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An abnormal number of chromosomes is known as aneuploidy, and occurs when an individual is either missing a chromosome from a pair (resulting in monosomy) or has more than two chromosomes of a pair (trisomy, tetrasomy, etc.).
The following is a list of genetic disorders and if known, type of mutation and for the chromosome involved. Although the parlance "disease-causing gene" is common, it is the occurrence of an abnormality in the parents that causes the impairment to develop within the child.
Chromosomes in Down syndrome, the most common human condition due to aneuploidy. There are three chromosomes 21 (in the last row). A chromosomal disorder is a missing, extra, or irregular portion of chromosomal DNA. [33] It can be from an atypical number of chromosomes or a structural abnormality in one or more chromosomes.
Sex chromosome anomalies belong to a group of genetic conditions that are caused or affected by the loss, damage or addition of one or both sex chromosomes (also called gonosomes). In humans this may refer to: 45, X, also known as Turner syndrome; 45,X/46,XY mosaicism, also known as X0/XY mosaicism and mixed gonadal dysgenesis; 46, XX/XY
The abnormal cells may have only one X (45,X) or they may be affected by one of several types of partial monosomy like a deletion of the short p arm of one X chromosome (46,X,del(Xp)) or the presence of an isochromosome with two q arms (46,X,i(Xq)) [70] Turner syndrome has distinct features due to the lack of pseudoautosomal regions, which are ...
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.
These abnormalities can disrupt the normal function of genes involved in cell cycle regulation, leading to uncontrolled cell growth and tumor formation. [16] The chromosome theory of cancer is a long-standing idea originated from the work of Theodor Boveri, a German biologist, in the early 20th century.
One of them consists in micro-deletions of the chromosome region 15q11–q13. 70% of patients present a 5–7-Mb de novo deletion in the proximal region of the paternal chromosome 15. The second frequent genetic abnormality (~ 25–30% of cases) is maternal uniparental disomy of chromosome 15.