User:Abhirupa 2000/Gene dosage

Summary of changes to gene dosage article
The gene dosage article is quite short, basically just a lead paragraph. It gives a rather perfunctory overview of the concept but it doesn’t delve into specifics of why gene dosage is relevant to health and proper development. There are also a few statements that seem wrong, such as, “In eukaryotes, most genes found in the cell are expressed as autosomal genes and are found in two copies.” Domain Eukarya encompasses many organisms, like plants, that are not diploids. Concepts such as polyploidy and hybridization fit in well within this topic and can be explored further, especially to diversify topics outside of human development. The current article also mentions Down syndrome in passing, but this concept likely needs to be explored further in the context of gene dosage since it is so important for the genotypic development of Down syndrome. Gene dosage errors are also implicated in other disorders such as Turner syndrome and Klinefelter syndrome, which should be explored as well. The last paragraph of the current article mentions binary fission in bacteria, but this topic doesn’t really seem to align with the definition of gene dosage provided. This paragraph is likely unnecessary and should be removed.

New sections to be added: Turner Syndrome, Klinefelter Syndrome, Down Syndrome

Turner syndrome:


 * Link to Turner syndrome article for definitions and phenotypes
 * Gene dosage has been shown to play an important role in the severity of TS-specific symptoms; individuals that have a higher concentration of cells with two X chromosomes tend to have less severe symptoms than those who have more cells with a singular X chromosome (Bondy 2009)
 * A potential graphic could help demonstrate X/XX mosaicism, where some cells in the body have a single X chromosome but the others have two
 * In females with two X chromosomes, at least one X chromosome in each cell gets inactivated, a phenomenon known as X-inactivation. Most of the genotype contribution from the inactivated X chromosome gets lost. However, there are some genes that get expressed from the inactivated and the active X chromosome, termed “X-escapees”.
 * A gene of interest within this region is the STS gene, which codes for a protein crucial to steroid processing in cells. In mice studies, individuals with lower than baseline levels of the sts protein exhibit neurobehavioral symptoms that are included within the Turner syndrome symptom panel, such as hyperactivity and “anxiety-related and perseverative behavior.

Klinefelter syndrome:


 * Link to Klinefelter syndrome article for definitions and phenotypes
 * Overexpression of X chromosome products has been implicated as a cause of Klinefelter syndrome, so it may be affiliated with overdosage of “X-escapees” such as STS (steroid hormone pathways), which is expressed higher in female (XX) tissues than male (XY tissues)
 * Description of the Klinefelter-symptoms seen when X-escapee NLGN4X is overexpressed

Down syndrome:


 * Link to Down syndrome article for definitions and phenotypes
 * Genes on chromosome 21 (Down syndrome is most commonly affiliated with three copies of chromosome 21, known as trisomy 21) that have been studied for haploinsufficiency: two copies of the gene are necessary for a normal phenotype. Haploinsufficent genes are also highly susceptible to problems due to trisomy, so they could be the causal factors for Down syndrome phenotype
 * Really good figure of demonstrating likelihood of genes on chromosome 21 being haploinsufficient, which could potentially be used in the article?