Difference Between Klinefelter and Turner Syndrome

Klinefelter syndrome is defined as the male hypogonadism that occurs when there are two or more X chromosomes and two or more Y chromosomes. Turner syndrome is the complete or partial monosomy of the X chromosome, which is characterized primarily by the hypogonadism in phenotypic females. Since there is usually one additional chromosome in Klinefelter syndrome, it is considered as a trisomy while tuner syndrome is regarded as a monosomy because one chromosome is missing in the affected individuals. This is the key difference between Klinefelter and Turner Syndrome.

CONTENTS

1. Overview and Key Difference
2. What is Klinefelter Syndrome
3. What is Turner Syndrome
4. Similarities Between Klinefelter and Turner Syndrome
5. Side by Side Comparison – Klinefelter vs Turner Syndrome in Tabular Form
6. Summary

What is Klinefelter Syndrome?

Klinefelter syndrome is defined as the male hypogonadism that occurs when there are two or more X chromosomes and two or more Y chromosomes. This condition is typically diagnosed after puberty because the testicular abnormality does not develop before the early puberty.

Clinical Features of Klinefelter Syndrome

1. Small atrophic testes and a small penis
2. Hypogonadism – Plasma gonadotropin concentration (especially FSH concentration) is elevated. Testosterone level is largely reduced, but the mean estradiol level is higher than the normal level
3. Abnormally elongated legs
4. Lack of secondary male sexual characteristics
5. Gynaecomastia
6. No mental retardation but the IQ is slightly less than that of the normal population
7. Increased incidence of type II diabetes and metabolic syndrome
8. Increased incidence of osteoporosis and bone fractures
9. Reduced spermatogenesis and male infertility

Patients having the Klinefelter syndrome have an increased risk of developing breast cancers, extragonadal germ cell tumors and autoimmune diseases such as SLE.

As previously mentioned, in a majority of the cases the Klinefelter syndrome is associated with the 47, XXY karyotype. This is due to the non-disjunction during the meiotic division of germ cells of one of the parents.

What is Turner Syndrome?

Turner syndrome is the complete or partial monosomy of the X chromosome which is characterized primarily by the hypogonadism in phenotypic females. The karyotype usually associated with the Turner syndrome is 45, X. This is because of the absence of an entire X chromosome, structural damages to the X chromosomes or the presence of mosaics.

Clinical Features of Turner Syndrome

1. Most severely affected individuals suffer from edema of the dorsum of hand and foot during infancy
2. Swelling of the nape of the neck can also be seen occasionally in the affected infants
3. Bilateral neck webbing
4. Short stature
5. Broad chest and widely spaced nipples
6. Coarctation of the aorta
7. Streak ovaries, infertility, and amenorrhea
8. Pigmented nevi

   Figure 02: 45, X Karyotype

What are the Similarities Between Klinefelter and Turner Syndrome?

• Both these conditions are cytogenic disorders involving the sex chromosomes.

What is the Difference Between Klinefelter and Turner Syndrome?

Summary – Klinefelter vs Turner Syndrome

The two genetic disorders discussed here are extremely common conditions. The main difference between Klinefelter and Turner Syndrome is that Klinefelter syndrome is a trisomy whereas Turner syndrome is a monosomy. The early diagnosis of them can be helpful in treating the complications arising from the underlying disease.

Image Courtesy:

1. “Human chromosomesXXY01” By User:Nami-ja – Own work (Public Domain) via Commons Wikimedia
2. “45,X” (CC BY-SA 3.0) via Commons Wikimedia

Reference:

1.Kumar, Vinay, Stanley Leonard Robbins, Ramzi S. Cotran, Abul K. Abbas, and Nelson Fausto. Robbins and Cotran pathologic basis of disease. Philadelphia, Pa: Elsevier Saunders, 2010. Print.