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  2. Klinefelter syndrome - Wikipedia

    en.wikipedia.org/wiki/Klinefelter_syndrome

    This XXY chromosome arrangement is one of the most common genetic variations from the XY karyotype, occurring in approximately one in 500 live male births. [4] [13] [36] In mammals with more than one X chromosome, the genes on all but one X chromosome are not expressed; this is known as X inactivation. This happens in XXY males, as well as ...

  3. XXYY syndrome - Wikipedia

    en.wikipedia.org/wiki/XXYY_syndrome

    48,XXYY syndrome is a condition related to the X and Y chromosomes (the sex chromosomes). People normally have 46 chromosomes in each cell.Two of the 46 chromosomes, known as X and Y, are called sex chromosomes because they help determine whether a person will develop male or female sex characteristics.

  4. XYY syndrome - Wikipedia

    en.wikipedia.org/wiki/XYY_syndrome

    XYY syndrome, also known as Jacobs syndrome, is an aneuploid genetic condition in which a male has an extra Y chromosome. [1] There are usually few symptoms. [2] These may include being taller than average and an increased risk of learning disabilities. [1] [2] The person is generally otherwise normal, including typical rates of fertility. [1]

  5. Down syndrome - Wikipedia

    en.wikipedia.org/wiki/Down_syndrome

    The extra chromosome content can arise through several different ways. The most common cause (about 92–95% of cases) is a complete extra copy of chromosome 21, resulting in trisomy 21. [ 92 ] [ 97 ] In 1–2.5% of cases, some of the cells in the body are normal and others have trisomy 21, known as mosaic Down syndrome.

  6. XXXY syndrome - Wikipedia

    en.wikipedia.org/wiki/XXXY_syndrome

    XXXY syndrome is a genetic condition characterized by a sex chromosome aneuploidy, where individuals have two extra X chromosomes. [3] People in most cases have two sex chromosomes: an X and a Y or two X chromosomes. The presence of one Y chromosome with a functioning SRY gene causes the expression of genes that determine maleness. Because of ...

  7. Disorders of sex development - Wikipedia

    en.wikipedia.org/wiki/Disorders_of_sex_development

    Klinefelter syndrome (47,XXY and XXY syndrome) – a condition that describes a male born with at least one extra X chromosome. Though the most common variation is 47,XXY, a man may also be 48,XXXY or 49,XXXXY.

  8. Cornelia de Lange syndrome - Wikipedia

    en.wikipedia.org/wiki/Cornelia_de_Lange_Syndrome

    A gene responsible for CdLS on chromosome 5 was discovered in 2004 jointly by researchers at the Children's Hospital of Philadelphia, USA [6] and researchers at Newcastle University, UK. [7] CDLS2 300590: SMC1A: 5% In 2006, a second gene, on the X chromosome, was found by Italian scientists. CDLS3 610759: SMC3: 1% A third gene discovery was ...

  9. Trisomy - Wikipedia

    en.wikipedia.org/wiki/Trisomy

    The number of chromosomes in the cell where trisomy occurs is represented as, for example, 2n+1 if one chromosome shows trisomy, 2n+1+1 if two show trisomy, etc. [2] "Full trisomy", also called "primary trisomy", [2] means that an entire extra chromosome has been copied. "Partial trisomy" means that there is an extra copy of part of a chromosome.