karyotypes

role of karyotypes

to detect chromosomal abnormalities within species, such as aneuploidy and polyploidy.

aneuploidy

when a cell or organism varies in the usual number of chromosomes in its genome by the addition or loss of a chromosome

polyploidy 

when an organism contains additional sets of chromosomes in its genome

names for varying forms of aneuploidy

• if an organism has one missing chromosome (2n-1), we call this monosomy.

• if an organism has one extra chromosome (2n+1), we call this trisomy.

• if an organism has two extra chromosomes (2n+2), we call this tetrasomy.

turner syndrome

monosomy

• Mutation: single X chromosome (often presented as XO)

• Incidence rate: 1 : 2 000

• Common symptoms: infertility, short stature, fused neck and head

down syndrome

TRISOMY

• Mutation: extra copy of chromosome 21

• Incidence rate: 1 : 1 000

• Common symptoms: delayed physical growth, possible heart defects, flattened facial profile, mild to moderate intellectual disability

Klinefelter syndrome

Trisomy

• Mutation: extra X chromosome in males (XXY)

• Incidence rate: 1 : 650 males born

• Common symptoms: accelerated growth and taller height, small testes and reduced testosterone levels, delayed or incomplete puberty, decreased muscle mass, learning and intellectual disabilities, infertility