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Down Syndrome and Chromosomes Yujen “Ted” Hsia Emeritus Professor  Cell & Molecular Biology and Pediatrics WCCC Total Life Recovery Program Tuesday 30 June 2009
Let Us Pray ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Amen .
What Did We Learn Last Time? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Down Syndrome ,[object Object],[object Object],[object Object],[object Object],Basic Cytogenetics ,[object Object],[object Object],[object Object],[object Object]
John Langdon Down 1828-1896 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],http://www.disabilities-us.com/slaterfamily/JLD.htm
Boy with Down Syndrome http://www.sahha.gov.mt/pages.aspx?page=497 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
The Eye in Down Syndrome www.vam.ac.uk/images/image/37537-popup.html ,[object Object],[object Object],[object Object],[object Object]
Simian Crease in Down Syndrome ,[object Object],[object Object],[object Object],[object Object],http://medgen.genetics.utah.edu/photographs/diseases/high/peri005.jpg ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Down Syndrome, Trisomy 21 ,[object Object],[object Object],[object Object],[object Object],[object Object]
Redundant Skin at the Nape of the Neck in Down Syndrome ,[object Object],[object Object]
Down Syndrome:  Complications in Childhood  ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],http://www.path.cam.ac.uk/~part1/lectures/gd4/gd4c.html
Down Syndrome:  Intellectual Development ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],http://www.path.cam.ac.uk/~part1/lectures/gd4/gd4c.html
[object Object],[object Object],Developmental Milestones In Down Syndrome
Behavior in Down Syndrome ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],http://www.path.cam.ac.uk/~part1/lectures/gd4/gd4c.html
Special Olympics ,[object Object],[object Object],[object Object],[object Object],[object Object],http://njmonthly.com/articles/towns_and_schools/steve-adubato-only-in-nj/steve-adubato-atypical-inspiration-.html ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Health Issues in Later Life ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Down Syndrome:  Epidemiology ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],http://www.path.cam.ac.uk/~part1/lectures/gd4/gd4c.html
Normal Human Chromosomes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Human Cells ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],http://www.accessexcellence.org/AB/GG/mammal_Types_2.html sperm Egg with sperm drawn to scale
Human Chromosomes ,[object Object],[object Object],[object Object],[object Object],http://www.peeron.com/inv/parts/x488c02 http://kosmoi.com/Space/Shuttle/Pictures/028.jpg www.n30ew.com/ Threeweekstogo.htm ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Electron Microscopy of Cell Nucleus ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],http://www.geocities.com/Colosseum/Arena/7982/1.html Nuclear membrane Euchromatin Heterochromatin Nucleolus ,[object Object],[object Object],[object Object],[object Object]
The Chromatin in Chromosomes has Complex Structure. ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Chromatin Packaging http://www.accessexcellence.org/AB/GG/chroma_packg.html DNA   double helix “ Beads on a string” Packed nucleosomes Extended   chromatin Condensed chromatin Chromatid arms DNA can be packed  x  50,000. nm 2 11 30 300 1400 700 It becomes condensed for cell division. The genes in DNA can only be active when not condensed. X -shaped chromosomes are formed before cell division.
The Parts of a Chromosome ,[object Object],Centromere p  (short arm) q  (long arm) Satellites Telomere Chromatids chromatid  arms are short ( p ) ,[object Object],or long ( q ). ,[object Object],Satellites  contain multiple copies of RNA genes. ,[object Object],Telomere These have key functions. p q
G-Banded Metaphase Chromosomes faculty.mwsu.edu/biology/jon.scales/Courses/.../aberrations. ppt   Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Centromere ,[object Object],[object Object],[object Object],Satellites Variable Regions
Q Banded Chromosomes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Female . None . None . 46. Probably Normal Female . 46, XX . Diagnosis? No . XX .
SKY Bands ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],http://www.chroma.com/image-1.html
“ Painted” Chromosomes Spectral Karyotype [SKY] ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],XY , Male . 0. 0. 46. Probably Normal Male . 46, XY . Diagnosis? None .
Mitosis ,[object Object],[object Object],[object Object],Prophase Metaphase Anaphase Telophase ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],S   phase ,[object Object],[object Object]
Breakage-Reunion ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],chiasma chiasma centromere centromere chromatid
Chromosome Number (N) in Meiosis and Mitosis ,[object Object],[object Object],[object Object],[object Object],[object Object],http://www.dac.neu.edu/biology/d.scheirer/mitosis_meiosis.gif Meiosis I N N 2 N 2 N 2 N 2 N N N N N Mitosis  Meiosis II
Chromosomal Errors ,[object Object],[object Object],[object Object],Errors in Number Errors in Structure ,[object Object],[object Object],[object Object],[object Object],[object Object],, to the cell or the organism.
