What chromosome is affected in individuals with Down syndrome?

What chromosome is affected in individuals with Down syndrome?

• A. Chromosome 21
• B. Chromosome 18
• C. Chromosome 15
• D. Chromosome 22

Answer: (A)

Individuals with Down syndrome have an extra copy of chromosome 21, which is known as trisomy 21. This chromosomal abnormality occurs due to a nondisjunction event during cell division, leading to three copies of chromosome 21 instead of the normal two. The presence of this additional genetic material causes various physical and intellectual disabilities associated with Down syndrome, including distinct facial features, cognitive delays, and an increased risk of certain health conditions. The other chromosomes mentioned do not have any direct correlation with Down syndrome. For instance, abnormalities in chromosome 18 are associated with conditions like Edwards syndrome, while chromosome 15 anomalies are linked to Prader-Willi and Angelman syndromes. Chromosome 22 is linked to DiGeorge syndrome. Each of these conditions has distinct characteristics and symptoms that differ from those experienced by individuals with Down syndrome, emphasizing the specificity of the genetic abnormality related to chromosome 21.

Individuals with Down syndrome have an extra copy of chromosome 21, which is known as trisomy 21. This chromosomal abnormality occurs due to a nondisjunction event during cell division, leading to three copies of chromosome 21 instead of the normal two. The presence of this additional genetic material causes various physical and intellectual disabilities associated with Down syndrome, including distinct facial features, cognitive delays, and an increased risk of certain health conditions.

The other chromosomes mentioned do not have any direct correlation with Down syndrome. For instance, abnormalities in chromosome 18 are associated with conditions like Edwards syndrome, while chromosome 15 anomalies are linked to Prader-Willi and Angelman syndromes. Chromosome 22 is linked to DiGeorge syndrome. Each of these conditions has distinct characteristics and symptoms that differ from those experienced by individuals with Down syndrome, emphasizing the specificity of the genetic abnormality related to chromosome 21.