Klinefelter’s syndrome two X chromosomes in addition to a Y-chromosome ? present. The phenotype is male.
Klinefelter’s syndrome is the most common sex chromosome disorder. It occurs in about 1 in 500 male live births. The extra X chromosome originates in 60% of cases of the maternal side. The germ cells can not survive in the testes, leading to reduced sperm and androgens.
Klinefelter’s syndrome two X chromosomes in addition to a Y-chromosome ? present. The phenotype is male. Klinefelter’s syndrome is the most common sex chromosome disorder. It occurs in about 1 in 500 male live births. The extra X chromosome originates in 60% of cases of the maternal side. The germ cells can not survive in the testes, leading to reduced sperm and androgens. The boys involved are very large and have disproportionate arms and legs. They often have small, firm testes and about 30% develop gynecomastia. Puberty is a generally normal time. The beard is often weak. There is a predisposition to verbal learning disorders. The clinical picture varies greatly; but many 47, XXY males have a normal appearance and a normal intellect. Urinary excretion of FSH is often increased. The testes development ranges from hyalinized, nonfunctional tubules up to a certain production of spermatozoa. In about 15% of cases, a mosaic is available. The men involved are fertile. Some have next to a Y chromosome three, four and sometimes five X chromosomes. In general, the severity of mental retardation and abnormalities increases with the number of X chromosomes. Each additional X is associated a 15- 16-point reduction in IQ, where the language is most affected, particular attention to the expressive language skills. Diagnosis Prenatal diagnosis often when a cytogenetic examination is about due to the advanced age of the mother. Postnatal determined on the basis of the clinical features. Cytogenetic tests karyotyping, FISH analysis and / or chromosomal microarray analysis The diagnosis of Klinefelter’s syndrome is suspected with small testes and gynecomastia due to the physical examination of a youth. Many men are identified during the course of a Infertilitätsabklärung (probably all “nonmosaic” 47, XXY men sterile). The diagnosis is confirmed by cytogenetic analysis (karyotyping, fluorescent in situ hybridization [FISH] Analysis and / or chromosomal microarray analysis [CMA]). Therapy testosterone supplementation advice on fertility preservation immediately after the onset of puberty, men with Klinefelter’s syndrome should receive a lifetime Testosteronsupplementierung from puberty to ensure the development of male characteristics, muscle mass, bone, and better psychosocial conditions. Boys with Klinefelter’s syndrome usually benefit from speech and language therapy and neuropsychological tests for language comprehension, reading and cognitive deficits. After the onset of puberty boys should receive counseling regarding fertility preservation.