Division of Pediatric Urology, Nicklaus Children's Hospital, Miami, FL, USA; Department of Urology, University of Miami Miller School of Medicine, Miami, FL, USA.
Department of Urology, University of Miami Miller School of Medicine, Miami, FL, USA.
J Pediatr Urol. 2021 Jun;17(3):346-352. doi: 10.1016/j.jpurol.2021.02.021. Epub 2021 Feb 24.
Klinefelter syndrome (KS) is an uncommon chromosomal disorder in males that has a variable clinical appearance. Classic KS involves an extra X chromosome, (47, XXY), although other variations may exist, including a milder mosaic form as well as multiple extra sex chromosomes with more dramatic phenotypes. KS is underdiagnosed, especially pre-pubertally, owing to a paucity of concrete clinical signs; however, diagnostic rates increase during and after puberty, as the consequences of hypergonadotropic hypogonadism begin to manifest. Testicular failure causing decreased circulating testosterone (T) and germ cell depletion, a hallmark feature in KS, commonly begins shortly after the onset of puberty and leads to the most commonly recognized KS traits: small testes, azoospermia, gynecomastia, decreased facial and pubic hair. While many KS men maintain adequate T levels leading up to young adulthood, some may have lower T levels at an earlier age leading to varied levels of androgenization and clinical KS features. At certain critical time points, absent or decreased T may alter the development of normal male reproductive organs, external genitalia, development of secondary sexual characteristics and spermatogenesis. Testicular failure in utero may lead to ambiguous genitalia, cryptorchidism and/or hypospadias, all of which depend on fetal T production. In the neonatal period and childhood, decreased T levels during the mini-puberty of infancy may negatively impact germ cell differentiation and male neuropsychological development. Finally, decreased T during pubertal and young adulthood can lead to decreased virilization during puberty, eunuchoid skeleton and decreased spermatogenesis. Depending on the timing of the testicular failure, a reproductive window of sperm production may exist to achieve paternity for KS men. The presence or absence of clinical characteristics reflecting decreased androgenization provides an insight to the relative testicular function during these developmental time points for those with KS and contributes to variability within the syndrome.
克氏综合征（KS）是一种男性罕见的染色体疾病，具有多种临床表现。经典的 KS 涉及额外的 X 染色体（47,XXY），尽管也可能存在其他变异，包括较温和的镶嵌形式以及具有更明显表型的多个额外性染色体。由于缺乏具体的临床体征，KS 诊断不足，尤其是在青春期前；然而，随着青春期和青春期后的后果开始显现，促性腺激素低下性性腺功能减退症的诊断率会增加。睾丸衰竭导致循环睾酮（T）减少和生殖细胞耗竭，这是 KS 的一个标志性特征，通常在青春期开始后不久就会出现，并导致最常见的 KS 特征：小睾丸、无精子症、男性乳房发育、面部和阴毛减少。虽然许多 KS 男性在成年前保持足够的 T 水平，但有些男性可能在更早的年龄出现较低的 T 水平，导致不同程度的雄激素化和临床 KS 特征。在某些关键时间点，缺乏或减少的 T 可能会改变正常男性生殖器官、外生殖器、第二性征和精子发生的发育。宫内睾丸衰竭可能导致生殖器性别模糊、隐睾和/或尿道下裂，所有这些都取决于胎儿 T 的产生。在新生儿期和儿童期，婴儿期迷你青春期 T 水平下降可能会对生殖细胞分化和男性神经心理发育产生负面影响。最后，青春期和成年早期的 T 水平下降会导致青春期时男性化减少、太监样骨骼和精子生成减少。根据睾丸衰竭的时间，KS 男性可能存在生育窗口，以实现生育能力。在这些发育时间点，缺乏或减少雄激素化的临床特征反映了相对睾丸功能，这为那些患有 KS 的人提供了一个了解相对睾丸功能的机会，并导致该综合征内的变异性。
