from the father.
Examples of autosomal recessive disorders include cystic fibrosis, sickle cell anemia, and Tay Sachs disease.
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Sickle-cell anaemia isa)X-linked recessive inheritanceb)Autosomal domi...
Sickle-cell anaemia is a genetic disorder that affects the red blood cells. It is caused by a mutation in the HBB gene, which provides instructions for making a protein called hemoglobin, responsible for carrying oxygen throughout the body. This mutation leads to the production of abnormal hemoglobin molecules, known as hemoglobin S, which can cause the red blood cells to become sickle-shaped.
Autosomal Recessive Inheritance:
Sickle-cell anaemia is inherited in an autosomal recessive manner. This means that both copies of the HBB gene must have the mutation for the disorder to be present. If only one copy of the gene is mutated, the individual is said to be a carrier of the trait but does not develop sickle-cell anaemia.
Key points:
- Autosomal recessive inheritance means that the gene responsible for a disorder is located on one of the autosomes (non-sex chromosomes).
- For an individual to have sickle-cell anaemia, they must inherit two copies of the mutated gene, one from each parent.
- Individuals who inherit only one copy of the mutated gene are carriers of the trait and usually do not show symptoms of the disorder.
- If both parents are carriers, there is a 25% chance with each pregnancy that their child will have sickle-cell anaemia, a 50% chance that the child will be a carrier, and a 25% chance that the child will neither have the disorder nor be a carrier.
Other inheritance patterns:
- X-linked recessive inheritance: This pattern of inheritance involves genes located on the X chromosome. Since sickle-cell anaemia is not linked to the X chromosome, it is not an X-linked recessive disorder.
- Autosomal dominant inheritance: In autosomal dominant inheritance, only one copy of the mutated gene is needed for the disorder to be present. However, sickle-cell anaemia requires two copies of the mutated gene, making it inconsistent with autosomal dominant inheritance.
- X-linked dominant inheritance: This pattern of inheritance involves genes located on the X chromosome. Since sickle-cell anaemia is not linked to the X chromosome, it is not an X-linked dominant disorder.
In conclusion, sickle-cell anaemia follows an autosomal recessive inheritance pattern, where both copies of the HBB gene must have the mutation for the disorder to be present.
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