Sex - Basic Aspects of Human Sexuality

The Role of Chromosomes - Problematic Developments: Table 1

Chromosomal Problems

Modern research has found a number of possible atypical chromosomal conditions. The following desribes only the most important of them. As a rule, they concern deviations from the regular XX- or XY-combination. They are found in ca. 0,5 to 1 percent of the population.
 

In Girls

1. The so-called Turner Syndrome, i.e. only a single X-chromosome is present, the second one is missing (X0). The condition is characterized by stunted growth, a deficient development of ovaries, absent menstruation and absent breast development as well as infertility. Hormonal treatment can at least somewhat normalize the physical appearance. The syndrome is found in one of ca. 3000 live births.

2. The Triple X Syndrome (XXX), i.e. a third X-chromosome is present in addition to the two regular ones. The girl, and later the woman, will not differ from others in her appearance. However, she is likely to be less fertile, and she may also have psychological problems. The syndrome is found in one of ca. 1000 live births.
 

In Boys

1. The so-called Klinefelter Syndrome, i.e. the chromosomal combination XXY (or, very rarely, XXXY). It manifests itself in underdeveloped testicles, a low level of testosterone, a growth of breasts, disproportionate arms and legs, infertility and a likelihood of language disability. Hormonal treatments in adolescence can often achieve a masculinization of the body. The syndrome is found in one of ca. 1000 live births.

2. The XYY Syndrome manifests itself in malformations of the sex organs, reduced fertility, and other possible problems. The syndrome is found once in ca. 1000 live births.