Video Transcript
Karyotypes are images of a person’s
chromosomes that can be used to determine chromosomal abnormalities. Which syndrome is likely to be
caused by the chromosomal abnormality shown in the karyotype provided? (A) Turner syndrome, (B) Down
syndrome, (C) Klinefelter syndrome.
This question is asking us to
identify the chromosomal abnormality that we see in this karyotype. First, let’s discuss this karyotype
in more detail.
Normally, we have a total of 46
chromosomes in the nucleus of our cells. This is actually 23 pairs of
chromosomes. These chromosomes are numbered one
to 22 based on their size. Chromosome one is the largest, and
chromosome 22 is the smallest. We have 23 pairs of chromosomes,
with one set coming from our biological father and the other coming from our
biological mother.
Besides chromosomes numbered one to
22, we also have the sex chromosomes. These determine our biological
sex. Having two copies of chromosome X
results in a biological female. While having a single copy of X and
a single copy of Y results in a biological male. Normally, we only have two sex
chromosomes. But in this karyotype, we can see a
total of three. Since these individuals possess a Y
chromosome, they will develop male characteristics. However, they will often be taller
than normal, with reduced facial hair, the development of breasts, and difficulty
conceiving children.
Having two copies of the X
chromosome and a single copy of the Y chromosome results in Klinefelter
syndrome. This occurs in one out of every 500
to 1000 newborn males. Therefore, the chromosomal
abnormality that is shown in this karyotype is given by answer choice (C),
Klinefelter syndrome.
