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Non-Disjunction Disorders

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Presentation on theme: "Non-Disjunction Disorders"— Presentation transcript:

1 Non-Disjunction Disorders

2 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 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-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


8 Patau syndrome 47, XX, +13

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

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

11 Edwards Syndrome 47, XY, +18

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

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

14 Down Syndrome 47, XY, +21

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

16 Down 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 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 No abnormal appearance/behavior fertile
Jacob’s syndrome XYY No abnormal appearance/behavior fertile

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

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

21 Klinefelter’s Syndrome
XXY Found in males

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

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

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

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

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

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

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

29 Triple X Syndrome Normally physically Normal mentally Fertile

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

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