Meiotic Non-Disjunction http://www.erin.utoronto.ca/~w3bio380/Lectsked/Lect04/Egg2.htm Meiosis I II 24  22 Non-disjunction Normal Non-disjunction Normal Normal Normal Maternal 21 Paternal 21 23  23 24  24 22  22
Chromosomes in Spontaneous Abortion At least 15% of first trimester pregnancies are lost. 50% Normal 50% Abnormal 46, N + 16 45, X triploidy other other autosomal trisomies
A G Banded Karyotype ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],XY . 0. 16 . 47. ,[object Object],[object Object],47, XY ,+ 16 . No . http://www.pathology.washington.edu/Cytogallery/cytogallery.html Male .
Trisomy 21 in Down Syndrome 24,X,+21 23,Y 47,XY,+21 Egg, extra  21 Sperm, normal Zygote Extra 21 Trisomy 21
Down Syndrome:  Genetic Basis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],http://www.path.cam.ac.uk/~part1/lectures/gd4/gd4c.html
A G Banded Karyotype ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Female . 0. 21 . 47. Trisomy  21 , Down syndrome. 47, XX ,+ 21 . Diagnosis? No . http://www.pathology.washington.edu/Cytogallery/cytogallery.html
Origin of the Extra 21 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],http://prx.hml.org:2055/das/book/11709583/view/873   Father Mother Child ( Meiosis II  error.)
A Finite Number of Eggs in a Woman ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],http://www.erin.utoronto.ca/~w3bio380/Lectsked/Lect04/Egg2.htm Germs cells Millions 1.0 Months post conception Years post birth Birth 0  3  6  9  10  30  50 0.5 3.0 6.0 9.0 Number of Eggs in a Human Ovary by Maternal Age
[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Maternal Age and Trisomy 21 Incidence per 1,000 births 20  25  30  35  40  45 Maternal Age 20 15 10 5
Chromosome Testing by FISH ,[object Object],[object Object],[object Object],http://www.kumc.edu/instruction/medicine/pathology/ed/ch_6/Persons%20Chromosome%20abnormalities.ppt ,[object Object],[object Object],[object Object],X 18 Y 13 21
Down Syndrome Mosaicism ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],47,XY+21/46,XY
Mosaicism What is it? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Robertsonian Translocations Two acrocentrics Breaks occur at the  centromere  of both acrocentrics. The  q  arms fuse (Acrocentric  p  satellites have similar repetitive  genes, loss of some satellites has no clinical  importance). The  p  arms fuse 21  21   14  14   rbt ( 14q / 21q ) rbt ( 14p / 21p ) The fused  p  arms are lost.   In effect, a  21  has fused with a  14 .
Risk for Down Syndrome if a Parent is a Translocation Carrier ,[object Object],Normal Parent “ Carrier” Parent Normal Carrier + 21 - 14 - 21 + 14
What Do These Chromosomes Show? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],XY ,  Male . 14 ,  21 . 14p +. 45. Normal Male with balanced 45, XY , - 14 , - 21 , rbt( 14q / 21q) . Diagnosis? http://medgen.genetics.utah.edu/photographs/diseases/high/69b.gif 14q / 21q . Robertsonian  14 / 21  “carrier.”
What Do These Chromosomes Show? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],XY ,  Male . 14 . 14p +. 46. Down syndrome male with imbalanced  46, XY , - 14 , +rbt( 14q / 21q ). Diagnosis? http://medgen.genetics.utah.edu/photographs/diseases/high/69b.gif 14q / 21q . Robertsonian ( 14q / 21q ), equivalent to extra  21 .
A Q Banded Karyotype ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],This almost always arises  de novo . XX ,  Female . 21 . rbt( 21q / 21q ). 46. Down syndrome . 46, XX, - 21 ,+ 21q / 21q .
[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],A Q Banded Karyotype 45, XX , - 21 - 21 , +rbt( 21q / 21q ). She cannot have a normal baby. Female . 21 ,   21 . rbt ( 21q / 21q ). 45. Normal . 21q / 21q   “Carrier.”
What Do These Chromosomes Show? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],XXY . 0. 23   chromosomes . 69. Triploidy . 69, XXY . Diagnosis? http://www.tokyo-med.ac.jp/genet/cki-e.htm ,[object Object],[object Object],No . Male .
What Do These Chromosomes Show? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Female . No  Y . X  or  Y . 0. 45. Turner  syndrome, in a liveborn girl.  45, X . Diagnosis? http://www.tokyo-med.ac.jp/genet/cki-e.htm None . > 98% of 45, X  are lost  in utero .
