The klinefelter syndrome is a genetic abnormality of chromosomes occurs in males in which one extra X chromosome observed.

This clearly indicates that instead of one X and Y chromosome; two X and with a Y chromosome are observed in a karyotype of Klinefelter syndrome.

“75% of Klinefelter males never diagnosed.”

If you see someone taller than a normal male with some intellectual disability and infertility, he might be suffering from the present condition. Therefore, taller than the normal is a common sign of this condition.

Key talks: In the present article, we will explain to the karyotype of Klinefelter syndrome, some common symptoms and cause of it.

Related article: What does a human karyotype reveal?

What is Klinefelter syndrome is!

Let me tell you first that this chromosomal defect is only affects males. Also, the present chromosomal abnormality is one of the commonly observed world wide with 1 in 650 newborn boys.

As it is a kind of sex chromosome abnormality infertility is usually reported in majority of cases. In a cytogenetic language it is a disomy of chromosome X in which instead of a single X chromosome in male a pair of it is present.

However, in female the condition is totally different with three X chromsomes it becomes trisomy of X and known as super female.

As we said taller than normal and infertility are two major symptoms association with it. Besides some other sign and symptoms are:

• Small and firm testicles
• Small penis
• Gynecomastia- enlarged breast
• delayed puberty or sometime absent
• intellectual disability and developmental problems

In some cases with mild to moderate conditions, several symptoms are not observed at a younger age. Also, patients may suffer from hypotonia, motor skill, sitting, standing, and walking problems.

Klinefelter syndrome karyotype:

In Klinefelter syndrome instead of 46, a total of 47 chromosomes is observed. A patient has one extra X chromosome that occurs with X and Y. However, the present genetic condition is a bit tricky than others.

As a pair of X chromosome is present, the expression of genes located on X chromosomes doubles (due to an extra X). This causes developmental, intellectual and reproductive problems.

Besides, in 10% of cases, the mosaic Klinefelter condition is also noticed in which some cells carry an extra X chromosome while some are not. See the image below,

What does a Klinefelter karyotype show?

Total 47 chromosome are observed with one extra metacentric chromosome.

No deletion, duplication, translocation or inversion are reported. Chromosomal breakage and damage is also not reproted.

No any Y chromosomal abnormality observed.

No any autosomal abnormality reported.

Cytological indications: complete Klinefelter syndrome: 47, XXY (+X); for Mosaic Klinefelter syndrome: 46, XY/ 47, XXY.

Cause of Klinefelter syndrome:

Because of some unknown event is known as nondisjunction occurs at cell division the chromosome X becomes doubled. This means those genes which are located on X chromosomes becomes also duplicated. This even causes two increases in gene expression of X linked genes.

As the genes on the X chromosome are liked to mental, intellectual, and reproductive development, abnormalities in this system commonly appear. Infertility is one of the commonest symptoms of it.

Some other information…

• In some conditions two, three or four different X chromosomes are reported in Klinefelter syndrome. This is known as the variants of Klinefelter syndrome.
• Again none of the parents are responsible for it, the present genetic condition occurs totally random.
• The mortality rate because of the present condition is almost zero, although a person can’t make babies.
• Ambiguous genitalia if present can be removed surgically. A person can live a normal life.
• The process of creating Klinefelter karyotype is same as the Down syndrome. A conventional karyotyping set up is more than enough to encounter it.

Related article: Protocol for conventional karyotyping.

Conclusion:

FISH can be used to for screening of Klinefelter, however, the karyotyping is more common and cheap option. Care must be taken to avoid contamination.

Also huge expertise and experience is required to interpret the results.