Nondisjunction disorders
-
Upload
caren-quinn -
Category
Documents
-
view
245 -
download
0
description
Transcript of Nondisjunction disorders
NondisjunctionNondisjunction Failure of sister chromatids or homologous
chromosomes to separate during Mitosis or Meiosis (metaphase 1 & 2)
This could result to a condition wherein the daughter cells have an abnormal number of chromosomes; one cell having too many chromosomes while other cell having none.
Trisomic- having three of one type of chromosome (1 extra) 2n+1
Monosomic- having a single chromosome instead of a pair (2n-1) (Turners)
Aneuploidy- is a condition in which the chromosome number is not an exact multiple of the haploid number of a particular species.
Autosomal chromosomes-Any chromosome except for the sex chromosomes. Humans have 44 autosomal chromosomes, or autosomes
Sex chromosomes- the 23rd pair of chromosomes determine the gender of the offspring
• Polyploidy-the condition in which a Polyploidy-the condition in which a normally diploid cell or organism acquires normally diploid cell or organism acquires one or more additional sets of one or more additional sets of chromosomes. Polyploidy is common chromosomes. Polyploidy is common among plants and has been, in fact, a among plants and has been, in fact, a major source of speciation in the major source of speciation in the angiospermsangiosperms
PlantProbable ancestral haploid number
Chromosomenumber Ploidy level
domestic oat 7 42 6n
peanut 10 40 4n
sugar cane 10 80 8n
banana 11 22, 33 2n, 3n
white potato 12 48 4n
tobacco 12 48 4ncotton 13 52 4napple 17 34, 51 2n, 3n
Human Human male male karyotypkaryotype, e, written written as as 46 46 XYXY
Human Human female female karyotypkaryotype, e, written written as as 46 46 XXXX
Jacob’s syndromeJacob’s syndrome
XYYNo abnormal
appearance/behaviorfertile
Jacob’s SyndromeJacob’s Syndrome1 in 1,800 births
47 chromosomesXYY only
47XYY
#23 Trisomy Nondisjunction
Jacob’s SyndromeJacob’s Syndrome
Normal physicallyNormal mentallyIncrease in testosteronePerhaps more aggressiveNormal lifespan
Klinefelter’s SyndromeKlinefelter’s Syndrome
XXY, male
Klinefelter’s SyndromeKlinefelter’s Syndrome1 in 1,100 births
47 chromosomesXXY only
47, XXY
#23 Trisomy Nondisjunction
Klinefelter’s Klinefelter’s SyndromeSyndrome
Scarce beardLonger fingers and armsSterileDelicate skinLow mental abilityNormal lifespan
Patau Patau syndromesyndrome
47, XX, +13
Patau’s Trisomy Patau’s Trisomy SyndromeSyndrome
1 in 14,000 births
47 chromosomesXY or XX
47, +13
#13 Trisomy Nondisjunction
Small headSmall or missing eyesHeart defectsExtra fingersAbnormal genitaliaMentally retardedCleft palateMost die a few weeks after birth
Patau’s Trisomy Patau’s Trisomy SyndromeSyndrome
Down SyndromeDown Syndrome47, XY, +21
1 in 1,250 births
47 chromosomesXY or XX
#21 Trisomy Nondisjunction
Down Syndrome
Down SyndromeDown Syndrome
Short, broad hands Stubby fingersRough skinImpotency in malesMentally retardedSmall round faceProtruding tongueShort lifespan
Edwards SyndromeEdwards Syndrome47, XY, +18
Edward’s Trisomy Edward’s Trisomy SyndromeSyndrome
1 in 4,400 births
47 chromosomesXX=80%
XY=20%
#18 Trisomy Nondisjunction
Edward’s Trisomy SyndromeEdward’s Trisomy Syndrome
Small headMentally retardedInternal organ abnormalities90% die before 5 months of age
Turners SyndromeTurners Syndrome
45, X
Turners SyndromeTurners Syndrome
96-98% do not survive to birthNo menstruationNo breast developmentNo hipsBroad shoulders and neck
Trisomy 16, monosomy XTrisomy 16, monosomy X
46, X, +16Not viable beyond 1st
trimester
Trisomy XTrisomy X47 XXX symptoms
1/1000healthy and fertile -
cannot be distinguished from normal female except by karyotype
Robertsonian Translocation Robertsonian Translocation 13-1413-14
Several types, with varying results.
Wolf Hirshhorn SyndromeWolf Hirshhorn Syndrome4p- Very rare. Affected children are small, with microcephaly
and abnormal facies. There are cardiac, renal, and genital abnormalities. Most are stillborn or die in infancy.
Cri-du-chat SyndromeCri-du-chat Syndrome
5p- site
Moon-shaped faceHeart diseaseMentally retardedMalformed larynxNormal lifespan
Aniridia-Wilms Tumor Aniridia-Wilms Tumor SyndromeSyndrome
1 in 50,000,000 births
46 chromosomesXY or XX
#11 Deletion of upper arm
Aniridia-Wilms Tumor SyndromeAniridia-Wilms Tumor Syndrome
Mentally retardedGrowth retardedBlindnessTumors on kidneysShort lifespan
Thirteen Q Deletion Thirteen Q Deletion SyndromeSyndrome
1 in 500,000 births
46 chromosomesXY or XX
#13 Deletion of lower arm
Thirteen Q Deletion SyndromeThirteen Q Deletion SyndromeMentally retardedDeformed faceNo thumbsHeart diseaseShort lifespan
Prader-Willi Prader-Willi SyndromeSyndrome
1 in 5,000,000 births
46 chromosomesXY=97% XX=3%
#15 Deletion of lower arm
Prader-Willi SyndromePrader-Willi Syndrome
Small bird-like headMentally retardedRespiratory problemsObesityShort lifespan
Eighteen Q Deletion Eighteen Q Deletion SyndromeSyndrome
1 in 10,000,000 births
46 chromosomesXY or XX
#18 Deletion of lower arm
Eighteen Q Deletion SyndromeEighteen Q Deletion SyndromeMentally retardedHeart diseaseAbnormal hands and feetLarge eyesLarge earsNormal lifespan
Cat-Eye SyndromeCat-Eye Syndrome1 in 1,000,000 births
46 chromosomesXY or XX
#22 Deletion of bottom arm
Cat-Eye SyndromeCat-Eye Syndrome
Fused fingers and toesMentally retardedSmall jawHeart problemsNormal lifespan
Four-Ring SyndromeFour-Ring Syndrome1 in 10,000,000 births
46 chromosomesXY or XX
#4 Inversion
Four-Ring SyndromeFour-Ring Syndrome
Cleft palateClub feetTestes don’t descendShort lifespan
Triple X SyndromeTriple X Syndrome1 in 2,500 births
47 chromosomesXXX only
#23 TrisomyNondisjunction
Triple X SyndromeTriple X Syndrome
Normally physically
Normal mentallyFertile