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sex chromosome abnormalities (klinefelter's syndrome and variants [46,xy; 47,xxy; 47,xxy mosaicism]) |
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Klinefelter's syndrome is the most frequent sex chromosome abnormality. Pooled data from cystogenetic analysis of 9,766 newborn infants found Klinefelter's syndrome was present in 66(0.07%) of phenotypical males[2]. Adult men with Klinefelter's syndrome have small firm testicles that are devoid of germ cells. The phenotype can vary from a normally virilized man to one with stigmata of androgen deficiency, including female hair distribution, scanty body hair and long arms and legs because of late epiphyseal closure. |
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Leydig cell function is commonly impaired in men with Klinefelter's syndrome [4]. Testosterone levels may be normal or low, oestradiol levels normal or elevated and FSH levels are increased. Surprisingly, libido is often normal despite low testosterone levels, but androgen replacement may be needed with ageing. |
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Germ cell presence and sperm production are variable in men with Klinefelter's mosaicism 46,XY, 47,XXY. Pre-implantation fluorescent in-situ hybridization (FISH) analysis of cells from embryos can be used to confirm normality [5]. The production of 24,XY sperm has been reported in 0.9% and 2.1 % of men with Klinefelter's mosaicism [6,7] and in 1.36-25% of men with somatic karyotype 47,XXY [8-12]. This would indicate that some 47,XXY cells are able to achieve meiosis and produce mature spermatozoa. Conversely, it is not known whether haploid sperm in patients with Klinefelter's syndrome are always the result of a clone of normal cells in a mosaic population or whether, in certain circumstances, some 47,XXY male germ cells are viable and capable of producing haploid sperm. |
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Patients with Klinefelter's syndrome have an increased chance of producing 47,XXY spermatozoa. When IVF/ICSI is performed, pre-implantation diagnosis should be used or, if not available, amniocentesis and karyotype analysis. Embryos with known Klinefelter's karyotype should not be implanted. |
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Men with Klinefelter's syndrome are at risk for androgen deficiency as they get older and hormone replacement therapy may be needed. Long-term follow-up from an endocrine point of view will be needed for all men with Klinefelter's syndrome who have undergone testicular biopsy procedures for sperm retrieval. |
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