Chromosomal Disorders

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Chromosomal Disorders
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Amniocentesis
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Single Chromosome Disorders

• Deletion
• Genetic material is missing
• 2. Duplication
• Genetic material is present twice
• 3. Inversion
• Genetic material is flipped

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Translocation (involves 2 chromosomes)

• Translocation
• Genetic material is added or swapped from another
  chromosome

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Chromosomal Non-disjunction

• when cells go through meiosis, the chromosomes
  dont separate correctly and either too many or
  not enough are passed on.

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What is Trisomy?

• Any extra chromosome
• Happens during non-disjunction!
• The non-disjunction rate increases with Moms age
• Incidence
• 1/750 live births.
• Mothers in their early twenties have a risk of
  1/1,500.
• Women over 35 have a risk factor of 1/70, which
  jumps to 1/25 for women 45 and over.

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An Example of Trisomy

• Downs Syndrome
• A.k.a- trisomy 21
• Shorthand
• 47, XY or XX, 21
• Survival rate is very high for this
  non-disjunction!

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Short stature, broad hands, stubby fingers and
toes, a wide rounded face, a large protruding
tongue that makes speech difficult. Individuals
with this syndrome have a high incidence of
respiratory infections, heart defects, and
leukemia.
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Edwards Syndrome

• This karyotype demonstrates trisomy 18
• Shorthand (47, XY, 18).

- Incidence is only 1 in 8000 live births.
- It is uncommon for fetuses with this condition
to survive
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Pataus Trisomy Syndrome
1 in 14,000 births 47 chromosomesXY or XX 13
Trisomy Nondisjunction
Small head Small or missing eyes Heart
defects Extra fingers Abnormal genitalia Mentally
retarded Cleft palate Most die a few weeks after
birth
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Klinefelter Syndrome
1 in 1,100 births 47 chromosomesXXY only 23
Trisomy Nondisjunction
Scarce beard Male anatomy Sterile Delicate
skin Low mental ability Normal lifespan
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Monosomy
Monosomy- having one fewer chromosome in each
body cell.
Generally, if a chromosomal mutations occurs
during meiosis, one half of the gametes will have
monosomy and the other half will have trisomy
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Turners Syndrome
1 in 5,000 births 45 chromosomes X only 23
MonosomyNondisjunction
96-98 do not survive to birth No menstruation No
breast development Narrow hips Broad shoulders
and neck
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Cri-Du-Chat Syndrome

• 1 in 216,000 births
• 46 chromosomes
• 5 Deletion of lower arm

Symptoms Moon-shaped face Heart disease Mentally
retarded Malformed larynx Normal lifespan