Search results
Results from the WOW.Com Content Network
Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with developmental delays, mild to moderate intellectual disability , and characteristic physical features.
Down syndrome is a chromosomal abnormality characterized by the presence of an extra copy of genetic material on chromosome 21, either in whole (trisomy 21) or part (such as due to translocations). The effects of the extra copy varies greatly from individual to individual, depending on the extent of the extra copy, genetic background ...
Trisomy refers to the presence of three copies, instead of the normal two, of a particular chromosome. The presence of an extra chromosome 21, which is found in Down syndrome, is called trisomy 21. Trisomy 18 and Trisomy 13, known as Edwards syndrome and Patau syndrome, respectively, are the two other autosomal trisomies recognized in live-born ...
"Full trisomy", also called "primary trisomy", means that an entire extra chromosome has been copied. "Partial trisomy" means that there is an extra copy of part of a chromosome. "Secondary trisomy" - the extra chromosome has quadruplicated arms (the arms are identical; it is an "isochromosome").
Changes to chromosome 21 include a missing segment of the chromosome in each cell (partial monosomy 21) and a circular structure called ring chromosome 21. A ring chromosome occurs when both ends of a broken chromosome are reunited.
Isochromosome in which the arms are mirror copies of each other. An isochromosome is an unbalanced structural abnormality in which the arms of the chromosome are mirror images of each other. [1] The chromosome consists of two copies of either the long (q) arm or the short (p) arm because isochromosome formation is equivalent to a simultaneous ...
Trisomy 8 mosaicism affects wide areas of chromosome 8, containing many genes, and can thus be associated with a range of symptoms. Mosaic trisomy 8 has been reported in rare cases of Rothmund–Thomson syndrome, a genetic disorder associated with the DNA helicase RECQL4 on chromosome 8q24.3. The syndrome is "characterized by skin atrophy ...
Affected people have two copies of chromosome 13, plus extra material from chromosome 13 attached to another chromosome. With a translocation, the person has a partial trisomy for chromosome 13 and often the physical signs of the syndrome differ from the typical Patau syndrome. [citation needed]
Monosomy. Schematic karyogram of a human, showing the normal diploid karyotype. It shows annotated bands and sub-bands as used for the nomenclature of chromosome abnormalities including partial monosomies. It shows 22 homologous chromosomes, both the female (XX) and male (XY) versions of the sex chromosome (bottom right), as well as the ...
Karyotype. A karyotype is the general appearance of the complete set of chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. [1] [2] Karyotyping is the process by which a karyotype is discerned by determining the chromosome complement of an individual, including the number of ...