Question Video: Suggesting Why a Person with a History of Inherited Diseases May Want Their Genome Mapped | Nagwa Question Video: Suggesting Why a Person with a History of Inherited Diseases May Want Their Genome Mapped | Nagwa

Question Video: Suggesting Why a Person with a History of Inherited Diseases May Want Their Genome Mapped Biology • Third Year of Secondary School

Cystic fibrosis is an inherited disease that affects the lungs and reproductive system of the sufferer. Why would somebody with a history of cystic fibrosis in the family want their genome mapped before they had a child?

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Video Transcript

Cystic fibrosis is an inherited disease that affects the lungs and reproductive system of the sufferer. Why would somebody with a history of cystic fibrosis in the family want their genome mapped before they had a child? (A) To determine how easy it would be for them to become pregnant. (B) To determine the sex of the child before it was born. (C) To determine if they were a carrier of the disease. (D) To determine the characteristics of the child.

This question presents us with an inherited disease called cystic fibrosis that affects the lungs, the digestive system, and the reproductive system of the sufferer. Let’s discuss how this disease is inherited and how genome mapping relates to this.

Cystic fibrosis results from a mutation in the cystic fibrosis transmembrane conductance regulator, or CFTR, gene. Cystic fibrosis is recessive, meaning two copies of the mutated gene are needed to produce cystic fibrosis.

You’ll recall that most of our cells contain two copies of each chromosome. The CFTR gene is located on chromosome seven. And in the situation represented here, this individual has two copies of the mutant CFTR gene, one from each of their two copies of chromosome seven. If someone only has one copy of the mutated CFTR gene, then they will not develop cystic fibrosis because they need two copies. Someone who carries a copy of the mutant allele without themselves showing the disease are called carriers.

When this individual who’s a carrier produces gametes, such as eggs or sperm, chromosome seven will be randomly allocated to these cells. So some gametes will have the mutant CFTR allele, while others will not. These gametes can then combine with another individual’s gametes who may also be a carrier. This would produce an embryo that carries two mutant copies of the CFTR gene. The resulting child would have cystic fibrosis.

One way to tell if an individual is a carrier or not for the mutant CFTR gene is to map their genome. That way, we would have a sequence of their two copies of the CFTR gene and could see if it was mutated or not.

Therefore, the reason someone with a history of cystic fibrosis would want to have their genome mapped before having children is given by answer choice (C): to determine if they were a carrier of the disease.

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