(GMN) Genetic Disorders and Karyotypes Introduction Lesson

It's In Your Genes

A newly married couple is interested in having children. She is concerned, however, because there is a history of Tay-Sachs in her family. Her husband is not concerned because neither one of them have this disease. What should they do? A genetic counselor can help determine if they are at risk for passing along Tay-Sachs to their offspring. They will analyze each of their pedigrees and help them determine the probability of their offspring having this condition. In this module, you will learn more about a variety of genetic disorders and how performing a karyotype can help diagnose some genetic conditions.

Genetic Disorders

Genetic disorders are diseases whose root cause is a mutation in the genome. The cause of genetic disorders may be from:

• a single point mutation (monogenic inheritance disorder)
• multiple genes with point mutations (multifactorial inheritance disorder)
• a combination of both inherited and environmental mutations
• chromosomal mutations (chromosomal disorder)

We will focus on some of the more well-known monogenic and chromosomal disorders in this lesson. You are responsible for knowing the basic information that would characterize each disorder as well as what type of genetic error causes it.

The Number 46

Each species has a characteristic number of chromosomes in the nucleus of all of its cells. The number of chromosomes has nothing to do with the complexity of the organism. For instance, a chicken has 78 chromosomes, a black mulberry plant has 308, and the human chromosome number is 46. Many disorders can be determined from performing a karyotype, which is a picture of chromosomes from an organism’s cell. It is arranged by homologous pairs. It is used to determine the sex of the offspring and some genetic disorders.

Take a Look at the Karyotypes Below

Normal Karyotype	Trisomy 21 Karyotype

This particular karyotype shows a condition called trisomy 21, meaning that there are 3 of the 21st chromosome. An individual with trisomy 21 displays Down Syndrome.

Genetic Disorders Challenge and Before You Go

Practice Time! Use the knowledge you learned from the lesson to complete the practice activities below.

  

Before You Go - You Need To Know

The following key points are from the explore section of the lesson. You must know the following information before moving to the next lesson. This is just a summary of the key points.

1. What is a genetic disorder?
   • A disease whose cause is due to a mutation in the genome.
2. What are the four categories of genetic disorders?
   • Dominant Allele Disorders
   • Recessive Allele Disorders
   • Sex-Linked Disorders
   • Chromosomal Disorders.
3. What is a karyotype?
   • A picture of the chromosomes in a cell. It is used to look for abnormalities in the genome.

IMAGES CREATED BY GAVS (FREEPIK)