Are YY sex chromosomes common

Answer 1

The answer to this question relates to the karotype (the chromosomes) of an individual as opposed to the genotype (genes on the chromosomes) of an individual. Therefore a male cannot have a YY karotype.

In humans an X chromosome must be present to produce a viable child. Since the Y chromosome doesn't have sufficient genetic material to produce a viable child, neither would the presence of two Y chromosomes as both would lack the additional genetic material present on a X chromosome.
Viable offspring can have as few as one X chromosome with several instances of triploid individuals
including XXY, XXX and even XYY. Additional Y or X chromosomes occur due to errors during meiotic
division. An additional Y chromosome can only come from the male parent but additional X chromosomes can come from the male parent or the female parent.

Answer 2

No foetus will ever be viable without an X chromosome - so assuming you mean XYYY...

XYY syndrome occurs in about 1 in 1000 male births.

XYYY is very, very rare - but possible. This is usually associated with severe skeletal, intellectual and/or developmental difficulties (though this varies).

Answer 3

It is not possible to have a YY chromosome unless the chromosomes have been damaged. Women have XX chromosomes and men, who determine the sex of the child, have XY chromosomes, so the normal combinations are XY or XX. However, there are some genetic diseases that are caused by loss or damage to the sex chromosomes. Two of the diseases are XYY syndrome and XXYY syndrome,

Answer 4

They cross by having each parent donate ONE chromosome(there are exceptions but they're usually fatal or lead to some serious mutation). So basically in any combination you can only have one Y chromosome at most. XX and XY are the only normal combinations. XXY is possible but that's when an extra X chromosome is passed on. I think it's the mother who passes it down...It's been awhile since I've looked over genetics...I think for a more detailed answer, searching it yourself is better.

Answer 5

No, YY sex chromosomes are not common in humans. They typically do not exist in nature because the Y chromosome is necessary for male development, and having two Y chromosomes would result in non-viable embryos.