Karyotyping

Karyotypes—Human A karyotype is a photographic inventory of an individual’s chromosomes.

To study human chromosomes microscopically, researchers stain and display them as a karyotype. A karyotype usually shows 22 pairs of autosomes and one pair of sex chromosomes (#23). Karyotypes are used to determine chromosomal mutations that cause disabilities.

Normal Karyotype 46 chromosomes (23 pairs) Autosomes (body cells): 44 chromosomes (22 pairs) Sex chromosomes: 2 (1 pair) Sex chromosomes (one from each parent gamete): XY: Male XX: Female

Chromosomal Abnormalities Down Syndrome: “Trisomy 21” An extra 21st chromosome. Turner Syndrome: XO Female with only one X chromosome. Small stature and growth difficulties. Sterile. Triple X Females: XXX Females with longer legs and slender torsos. Klinefelter Syndrome: XXY, XXXY, or XXXXY Little facial hair, high-pitched voices, low testosterone. Sterile

Can you identify the chromosome abnormality in this karyotype? Is this individual a male or a female?

Normal, Female

Can you identify the chromosome abnormality in this karyotype? Is this individual a male or a female?

Female This individual carries three copies of chromosome 21. Down Syndrome. Symptoms include a variety of abnormalities including mental retardation, speckling of the irises of the eyes, poor muscle tone (hypotonia), characteristic appearance of the face, cardiac abnormalities, loose skin in the back of the neck, and fine, soft hair. Individuals with Down syndrome also are prone to leukemia, premature aging, and Alzheimer’s disease.

Can you identify the chromosome abnormality in this karyotype? Is this individual a male or a female?

Female Three copies of chromosome 13. Trisomy 13 syndrome or Patau syndrome. Babies with Trisomy 13 can have a variety of congenital abnormalities including incomplete development of the forebrain, olfactory and optic nerves, seizures, mental retardation, deafness, small head, sloping forehead, cleft lip and/or cleft palate, skin abnormalities, congenital heart defects, additional fingers and toes, prominence of the heels of the feet, thin or missing ribs, and other abnormalities.