Turner Syndrome ,[object Object],[object Object],[object Object],[object Object],[object Object],http://medgen.genetics.utah.edu/photographs/pages/turner_syndrome.htm ,[object Object],[object Object],[object Object],[object Object]
What Do These Chromosomes Show? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Female . 0. 13 . 47. Trisomy  13 .  Few are live-born, 47, XX ,   + 13 . Diagnosis? http://medgen.genetics.utah.edu/photographs/diseases/high/69b.gif No . and very few survive.
What Do These Chromosomes Show? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Male . 0. 18 . 47. Trisomy  18 . Few are live-born, 47, XX , + 18 . Diagnosis? http://medgen.genetics.utah.edu/photographs/diseases/high/69b.gif No . and very few survive.
What Do These Chromosomes Show? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],XXY ,  Male . 0. X  or  Y . 47. Klinefelter  syndrome. 47, XXY . Diagnosis? None . http://www.tokyo-med.ac.jp/genet/cki-e.htm
What Do These Chromosomes Show? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],XYY ,  Male . 0. Y . 47. This is usually benign. 47, XYY . Diagnosis? None . http://www.tokyo-med.ac.jp/genet/cki-e.htm
48,XXYY 47,XYY
What is the Inheritance Pattern? ,[object Object],[object Object],I II III IV ,[object Object],? ? Balanced translocation This is an imbalanced chromosomal translocation.  Imbalanced   fetus ,[object Object],1  2  3  4  5  6  7  8 1  2  3  4  5  6  1  2 1  2  3  4  5  6 Could the abortions be a clue?
Next Time ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
 
 
Maternal Serum   -Fetoprotein http://www.obgyntoday.org/previous%20conf%20understanding%20AFP.htm AFP Concentration Pregnant women Normal Down syndrome

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Down Syndrome and Chromosomes

  • 1. Down Syndrome and Chromosomes Yujen “Ted” Hsia Emeritus Professor Cell & Molecular Biology and Pediatrics WCCC Total Life Recovery Program Tuesday 30 June 2009
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  • 23. Chromatin Packaging http://www.accessexcellence.org/AB/GG/chroma_packg.html DNA double helix “ Beads on a string” Packed nucleosomes Extended chromatin Condensed chromatin Chromatid arms DNA can be packed x 50,000. nm 2 11 30 300 1400 700 It becomes condensed for cell division. The genes in DNA can only be active when not condensed. X -shaped chromosomes are formed before cell division.
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  • 33. Meiotic Non-Disjunction http://www.erin.utoronto.ca/~w3bio380/Lectsked/Lect04/Egg2.htm Meiosis I II 24 22 Non-disjunction Normal Non-disjunction Normal Normal Normal Maternal 21 Paternal 21 23 23 24 24 22 22
  • 34. Chromosomes in Spontaneous Abortion At least 15% of first trimester pregnancies are lost. 50% Normal 50% Abnormal 46, N + 16 45, X triploidy other other autosomal trisomies
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  • 36. Trisomy 21 in Down Syndrome 24,X,+21 23,Y 47,XY,+21 Egg, extra 21 Sperm, normal Zygote Extra 21 Trisomy 21
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  • 45. Robertsonian Translocations Two acrocentrics Breaks occur at the centromere of both acrocentrics. The q arms fuse (Acrocentric p satellites have similar repetitive genes, loss of some satellites has no clinical importance). The p arms fuse 21 21 14 14 rbt ( 14q / 21q ) rbt ( 14p / 21p ) The fused p arms are lost. In effect, a 21 has fused with a 14 .
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  • 63. Maternal Serum  -Fetoprotein http://www.obgyntoday.org/previous%20conf%20understanding%20AFP.htm AFP Concentration Pregnant women Normal Down syndrome

Hinweis der Redaktion

  1. Diffuse plaques of Ab42 begin to form by age 14. In the late 20’s, these form specific plaques with accrual of Ab40. Neurofibrillary tangles appear by the 30’s
  2. Photograph from:http://www.nas.com/downsyn/donations.html
  3. A Nucleus has DNA, RNA, Nucleous, Protein, Euchromatin, Heterochromatin
  4. CHROMOSOMAL RAINBOWS: NOVEL MULTIBAND PATH FILTER SETS FOR FLUOESCENCE MICROSCOPY ALLOW RAPID MAPPING OF CHROMOSOMAL REARRANGEMENTS BY IMAGING A PANEL OF 16 INDIVIDUALLY LABELED LOCUS-SPECIFIC DNA PROBES WHICH BIND EVERY 8-10 MEGABASEPAIRS ALING HUMAN CHROMOSOME 10. Benjamin O'Brien and H.-Ulli Weier, University of California, E.O. Lawrence Berkley National Laboratory, Berkeley, CA
  5. Non-disjunction leads to abnormal chromosome numbers If one daughter gamete has extra chromosome (i.e., 24 rather than the normal 23) the syndrome is called trisomy (3 copies of the same chromosome) at fertilization e.g., Down Syndrome--trisomy 21: this is due to an extra copy of chromosome 21 If the daughter gamete has 1 less chromosome (i.e., a total of 22 rather than the normal 23) it is referred to as monosomy (e.g., Turner Syndrome--lacks sex chromosome) Most cases of monosomy are not viable .
