Question

Trisomy of chromosome 21 is called a. Down syndrome. b. Klinefelter syndrome. c. Turner syndrome. d. Jacobs syndrome.

Short answer

The correct answer is trisomy of chromosome 21 is called a. Down syndrome.

Step-by-step solution

Identifying Down syndrome

Down syndrome is a genetic condition caused by the presence of an extra copy of chromosome 21. Individuals with Down syndrome have three copies of this chromosome, leading to a total of 47 chromosomes instead of the usual 46. This condition usually leads to developmental delays, intellectual disabilities, and characteristic physical features.

Identifying Klinefelter syndrome

Klinefelter syndrome is a genetic condition that affects males. It results from the presence of an additional X chromosome, giving a karyotype of 47, XXY. This syndrome is characterized by small testes, lower testosterone levels, learning and language difficulties, and low fertility.

Identifying Turner syndrome

Turner syndrome is a genetic condition that affects females. In this condition, there is a complete or partial absence of one of the X chromosomes. The karyotype of affected individuals is 45, X or 45, X0. This syndrome is usually characterized by short stature, ovarian dysgenesis, heart defects, and learning and social difficulties.

Identifying Jacobs syndrome

Jacobs syndrome, also known as XYY syndrome, is a genetic condition that affects males. In this condition, there is an extra Y chromosome, leading to a karyotype of 47, XYY. This syndrome is characterized by tall stature, learning difficulties, and slightly increased risk of developmental disorders and behavioral issues.

Matching the correct syndrome with trisomy of chromosome 21

Based on the descriptions of each syndrome, we can see that Down syndrome is the condition caused by trisomy of chromosome 21. Therefore, the correct answer is: a. Down syndrome.