X chromosome: A sex chromosome found in both females and males. Normal females usually have two X chromosomes. Normal males usually have one X along with a Y chromosome. The complete chromosome complement consisting of 46 chromosomes is conventionally written as 46,XX for females and 46,XY for males.
The X chromosome carries hundreds of genes. Only a minority of the genes on the X have anything to do with sex. This is consistent with the concept that the X and Y chromosomes evolved from an ancient pair of autosomal (nonsex) chromosomes and that the X chromosome retains much of its old autosomal information.
The inheritance of genes on the X follows special rules because males have only a single X chromosome, almost no gene on the X has a counterpart on the Y, and genes on the X are expressed in males. Genes inherited in this manner are said to be sex-linked or, more precisely, X-linked.
Examples of the genes on the X chromosome include those for the enzyme steroid sulfatase, episodic muscle weakness, ocular albinism, Charcot-Marie-Tooth disease (one kind of this neurologic disease), retinoschisis (retinal splitting due to degeneration), infantile spasm syndrome, agammaglobulinemia (a form of immune deficiency), Aicardi syndrome, Duchenne and Becker muscular dystrophy, chronic granulomatous disease, hemophilia A, hemophilia B, and red-green colorblindness.
The X chromosome is one of the two sex chromosomes in humans (the other is the Y chromosome). The sex chromosomes form one of the 23 pairs of human ...
Library > Literature & Language > Dictionary or X chromosome ( ĕks ' krō ' mə-sōm ' ) n. The sex chromosome associated with female characteristics in mammals ...
Sex Chromosomes. The nuclei of human cells contain 22 autosomes and 2 sex chromosomes. In females, the sex chromosomes are the 2 X chromosomes. Males have one X chromosome ...
chromosome /chro·mo·some/ (kro´mah-sōm) in animal cells, a structure in the nucleus containing a linear thread of DNA which transmits genetic information and is ...
X chromosome (genetics), ... Email" is the e-mail address you used when you registered. " Password" is case sensitive.