  6. Richard Hall BSc SRCS. Cytogenetics Department, Guy's & St. Thomas' NHS Foundation Trust. TRISOMY FOR ALL C’SOMES SEEN (EXCEPT 1) – ACCOUNTS FOR 60% OF ALL ABNORMALITIES MOST COMMON T16 AND 45,X (APPROX 20%) POLYPLOIDY (MOSTLY TRIPLOIDY) 15% REMAINING ABNORMALITIES (5%) ARE MOSTLY STRUCTURAL REARRANGEMENTS
  7. Berman: Nelson’s Pediatrics Ed 16, 2000. Judith G. Hall: Genetic Diseases. P. 329 Figure 78-4 Partial karyotypes from patients with Down syndrome. A, Patient with trisomy 21. B, Chromosome 21 from two patients and their parents. Left: Two of a patient's chromosomes with brightly fluorescent satellites were transmitted by the mother. Right: Another patient's two chromosomes with bright satellites resulted from paternal nondisjunction at second meiotic division. C, 21q21q translocation. D, 14q21q translocation in a mother (above) and her affected child (below).
  8. Increases to ~7 million by 6 months in utero Then # decreases due to apoptosis Only ~2 x 10 6 at birth ~0.5 x 10 6 at puberty Continual decline until menopause: ovulation and death.
  9. http://www.uptodate.com/online/content/image.do?imageKey=hema_pix/robertso.htm&title=Robertsonian%20translocation
  10. Understanding Maternal Serum Screening Lecturer: Alberto de la Vega MD, FACOG, RDMS Associate Professor of Obstetrics and Gynecology, University of Puerto Rico School of Medicine The purpose of this conference is to provide you with an understanding of the concepts behind risk assessment for both open neural tube defects (ONTD’s) and Down’s syndrome (DS) based on maternal serum screening. Alfa feto protein: · Evaluation of alfa feto protein (AFP) started the era of prenatal screening in the 1970’s. · 1972: Brock & Sutcliffe reported that measurement of an abnormally elevated value of AFP in Amniotic fluid (AF) was useful for diagnosis of ONTD’s · 1974: Wald et al and Brock et al in 2 articles published in the Lancet reported that an elevated value of AFP in maternal serum was capable of identifying patients at risk of ONTD but, due to the large overlap with the normal population, was not diagnostic. · 1977: large scale collaborative study in the United Kingdom showed that AFP was useful as a screening test for ONTD. · 1979: first large scale collaborative study in the United States showed that screening with AFP between 15 and 21 weeks was capable of identifying up to 80% of cases of ONTD’s. What is AFP? · 1956: Bergstrand and Czar reported a protein detected in fetal serum as an extra band in the Alpha-1 region. Since it was not seen in normal adults it was called AFP · Related evolutionarily to albumin: · genes for both proteins are located in chromosome 4 · both have similar molecular weight (69,000 Daltons) · both have the same amount of negative charges. · Circulating time for AFP is 4 days · Anti-sera for AFP does not cross react with albumin therefore it can be used to detect it in maternal serum. AFP metabolism: · Synthesized in yolk sac and fetal liver · Peak fetal serum concentration is 300 mg reached during the end of the first trimester · The fetal liver produces AFP until 30 weeks of gestation and then stops rather abruptly. · A specific function for AFP has not been found. Fetuses with a genetic deficiency for production of AFP have been reported without adverse effects. Amniotic fluid AFP: · Appears mostly through fetal urine due to immaturity of fetal kidneys. Thus as kidneys mature, AF concentration gradually decreases. · It reaches a peak at 12 weeks & decreases 10% per week in the second trimester (see figure 1) · In cases of ONTD and any structural defect that affects skin permeability, it appears in the AF through transudation. · In cases of fetal congenital nephrosis, the large amount of proteinuria maintains AF concentrations high.