ArticleGENETIC ASPECTS OF KLINEFELTER'S SYNDROME
K. Kavitha * , *, Ramarao Nadendla, A. Narendra Babu, J. Naga Lakshmi, Shaik Munwar
K. Kavitha *
Klinefelter's syndrome (KS) is the most common chromosome aneuploidy in males, characterized by at least one supernumerary X chromosome. Although extensively studied, the pathophysiology, i.e. the link between the extra X and the phenotype, largely remains unexplained. The scope of this review is to summarize the progress made in recent years on the role of the supernumerary X chromosome with respect to its putative influence on the phenotype. In principal, the parental origin of the X chromosome, gene-dosage effects in conjunction with (possibly skewed) X chromosome inactivation, and especially concerning spermatogenesis meiotic failure may play pivotal roles. One of the X chromosomes is inactivated to achieve dosage-compensation in females and probably likewise in KS. Genes from the pseudoautosomal regions and an additional 15% of other genes, however, escape X inactivation and are candidates for putatively constituting the KS phenotype. Examples are the SHOX genes, identified as likely causing the tall stature regularly seen in KS. Lessons learned from comparisons with normal males and especially females as well as other sex chromosomal aneuploidies are presented. In addition, genetic topics concerning fertility and counseling are discussed. Klinefelter syndrome, affecting males, is a collection of characteristics that occurs as a result of two or more X chromosomes. The syndrome was named after Harry Klinefelter, an American endocrinologist, and is common - occurring in all races. It is thought that one male in every 500 live births is affected and the incidence is rising. However, this may be due to increasing awareness, reflective of the sophistication of the methods to diagnose. Most men with Klinefelter syndrome produce little or no sperm, but assisted reproductive procedures may make it possible for some men with Klinefelter syndrome to father children.
Klinefelter syndrome, SHOX genes, X chromosome, Testicular growth, Testosterone