The NICHD has a long history of supporting research to learn more about Klinefelter syndrome. Early research included a study that examined the cells of more than 40,000 infants for extra X chromosomes. NICHD-supported research has also explored topics including the roles of sex chromosomes in development; symptoms that arise in KS such as infertility, low testosterone, and problems with language, learning, and behavior; and how best to treat males with these symptoms. Among the areas of research that hold hope for more successful intervention and prevention in Klinefelter syndrome are studies in the following areas:
Genetics of Klinefelter syndrome. The full extent of the role of the X chromosome in development is not well understood. NICHD research into disorders of the X chromosome, such as Klinefelter, Turner, and Fragile X syndromes, will reveal more about how this chromosome functions and, ultimately, how to prevent or treat symptoms in individuals with an atypical number of X chromosomes. NICHD research also aims to improve understanding of processes that can go wrong in male germ cells before fertilization or right after it, when chromosomes conjugate and divide and can leave the resulting gamete with an unusual number of sex chromosomes.
Pathophysiological mechanisms of KS. KS alters hormonal balance, especially reducing testosterone levels, and exactly how this leads to infertility is unclear. Researchers are studying the mechanisms behind sperm creation and how Leydig cells function, which could identify interventions that may help preserve or restore fertility in males with KS. Investigations also include those on gonadotropin-regulated genes involved in the progression of testicular gametogenesis, Leydig cell function, and other endocrine processes.
Treatment strategies for KS. Research on early interventions has successfully limited the development and severity of symptoms in KS. The NICHD is gathering evidence to identify the best interventions for learning disabilities, osteoporosis (later in life), and infertility—all symptoms of KS.