Sex chromosomes are susceptible to a number of aberrations. These are associated with a wide variety of problems, particularly in the areas of sexual development. So far, more than 70 irregularities of the sex chromosomes have been identified. The purpose of this paper is to discuss two of these abnormal genetic conditions: (1) Klinefelter's Syndrome; and (2) Turner's Syndrome. Each condition is discussed in terms of genetic structure, historical background, etiology and treatment considerations.
In 1942, Klinefelter, Reifenstein and Albright described nine men who shared an odd set of characteristics. These included, among other things, shrunken testes, breast development (gynecomastia), and elevated urinary gonadotropins. Eventually this combination of symptoms was termed "Klinefelter's syndrome" after the first author.
In the 1950s, researchers demonstrated that individuals with these symptoms possessed an extra X chromosome, resulting in a genetic combination of XXY; subsequent studies have indicated that Klinefelter's syndrome usually occurs whenever a person has more than one X chromosome in the presence of at least one Y chromosome (Drew, Logan & Hardman, 1984). While occasionally individuals are found with the combination XXXY, more than 75 percent of Klinefelter cases are XXY, and this syndrome occurs in about one out of every 1,000 live male births.
Drew, Logan and Hardman (1984) report that older maternal age seems to be the predisposing factor for the occurrence of the extra X chromosome found in the infant; in this regard, the average maternal age of women giving birth to boys with Klinefelter's syndrome is about 32 years (Levitan & Montagu, 1977). Despite the fact that the condition is present at birth, diagnosis is generally not made until puberty (Sue, Sue & Sue, 1994).
In addition to the symptoms first described by Klinefelter and his colleagues, the syndrome can also include low levels of testo...