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Non-Disjunction Disorders. What are Non-Disjunction Disorders?!What are Non-Disjunction Disorders?!  Non-disjunction is a failure of chromosomes to separate.

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Presentation on theme: "Non-Disjunction Disorders. What are Non-Disjunction Disorders?!What are Non-Disjunction Disorders?!  Non-disjunction is a failure of chromosomes to separate."— Presentation transcript:

1 Non-Disjunction Disorders

2 What are Non-Disjunction Disorders?!What are Non-Disjunction Disorders?!  Non-disjunction is a failure of chromosomes to separate properly (i.e there is an imbalance of genetic information)  Occurs when:  Homologous chromosomes fail to separate properly in Anaphase I  Sister chromatids fail to separate properly during Anaphase II  Having abnormal amounts of karyotypes will overload the cells, which may result in:  The death of the zygote  A person with a non-disjunction disorder being born

3 Key TermsKey Terms  Karyotypes  The number and visual appearance of the chromosomes in the cell nuclei of an organism or species  Trisomy  A condition in which a diploid organism has one more chromosome than usual.  47  Monosomy  An instance where there is only one chromosome is present, as opposed to the usual two

4 Human male karyotype, written as 46 XY

5 Human female karyotype, written as 46 XX

6 Autosomal Non-DisjunctionAutosomal Non-Disjunction  Refers to chromosome alterations in autosomes one through twenty-two (1 - 22)  There only 3 trisomies (13, 18, & 21) that result in a baby that can survive for a time after birth  The other trisomies are so devastating that the baby usually dies in utero

7 WARNING!  SOME OF THE PICTURES IN THE FOLLOWING SLIDES MAY BE UPSETTING/TOO GRAPHIC FOR SOME STUDENTS!  IF YOU FEEL THE NEED TO, PLEASE LOOK AWAY FROM THE SCREEN

8 Patau syndrome  47, XX, +13

9 Patau’s Trisomy SyndromePatau’s Trisomy Syndrome 1 in 14,000 births 47 chromosomes XY or XX 47, +13 #13 Trisomy Nondisjunction

10 Small head Small or missing eyes Heart defects Extra fingers Abnormal genitalia Mentally retarded Cleft palate Most die a few weeks after birth Patau’s Trisomy SyndromePatau’s Trisomy Syndrome

11 Edwards SyndromeEdwards Syndrome  47, XY, , XY, +18

12 Edward’s Trisomy SyndromeEdward’s Trisomy Syndrome 1 in 4,400 births 47 chromosomes XX=80% XY=20% #18 Trisomy Nondisjunction

13 Edward’s Trisomy SyndromeEdward’s Trisomy Syndrome Small head Mentally retarded Internal organ abnormalities 90% die before 5 months of age

14 Down SyndromeDown Syndrome  47, XY, +21

15 1 in 1,250 births 47 chromosomes XY or XX #21 Trisomy Nondisjunction Down Syndrome

16 Down SyndromeDown Syndrome Short, broad hands Stubby fingers Rough skin Impotency in males Mentally retarded Small round face Protruding tongue Short lifespan

17 Non-Disjunction in Sex ChromosomesNon-Disjunction in Sex Chromosomes  Issues arise in homologous pair 23 (X or Y)  Can be fatal  Although many people have these karyotypes and are alive and well.

18 Jacob’s syndromeJacob’s syndrome  XYY  No abnormal appearance/behavior  fertile

19 Jacob’s SyndromeJacob’s Syndrome 1 in 1,800 births 47 chromosomes XYY only 47XYY #23 Trisomy Nondisjunction

20 Jacob’s SyndromeJacob’s Syndrome Normal physically Normal mentally (average IQ) May have learning disabilities Increase in testosterone Perhaps more aggressive Normal lifespan

21 Klinefelter’s SyndromeKlinefelter’s Syndrome  XXY  Found in males

22 Klinefelter’s SyndromeKlinefelter’s Syndrome 1 in 1,100 births 47 chromosomes XXY only 47, XXY #23 Trisomy Nondisjunction

23 Klinefelter’s Syndrome Klinefelter’s Syndrome Scarce beard Longer fingers and arms Sterile Delicate skin Low mental ability Normal lifespan Lower than average testosterone production

24 Turners SyndromeTurners Syndrome  45, X 45, X  The only viable monosomy in humans

25 Turners SyndromeTurners Syndrome 96-98% do not survive to birth No menstruation No breast development No hips Broad shoulders and neck

26 Trisomy 16, monosomy XTrisomy 16, monosomy X  46, X,  Not viable beyond 1 st trimester

27 Trisomy XTrisomy X  47 XXX symptoms 47 XXX symptoms  1/1000  healthy and fertile - cannot be distinguished from normal female except by karyotype

28 Triple X SyndromeTriple X Syndrome 1 in 2,500 births 47 chromosomes XXX only #23 Trisomy Nondisjunction

29 Triple X SyndromeTriple X Syndrome Normally physically Normal mentally Fertile

30 Cri-du-chat SyndromeCri-du-chat Syndrome  5p- site 5p-site Moon-shaped face Heart disease Mentally retarded Malformed larynx (have a cat like cry) Normal lifespan


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