Source: Human Male Karyotype image, Public Domain: http://upload.wikimedia.org/wikipedia/commons/5/53/NHGRI_human_male_karyotype.png; Down Syndrome Karyotype image, Public Domain: http://upload.wikimedia.org/wikipedia/commons/1/11/Down_Syndrome_Karyotype.png
A genetic disorder in which the 21st pair of chromosomes have three chromosomes vs. the normal pair, this is called a trisomy.
A condition in which a person has an XXY chromosomal pattern; males that inherit this are often infertile, may develop breasts and other female secondary characteristics and possible mental retardation.
When chromosomes don’t separate during meiosis causing gametes to have abnormal numbers, Down syndrome is an example of this.
A genetic condition in which an X chromosome is missing, if the child is not miscarried, the effects can range from non-life threatening to life threatening. People with Turner syndrome are female due to the presence of only an X chromosome, are almost universally infertile and typically have cardiovascular issues along with other organ system problems.
A condition in which a male inherits an extra Y chromosome; XYY syndrome doesn’t express any cognitive or life threatening abnormalities, it just tends to make males taller than average.