Why complete mole can have 46XX & 46xY karyotype but not 46YY and,
Why partial mole can have 69xxy,69xxx, and 69xyy karyotypes but not 69yyy . Why only YY, or YYY combination not possible. Can anybody explain this. Thanks.
Because you need at least 1 X chromosome for the cell to be functional. In theory, you could have two sperms with Y fuse to give you YY, but the cell they form will not survive. and YYY is just not possible because for a partial mole, you need an egg with a nucleus, and by definition an egg will always have a X chromosome so the only combinations possible are XYY or XXY or XXX, but not YYY