Karyotypes and Complications Flashcards
What are karyotypes?
Organized profiles of a person’s homologous chromosomes (somatic cells only)
Karyotypes are used to assess chromosomal abnormalities and genetic disorders.
How are chromosomes organized in a karyotype?
By size, banding patterns, and location of centromere
This organization helps in identifying chromosomal abnormalities.
What determines sex in human karyotypes?
Chromosome Pair #23
This pair may not match up, as it can consist of two X chromosomes (female) or one X and one Y chromosome (male).
What are the types of chromosomes in a human karyotype?
- Sex chromosomes
- Autosomes or autosomal chromosomes
Humans have 22 pairs of autosomes and 1 pair of sex chromosomes.
What are autosomal disorders?
Disorders that involve the 22 pairs of chromosomes
These can result from an extra chromosome or defective genes.
What is nondisjunction?
Failure of homologous chromosomes or sister chromatids to separate properly during cell division
This can occur during meiosis I or meiosis II.
What happens during nondisjunction in Meiosis I?
Failure to separate homologous pairs
This can lead to an abnormal number of chromosomes.
What happens during nondisjunction in Meiosis II?
Failure to separate chromatids
This can also result in an abnormal number of chromosomes.
What does monosomy mean?
The presence of only 1 homologous chromosome
This results in 45 chromosomes, and embryos with this condition typically do not survive.
What does trisomy mean?
The presence of 3 homologous chromosomes
This results in 47 chromosomes and can lead to various syndromes.
What is Down Syndrome?
A genetic disorder characterized by abnormal facial features, developmental delays, and occurs in 1 in 700 live births
It is caused by trisomy 21.
What are symptoms of Trisomy 13?
- Cleft lip or palate
- Close-set eyes
- Decreased muscle tone
- Extra fingers or toes
- Hernias
- Hole, split, or cleft in the iris
- Low-set ears
- Intellectual disability
Trisomy 13 is also known as Patau Syndrome.
What characterizes Klinefelter’s Syndrome?
XXY sex chromosomes, infertility, and tall stature with breast development
It occurs in 1 in 800 live births.
What is Turner Syndrome?
Characterized by a single X chromosome, infertility, and partially developed secondary sexual features
It occurs in 1 in 10,000 live births.
What is XYY Syndrome?
Characterized by an extra copy of the Y chromosome, typically causing no unusual physical features
Males with this condition may be taller than average and have normal sexual development.
What is amniocentesis?
A prenatal testing procedure where cells are taken from amniotic fluid to create a karyotype
This can be done between 11-14 weeks of pregnancy.
What is chorionic villus sampling (CVS)?
A prenatal testing procedure where cells are taken from the chorion to create a karyotype
This can be performed as early as 8 weeks of pregnancy.
