Y chromosome microdeletion (YCM) is a family of genetic disorders caused by missing gene(s) in the Y chromosome. Many men with YCM exhibit no symptoms and lead normal lives. However, YCM is also known to be present in a significant number of men with reduced fertility. Men with reduced sperm production (in up to 20% of men with reduced sperm count, some form of YCM has been detected) varies from oligozoospermia, significant lack of sperm, or azoospermia, complete lack of sperm.
The mechanism of mutation is not different for Y-chromosome microdeletion. However, the ability to repair it differs from other chromosomes. The human Y chromosome is passed directly from father to son, and is not protected against accumulating copying errors, whereas other chromosomes are error corrected by recombining genetic information from mother and father. This may leave natural selection as the primary repair mechanism for the Y chromosome.
Y chromosome microdeletion is currently diagnosed by extracting DNA from leukocytes in a man's blood sample, mixing it with some of the about 300 known genetic markers for sequence-tagged sites (STS) on the Y chromosome, and then using polymerase chain reaction amplification and gel electrophoresis in order to test whether the DNA sequence corresponding to the selected markers is present in the DNA.
Quelle que soit l'envie
Quelle que soit la vie
Para?tre autre chose comme jouer un r?le
Demande beaucoup plus qu'il n'y parait
J'en suis l'exemple m?me
Comme une deuxi?me peau brod?e par l'habitude
Faite sur mesure pour cacher ce que je suis
Je ne suis rien du tout...
Mon id?al
Haut, toujours plus haut
Tu crois que para?tre ou savoir ?tre
Fait de toi quelqu'un d'autre
Mais le charisme se fait - je sais - avant l'attitude...