TY - JOUR T1 - X-Chromosome and Abnormalities AU - Ozaslan, Mehmet AU - Bayıl Oguzkan, Sibel PY - 2020 DA - June JF - The Eurasia Proceedings of Science Technology Engineering and Mathematics JO - EPSTEM PB - ISRES Publishing WT - DergiPark SN - 2602-3199 SP - 9 EP - 12 VL - 9 LA - en AB - This research investigates the function of the X chromosome and its different abnormalities on humans, including data from comparative genome analysis of other organisms. The X chromosome has many fatures that are unique in the human genome. Females inherit an X chromosome. Gene expression on one of the female X chromosomes is silenced early in development by the process of X-chromosome inactivation (XCI), and this chromosome remains inactive in somatic tissues thereafter. In the female germ line, the inactive chromosome is reactivated and undergoes meitotic recombination with the second X chromosome. The male X chromosome fails to recombine along virtually its entire length during meiosis: instead, recombination is restricted to short regions at the tips of the X chromosome arms that recombine with equivalent segments on the Y chromosome. Genes inside these regions are shared between the sex chromosomes, and their behaviour is therefore described as ‘pseudoautosomal’. Genes outside these regions of the X chromosome are strictly X-linked, and the vast majority are present in a single copy in the male genome. The unique properties of the X chromosome are a consequence of the evolution of sex chromosomes in mammals. The sex chromosomes have evolved from a pair of autosomes within the last 300 million years. In the process, the original, functional element have been conserved on the X chromosome, but the Y chromosome has lost almost all traces of the ancestral autosome, including the genes that were once shared with the X chromosome. The hemizygosity of males for almost all X chromosome genes exposes recessive phenotypes, yhus accounting for the large number of diseases that have been associated with the X chromosome.The biological consequences of the sex chromosome evolution account fort the intense interest in the human X chromosome in recent decades. However, evolutionary processes are likely to have shaped the behaviour and structure of the X chromosome in many the ways, influencing features such as repeat content, mutation rate, gene content and haplotype structure. The availability of the finished sequence of the human X chromosome, described here, now allows us to explore its evolution and unique properties at a new level. KW - X chromosome KW - XCI KW - Y chromosom CR - NHGRI. 2006. Chromosome Abnormalities Archived 2006-09-25 at the Wayback Machine Rieger, R.; Michaelis, A.; Green, M.M. (1968). "Mutation". A glossary of genetics and cytogenetics: Classical and molecular. New York: Springer-Verlag. Santaguida, Stefano; Amon, Angelika (2015-08-01). "Short- and long-term effects of chromosome mis-segregation and aneuploidy". Nature Reviews Molecular Cell Biology. 16 (8): 473–485. Templado C, Uroz L, Estop A (2013). "New insights on the origin and relevance of aneuploidy in human spermatozoa". Mol. Hum. Reprod. 19 (10): 634–43. "Atlas of Genetics and Cytogenetics in Oncology and Haematology". atlasgeneticsoncology.org. Archived from the original on 2011-02-23. Baarends WM, van der Laan R, Grootegoed JA (2001). "DNA repair mechanisms and gametogenesis". Reproduction. 121 (1): 31–9. Jump up to: a b Marchetti F, Bishop J, Gingerich J, Wyrobek AJ (2015). "Meiotic interstrand DNA damage escapes paternal repair and causes chromosomal aberrations in the zygote by maternal misrepair". Sci Rep. 5: 7689. UR - https://dergipark.org.tr/en/pub/epstem/issue//759567 L1 - https://dergipark.org.tr/en/download/article-file/1174338 ER -