Things You Need To Know About Klinefelter's Syndrome (47 XXY Males)

An overview of Klinefelter's syndrome.

1. What is Klinefelter's Syndrome?

Via ghr.nlm.nih.gov

Klinefelter's syndrome (aka 47 XXY or XXY) is a disease caused by sex chromosome abnormality that results in a male individual containing two or more X chromosomes. It is one of the most common chromosomal disorders and occurs in 1:500 to 1: 700 male births worldwide. It was first identified by American endocrinologist Harry Klinefelter thus was named after him in the 1940s.

(source:

Klineferter, H., Reifenstein, E., & Albright, F. (1942) Syndrome characterized by gynecomastia, aspermatogenesis without a-leydigism, and increased excretion of follicle-stimulating hormone. clinical endocrinology, 2(11), 615-627.)

https://www.mayoclinic.org/diseases-conditions/klinefelter-syndrome/symptoms-causes/syc-20353949 )

2. Various forms of Klinefelter's syndrome.

Via testocreams.com

There are several variants of Klinefelter’s syndrome depending on the mutant chromosomal makeup. The most common form is 47 XXY. In other cases, there are 48 XXXY or 48XXYY form which occurs in 1:18,000 to 1:50,000, and 49 XXXXY form which occurs in 85,000 to 100,000, and very rarely 47 XYY or 47XXX forms. In this listicle, we will focus on the most common 47, XXY form.

(Source: http://www.klinefeltersyndrome.org/Variant_and_Prenatal.html)

3. How does it occur?

Via upload.wikimedia.org

What biological process is involved and goes wrong that leads to the extra copy of X chromosome in Klinefelter’s? It is believed that Klinefelter’s syndrome is not inherited but occurs at random. It is the result of nondisjunction during meiosis. Meiosis is the special cell division in the germ cells where the germ cell replicate its DNA once and divide twice to result in gametes that contains half the number of chromosomes. During meiotic division 1 or 2, sister chromatids or homologous chromosomes will evenly distribute into two daughter cells. If there is a mistake occurring at the X chromosome that causes nondisjunction of the sister chromatids or homologous chromosomes, then one of the daughter cells will contain an extra copy of the X chromosome. Then after fertilization, the zygote will have 47 chromosomes with 1 (or more) extra X chromosome.

(Source:

Bojesen, A., Juul, S., & Gravholt, C. (2003) Prenatal and postnatal revalence of Klinefelter syndrome: a national registry study. Clinical Endocrinology and Metabolism, 88(2) 622-626.)

4. What are the symptoms of Klinefelter's syndrome?

Most of the symptoms of Klinefelter’s are related to reproductive function. The extra copy of X chromosome results in lower testosterone production, which plays a critical role in male reproduction. As children, there is not a lot of signs but once the patient reach puberty and adulthood, the low testosterone level will result in smaller testes, and lower sperm count, and often leads to infertility. Androgens are key to maintain male characteristics, thus Klinefelter’s patients are often more feminine, with enlarged breasts.

(Source: https://www.nichd.nih.gov/health/topics/klinefelter/conditioninfo/Pages/symptoms.aspx

https://ghr.nlm.nih.gov/condition/klinefelter-syndrome )

5. Language and Learning Difficulties

Via patienttalk.org

Besides reproductive dysfunctions, there are many other symptoms associated with Klinefelter’s, such as cognitive and learning difficulties. Studies have shown that Klinefelter’s patient often experience a delay in learning to talk, troubles in using language to express thoughts and needs, troubles processing what they hear and reading difficulties. They also show social and behavior symptoms.

(Source:

Visootsak, J., & Graham, J.M. Jr. (2009). Social function in multiple X and Y chromosome disorders: XXY, XYY, XXYY, and XXXY. Developmental Disabilities Research Reviews, 15(4), 328-332.)

6. Cardiovascular and metabolic problems

Via upload.wikimedia.org

Other health risks associated with Klinefelter’s syndrome are cardiovascular and metabolic diseases. A study showed that Klinefelter’s patients have increased chances of developing cardiovascular diseases such as left ventricular diastolic dysfunction, reduced maximal oxygen consumption and impaired cardiopulmonary performance. In another study, researchers found that Klinefelter’s boys showed higher incidence of truncal obesity, insulin resistance and metabolic syndromes.

(Source:

Pasquiali, A. et al (2013) Cardiovascular abnormalitites in Klinefelter syndrome. International Journal of Cardiology, 168, 754-759.

Bardsley, M., Falkner, B., & Ross, J. (2011) Insulin resistance and metabolic syndrome in prepubertal boys with Klinefelter syndrome. Acta Paediatr, 100(6), 866-870.)

7. Is there a cure?

Via testosteroids.com

Since this is a chromosomal disease, it is impossible to correct the chromosome in every cell and cure the disease. However, depending on the symptoms, different treatment options are available. For low testosterone, hormone supplement of androgens will help to improve muscle mass, deepen the voice, promote the growth of facial and body hair and help the reproductive organs to mature. For enlarged breasts, the only treatment would be surgically remove or reduce the breast tissue. For infertility, assisted reproductive technology such as intracytoplasmic sperm injection has shown some success in Klinefelter’s males.

(Source: https://www.nichd.nih.gov/health/topics/klinefelter/conditioninfo/Pages/treatments.aspx

https://en.wikipedia.org/wiki/Klinefelter_syndrome )