The holandric gene is Y-chromosome linked. The mammalian Y chromosome appears largely heterochromatic under the light microscope and it carries few genes. The H-Y antigen gene has been assigned to the proximal region of the long arm of Y and the testis-determining factor, formerly called TDF, now SRF, is proximal to the centromere in the same arm in humans. The long arm also contains the pseudoautosomal region (PAS); this DNA sequence Yp (SMCY) is homologous to a X-chromosomal tract, Xp (SCX), the region where X and Y crossing over can occur. The gene for surface antigen MIC2Y was assigned to the euchromatic region Ypter - q1 of the Y chromosome. The homolog was assigned to a X-chromosomal band between Xp22.3 and Xpter. The azoospermia factor (AZF) Sp3 or HGM9 maps at the site of H-Y and may be identical with it. Genes controlling body height and tooth length were suspected to be in the Y-chromosome. An arginosuccinate and an actin pseudogene were located to the human Y chromosome. A gene for hairy ears was suspected to be in the Y chromosome but its status is not resolved with certainty. No hereditary disease gene is linked to the Y chromosome, although in aneuploids (XYY, XO), it may cause defects. Y chromosome, sex determination, differential segment, H-Y antigen, SRF, pseudoautosomal, azoospermia, pseudogene, actin, heterochromatin, surface antigen, hairy ear, imprinting; Jobling MA, Tyler-Smith C 2000 Trends Genet 16:356.
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