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  • 1
    Abstract: The human X chromosome has a unique biology that was shaped by its evolution as the sex chromosome shared by males and females. We have determined 99.3% of the euchromatic sequence of the X chromosome. Our analysis illustrates the autosomal origin of the mammalian sex chromosomes, the stepwise process that led to the progressive loss of recombination between X and Y, and the extent of subsequent degradation of the Y chromosome. LINE1 repeat elements cover one-third of the X chromosome, with a distribution that is consistent with their proposed role as way stations in the process of X-chromosome inactivation. We found 1,098 genes in the sequence, of which 99 encode proteins expressed in testis and in various tumour types. A disproportionately high number of mendelian diseases are documented for the X chromosome. Of this number, 168 have been explained by mutations in 113 X-linked genes, which in many cases were characterized with the aid of the DNA sequence
    Type of Publication: Journal article published
    PubMed ID: 15772651
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  • 2
    Publication Date: 2012-03-01
    Description: The human X and Y chromosomes evolved from an ordinary pair of autosomes during the past 200-300 million years. The human MSY (male-specific region of Y chromosome) retains only three percent of the ancestral autosomes' genes owing to genetic decay. This evolutionary decay was driven by a series of five 'stratification' events. Each event suppressed X-Y crossing over within a chromosome segment or 'stratum', incorporated that segment into the MSY and subjected its genes to the erosive forces that attend the absence of crossing over. The last of these events occurred 30 million years ago, 5 million years before the human and Old World monkey lineages diverged. Although speculation abounds regarding ongoing decay and looming extinction of the human Y chromosome, remarkably little is known about how many MSY genes were lost in the human lineage in the 25 million years that have followed its separation from the Old World monkey lineage. To investigate this question, we sequenced the MSY of the rhesus macaque, an Old World monkey, and compared it to the human MSY. We discovered that during the last 25 million years MSY gene loss in the human lineage was limited to the youngest stratum (stratum 5), which comprises three percent of the human MSY. In the older strata, which collectively comprise the bulk of the human MSY, gene loss evidently ceased more than 25 million years ago. Likewise, the rhesus MSY has not lost any older genes (from strata 1-4) during the past 25 million years, despite its major structural differences to the human MSY. The rhesus MSY is simpler, with few amplified gene families or palindromes that might enable intrachromosomal recombination and repair. We present an empirical reconstruction of human MSY evolution in which each stratum transitioned from rapid, exponential loss of ancestral genes to strict conservation through purifying selection.〈br /〉〈br /〉〈a href="" target="_blank"〉〈img src="" border="0"〉〈/a〉   〈a href="" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hughes, Jennifer F -- Skaletsky, Helen -- Brown, Laura G -- Pyntikova, Tatyana -- Graves, Tina -- Fulton, Robert S -- Dugan, Shannon -- Ding, Yan -- Buhay, Christian J -- Kremitzki, Colin -- Wang, Qiaoyan -- Shen, Hua -- Holder, Michael -- Villasana, Donna -- Nazareth, Lynne V -- Cree, Andrew -- Courtney, Laura -- Veizer, Joelle -- Kotkiewicz, Holland -- Cho, Ting-Jan -- Koutseva, Natalia -- Rozen, Steve -- Muzny, Donna M -- Warren, Wesley C -- Gibbs, Richard A -- Wilson, Richard K -- Page, David C -- R01 HG000257/HG/NHGRI NIH HHS/ -- R01 HG000257-17/HG/NHGRI NIH HHS/ -- U54 HG003273/HG/NHGRI NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2012 Feb 22;483(7387):82-6. doi: 10.1038/nature10843.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, Massachusetts 02142, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Chromosomes, Human, Y/*genetics ; Conserved Sequence/*genetics ; Crossing Over, Genetic/genetics ; *Evolution, Molecular ; Gene Amplification/genetics ; *Gene Deletion ; Humans ; In Situ Hybridization, Fluorescence ; Macaca mulatta/*genetics ; Male ; Models, Genetic ; Molecular Sequence Data ; Pan troglodytes/genetics ; Radiation Hybrid Mapping ; Selection, Genetic/genetics ; Time Factors ; Y Chromosome/*genetics
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    ISSN: 1573-2665
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 28-year-old man with classical phenylketonuria had increased seizure frequency and rapidly progressive spasticity. There was a marked reduction of biogenic amine neutotransmitter metabolites in cerebrospinal fluid. Dietary therapy reduced serum phenylalanine levels, improved symptoms of hypertonicity, and cerebrospinal fluid neurotransmitter metabolites became normal. An adolescent male with classical phenylketonuria, treated by dietary restriction until age 6 years, was assessed for decreasing school performance at 18 years. Cerebrospinal fluid biogenic amine neurotransmitter metabolites were significantly reduced. Magnetic resonance imaging in both subjects showed multiple areas of increased signal intensity in cerebral white matter. Neuropathological changes in classical phenylketonuria have been characterized as a dysmyelinating or demyelinating process. Neurochemical studies show a defect in brain lipids and biogenic amine metabolism. In the past, dietary therapy was directed at reducing hyperphenylalaninaemia only during the first decade of life. This report, as well as other studies, indicates that dietary therapy should be lifelong in patients with classical phenylketonuria, in order to prevent progressive and insidious neurological deterioration in later life.
    Type of Medium: Electronic Resource
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