Although the letter X can be used as a symbol in various ways (such as with X-rays, the X-axis of a graph, etc.), “the X ” in genetics and medicine today usually refers to the X chromosome.
The X is the sex chromosome that is found twice in chromosomally normal females and singly along with a Y chromosome in chromosomally normal males. The complete chromosome complement consisting of 46 chromosomes including the two sex chromosomes is thus conventionally written as 46,XX for chromosomally normal females and 46,XY for chromosomally normal males.
- Y chromosome
The sex chromosome that is found, together with an X chromosome, in most normal males. The Y chromosome contains the unique male-determining gene and the male fitness genes that are active only in the testis and are responsible for the formation of sperm. Other genes on the Y chromosome have counterparts on the X chromosome, […]
- Y chromosome infertility
Male infertility with oligozoospermia (a subnormal number of sperm) or azoospermia (the absence of sperm) caused by deletion or rearrangement of the long arm of the Y chromosome, as demonstrated by chromosome analysis or by molecular studies which may show microdeletions (of region AZFa, AZFb, or AZFc) of the Y chromosome. Y chromosome infertility is […]
- Y chromosome sex-determining region
The region on the Y chromosome that decides the sex of the individual. Abbreviated SRY. SRY is necessary for male determination. It encodes the testis-determining factor. Mutations in SRY are responsible for XY females with gonadal dysgenesis who appear to be normal females at birth but at puberty do not develop secondary sexual characteristics (such […]
- Y map
The array of genes on the Y chromosome.
- Y sex-determining region
A region on the Y chromosome that determines the sex of the individual. This region goes by the symbol SRY (sex region Y). SRY is necessary and sufficient for male sex determination. It is the testis-determining factor. Mutations in SRY give rise to XY females with gonadal dysgenesis who appear to be normal females at […]