Lesson 3.10

What are the 4 types of genetic tests?

Karyotyping, FISH, gene testing, and biochemical testing.

What does karyotyping analyze?

Chromosome number and structure

What does FISH testing analyze?

Specific regions on chromosomes using fluorescence.

What does gene testing analyze?

Mutations in the DNA sequence of a gene.

What does biochemical testing analyze?

Abnormal enzymes or proteins caused by gene mutations.

What is cystic fibrosis?

An inherited disorder that damages the lungs, digestive tract, and other organs.

What gene is linked to cystic fibrosis?

The CFTR gene.

What chromosome is the CFTR gene found on?

Chromosome 7.

What chromosome is the Huntington disease gene found on?

Chromosome 4.

What DNA sequence is repeated in Huntington disease?

The CAG nucleotide sequence.

What does the Huntington disease genetic test measure?

Number of CAG repeats

What do fewer than 35 CAG repeats mean?

The person will not be affected.

What do 36–39 CAG repeats mean?

The person is at risk of developing the disease.

What do more than 39 CAG repeats mean?

The person will definitely develop Huntington disease.

What is a genetic counsellor?

A health care professional trained in medical genetics and counselling.

What is a pedigree?

A flowchart that uses symbols to show inheritance patterns in a family over generations.

How do genetic counsellors use pedigrees?

They use pedigrees to determine genotypes and explain the chance of passing on a disease-causing allele.

What are some issues with genetic testing?

Stress, guilt, family decisions, discrimination, insurance problems, and deciding whether or not to know.

Why might someone choose genetic testing?

To plan for the future, make family decisions, or get early treatment/preventive care.

Why might someone not want genetic testing?

They may not want to know their risk, especially if there is no cure.

Does a positive genetic test always guarantee disease?

No. Some positive tests only show increased risk, not a guaranteed disease

What is gene therapy?

A technique that treats genetic disorders by introducing the correct form of a defective gene into a patient’s genome.

What is a vector in gene therapy?

A carrier used to deliver DNA into a cell.

Why are viruses often used as vectors?

Because viruses can easily infect human cells and deliver genetic material.

What is one obstacle of gene therapy?

Viruses can cause an immune response.

What is another obstacle of gene therapy?

The new gene may not integrate properly into the chromosomes.