services - Klinefelter Syndrome

Klinefelter Syndrome

Klinefelter Syndrome is more common than many would think. It is identified in 0.1-0.2% of newborn boys. In the past, it was often diagnosed around the time of puberty or as an adult presenting with infertility. In fact, Klinefelter Syndrome is the most common genetic cause of male infertility. Approximately 3-4% of infertile men have Klinefelter syndrome.

What are the Features?

A lot of variability exists with respect to the features or manifestations of the Klinefelter’s. Some men may not have many or any of the classic features, while others may have several. Some of the features that have been described to occur in men with Klinefelter’s include: low testosterone levels, decreased body hair, increased height, gynecomastia i.e. breast tissue growth, widened hips, joint laxity, decreased muscle tone, delayed puberty, decreased testis volume, low testosterone, speech and comprehension difficulties, delayed balance and skill acquisition, enhanced visual memory and infertility.

The variability in features remains somewhat of a scientific conundrum; however, progress is being made. Many of the features of Klinefelter’s hinge on the balance and effect of sex hormones, i.e. testosterone and estradiol.  Variabilities exist in the sensitivity of the testosterone receptor among men. Furthermore, testosterone is normally converted to estradiol by an enzyme called aromatase. In men with Klinefelter’s, the aromatase activity is enhanced and increases the conversion from testosterone to estradiol more readily, although may vary between men with Klinefelter’s.

What is the likelihood of Fertility?

The majority of men with Klinefleter’s will not have sperm detectable in their semen. In many cases, the number of sperm present are not enough for naturally conceived pregnancies and assisted reproductive techniques may be necessary. Among men with no sperm detectable, surgical sperm retrieval will be necessary using the gold standard technique termed microTESE (see microTESE section). MicroTESE is successful in up to 70% of men with Klinefelter’s, and sperm identified may then be used for IVF-ICSI technique (in vitro fertilization – intracytoplasmic sperm injection).  The majority of sperm retrieved from men with Klinefelter’s have a normal karyotype, and only 1.5-6% of sperm will have an extra ‘X’ chromosome. Some controversy exists among experts related to the timing of surgical sperm retrieval. This is because some studies have shown better results for sperm retrieval among younger men with Klinefelter’s compared to older men; however, other studies have not identified this association. Thus, it is important to have a discussion with one’s fertility expert to determine the optimal timing of sperm retrieval in each individual scenario.

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