Human Chromosome Disorders

Karyotype—Map of Human Chromosomes

Homologue

Homologue

Chromosome disorders

• Sometimes meiosis goes wrong

• Most of the time, the pregnancy ends naturally because most chromosome disorders are lethal

• Extra chromosome = trisomy

21 trisomy – Downs 21 trisomy – Downs SyndromeSyndrome

Can you see the extra 21st chromosome?

Is this person male or female?

Down’s syndrome*A flattened appearance to the face

*An upward slant to the eyes

* Short neck, arms and legs

*Intellectual disability

*Extra friendly and outgoing

Edward’s syndrome-trisomy 18

• Clenched hands• Crossed legs • Feet with a

rounded bottom (rocker-bottom feet)

• Mental deficiency

• Small head

Patau syndrome

Trisomy 13

Turner’s syndrome—the only case of missing a chromosome that can be survived

• Females who are XO instead of XX

• Stocky appearance, arms that turn out slightly at the elbow, a receding lower jaw, a short webbed neck.

• Other medical symptoms include: heart and/or kidney defects, high blood pressure, and infertility (inability to have children).

What if a karyotype showed you would have a child with a chromosomal abnormality?

What would you do?