Chapter 19, Problem 1QC

If you might be a carrier of a gene for an unpreventable condition, would you want to know? Why or why not?

Summary Introduction

To review:

The benefits of gene testing for knowing about the presence of a defected gene.

Introduction:

In genetics, a carrier is an individual, which has a recessive gene of a trait. These traits are not expressed in them as they are masked by the dominant allele of that particular trait. These recessive traits are inheritable, which can be transferred from one generation to another.

Explanation of Solution

It is necessary to know the genes that a person carries if those genes can cause an unpreventable condition. This is because these genes are inherited. This condition may not exist in the carrier, but there are chances that these traits express themselves in the next generation. This might happen when the carrier mates with a person actually having that disorder. It increases the chances of having an abnormal child.

Mostly, females are the carrier for a disease or disorder and the males express that particular disease when they also carry recessive alleles for that particular disease. This is because females have two pairs of homologous chromosomes, which means females have two X chromosomes. The disease will not be expressed in a female if the defected gene is present on one X chromosome. The second X chromosome masks the expression of the recessive allele.

When the affected gene is transferred to the male of the next generation, the disease will express itself. This is because males are hemizygous, that is they have X and Y chromosomes. The single X chromosome is acquired from the mother.

Thus, if a person knows about any defected genes present in them, they can avoid the transmission of this gene by marrying a person with dominant genes. In case the couple is already married, they can also decide to avoid conceiving any children or terminate the pregnancy. The couple can also get sufficient time to adapt emotionally if the pregnancy cannot be terminated.

Conclusion

Thus, it is necessary to know about the genes one carry if they can cause unpreventable conditions. This is because these genes will express in the next generation. Knowing about such genes gives a chance to plan for children and also in choosing suitable partners.