Karyotype of a male patient shows the following, what is the clinical abnormality that is expected?
**Question:** Karyotype of a male patient shows the following: 46, XY, del(Y)(q11.2). What is the clinical abnormality that is expected?
**Core Concept:** Karyotype is a microscopic examination of chromosomes in cells, used to identify genetic abnormalities. In this case, we are considering a male patient with a deletion on the Y chromosome at q11.2.
**Why the Correct Answer is Right:** A deletion on chromosome Y at q11.2 is associated with a condition known as Klinefelter syndrome. This is a genetic disorder characterized by the presence of an extra X chromosome (47, XXY) in addition to the normal X and Y chromosomes. The clinical abnormality in this case is the manifestation of partial or complete absence of the Y chromosome.
**Why Each Wrong Option is Incorrect:**
A. 46, XY, del(Y)(q11.2) - This option contains the correct chromosomal abnormality, but it is not the answer because it only represents the genetic abnormality without mentioning the clinical manifestation.
B. 46, XY, +22 - This option represents a different genetic abnormality (duplication of chromosome 22) and is incorrect as it does not address the specific clinical abnormality associated with Klinefelter syndrome.
C. 46, XY, del(1)(q11.2) - This option represents a different chromosomal abnormality (deletion on chromosome 1) and is incorrect as it does not address the specific clinical abnormality associated with Klinefelter syndrome.
D. 46, XY, del(Y)(q11.2) - This option represents the correct chromosomal abnormality, but it is not the answer because it does not mention the clinical manifestation of Klinefelter syndrome.
**Clinical Pearl:** Klinefelter syndrome is characterized by a range of clinical features such as delayed puberty, small testes, gynecomastia (enlarged breast tissue), infertility, short stature, and delayed cognitive development. The most common feature is small testes, which leads to reduced sperm production and infertility in affected males.
**Correct Answer:** Klinefelter syndrome is characterized by the presence of a deletion on the long arm of the Y chromosome (46, XY, del(Y)(q11.2) which leads to the clinical manifestations associated with the syndrome, such as delayed puberty, small testes, gynecomastia, infertility, short stature, and delayed cognitive development.