Question

turner syndrome Genetic basis and inheritance patterns of the disease, with a description of that type of inheritance

Answer 1

Turner syndrome with its genetic basis: This condition is caused by a female having one normal X chromosome in each of her cells, while the other sex chromosome is either missing or structurally abnormal. Females without Turner syndrome have 2 full X chromosome in all of their cells, and males have one X chromosome and one Y chromosome .Turner syndrome  is a sex aneuploidy syndrome, exclusively among females, in which a single X chromosome is present (45,XO). (Aneuploidy is acondition in which an organism does not have the normal number of chromosomes. If there is 1 less chromosome, this is referred to as monosomic, abbreviated as 2n - 1. If there is 1 extra chromosome, this is called trisomic, abbreviated as 2n + 1. Examples of aneuploidy are trisomy 21 and XYY Klinefelter's Syndrome) .Other names for Turner's syndrome are monosomy X, 45X and Ullrich-Turner syndrome.

Most commonly, Turner syndrome occurs due to a random event during the formation of an egg or sperm cell in a parent (prior to conception).It is a genetic condition found in females only. It affects about 1 in every 2,500 girls. Girls who have this condition usually are shorter than average and infertile due to early loss of ovarian function.

Turner syndrome can cause a variety of medical and developmental problems, including short height, failure development of ovaries and heart defects.Turners syndrome is associated with a 3-fold increase in overall mortality and a life expectancy, whch is reduced by up to 13 years. Almost all women are infertile, although  pregnancy with donor embryos may be possible. Having appropriate medical treatment and support allows a woman with Turner syndrome to lead a normal, healthy and happy life.The clinical phenotype is highly variable and includes short stature, gonadal dysgenesis, pterygium colli, cubitus valgus and low hairline.

Types:There are 2 types of Turner syndrome: monosomy X TS and mosaic TS.

About half of all girls with Turner syndrome have a monosomy disorder. Monosomy means that a person is missing one chromosome in the pair.

Mosaic Turner syndrome  is a condition in which cells inside the same person have different chromosome packages. This condition  can affect any cell in the body. Some cells have X chromosomes and some don't.

Inheritance pattern :Turner syndrome is not usually inherited in families. Turner syndrome occurs when one of the two X chromosomes normally found in women is missing or incomplete. Although the exact cause of Turner syndrome is not known, this appears to occur as a result of a random error during the formation of either the eggs or sperm When this condition results from monosomy X , the chromosomal abnormality happens as a random event during the formation of reproductive cells (eggs and sperm) in the affected person's parent. An error in cell division which is called nondisjunction can result in reproductive cells with an abnormal number of chromosomes. i.e .an egg or sperm cell may lose a sex chromosome as a result of nondisjunction. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have a single X chromosome in each cell and will be missing the other sex chromosome.