Autosomal and Sexual Aneuploidy

Prepared by:Endino, Jommel M.

Martinez, Carla Fe C.

AAPD2B

What is Aneuploidy?

•Aneuploidy is the term used to describe a chromosome problem, that is caused by an extra or missing chromosome.

Sexual and Autosomal

Sexual Aneuploidy happens in the sex chromosomes.

Autosomal Aneuploidy happens in the autosomes.

Autosomal Aneuploidy

Down syndrometrisomy 21

It is a common autosomal trisomy among live –born children ,it has frequency of about 1 in 800 of live birth .

It doesn't usually run in families and it increases with the mother age.

psychological symptoms Children with this

syndrome are invariably mentally retarded.

There is similarity between people with Alzheimer disease and adults ”over 30” with down syndrome . They share memory loss, confusion, anxiety ,and lost of ability to perform simple tasks like dressing or feeding .

There are of small statures due to delayed maturation of the skeletal system and their muscle tone is poor.

They have a characteristic face appearance. It is broad and flat with a small nose ,irregular teeth, abnormally shaped ears and thick lips .

Many of them have peculiar small fold of skin across this inner part of the eye this gives the eyes a slightly oriental look. The name “mongolism” is derived from this characteristic .

The physiological symptoms

They have large furrowed tongue.

40%of children with the syndrome have major heart defects.

Defects of kidneys ,thyroid gland and Adrenal glands are so common with this syndrome.

Some highly usual dermatoglyphic (glyphic=craving) patterns of hand creases ,fingerprints and foot prints are also associated with this syndrome.

Hipbones are abnormally shaped and the feet's little fingers often short and curved inward.

Males have poorly developed genitals and Are invariably sterile,in females ovarian defects and irregular menstruation but fertility is possible.

Many children learn to talk but speech is usually thick and harsh sounding ,perhaps in part because of hearing defects.

Edwards syndrome(trisomy18)

This syndrome affects about one in 4,500 Live-born children.

Approximately 65 % of those individuals are females ,males with the syndrome are more likely to undergo spontaneous abortion.

Karyotype:(47,XX or XY+18) means having extra 18 chromosome.

Symptoms

They have multiple abnormalities including severe mental and physical retardation.

Such as :1-elongated skull with low set

malformed ,sometimes pointed ears ,their jaw and oral cavity is small .

2-They carry their fingers in an abnormal position with the second finger overlapping the third.

Life expectancy of males is about 3 months ,in affected females it is about nine months.

Trisomy 16 (47,xx or xy+16)

Virtually no live –born babies having trisomy 16 are seen, cause this trisomy is often encountered in early abortuses

Karyotype:47 chromosome including

an extra chromosome which is chromosome number 16

Patau’s syndrome(trisomy 13)

It occurs in about one in 5,000 live births.

Affected children rarely survive more than3-4 moths after birth .

Karyotype: (47, XX or XY +13) Having

extra 13 chromosome is the reason for that abnormality.

Affected children are severely retarded both mentally and physically.

Physical symptoms

Small skull and eyes.

The ears are often malformed and deafness in common.

Many have malformed thumbs and extra digits.

70%have heart defects.

Sexual Aneuploidy

A chromosome abnormality that causes individuals to have an abnormal number of chromosomes is called aneuploidy. If the zygote has an additional chromosome (three instead of two) it is trisomic for that chromosome. If the zygote is missing a chromosome it is monosomic. Aneuploid cells occur as a result of chromosome breakage or nondisjunction errors that happen during meiosis. Two types of errors occur during nondisjunction: homologous chromosomes don't separate during anaphase I of meiosis I or sister chromatids don't separate during anaphase II of meiosis II. 

In sex chromosomes, nondisjunction results in a number of abnormalities. Klinefelter syndrome is a disorder in which males have an extra X chromosome. The genotype for males with this disorder is XXY. People with Klinefelter syndrome may also have more than one extra chromosome resulting in genotypes which include XXYY, XXXY, and XXXXY. Other mutations result in males that have an extra Y chromosome and a genotype of XYY. These males were once thought to be taller than average males and overly aggressive based on prison studies. Additional studies however have found XYY males to be normal. Tuner syndrome is a condition that affects females. Individuals with this syndrome, also called monosomy X, have a genotype of only one X chromosome (XO). Trisomy X females have an additional X chromosome and are also referred to as metafemales (XXX).

Nondisjunction can occur in autosomal cells as well. Down syndrome is most commonly the result of nondisjunction affecting autosomal chromosome 21. Down syndrome is also referred to as trisomy 21 because of the extra chromosome.

TURNER’S SYNDROME

 45 XO, encompasses several conditions in human females, of which monosomy X (absence of an entire sex chromosome, the Barr body) is most common. It is a chromosomal abnormality in which all or part of one of the sex chromosomes is absent (unaffected humans have 46 chromosomes, of which two are sex chromosomes). Normal females have two X chromosomes, but in Turner syndrome, one of those sex chromosomes is missing or has other abnormalities.

KLINEFELTER’S SYNDROME

47, XXY, or XXY syndrome is a condition in which human males have an extra X chromosome. While females have an XX chromosomal makeup, and males an XY, affected individuals have at least two X chromosomes and at least one Y chromosome. Because of the extra chromosome, individuals with the condition are usually referred to as "XXY Males", or "47, XXY Males"

JACOB’S SYNDROME

XYY syndrome is an aneuploidy (abnormal number) of the sex chromosomes in which a human male receives an extra Y-chromosome, giving a total of 47 chromosomes instead of the more usual 46. This produces a 47,XYY karyotype which occurs in 1 in 1000 male births.

Some medical geneticists question whether the term "syndrome" is appropriate for this condition[ because its clinical phenotype is norma and the vast majority (an estimated 97% in Britain) of 47,XYY males do not know their karyotype.

Metafemale

Triple X syndrome is a form of chromosomal variation characterized by the presence of an extra X chromosome in each cell of a human female. The condition always produces females, with an XX pair of chromosomes, as well as an additional chromosome, resulting in the formation of XXX.