Factors of Birth Defects

• Genetically based, malformations can be caused by :

  (1) Abnormalities of chromosomal division (2) Mutations of genes
• Chromosomal abnormalities are usually classified as ___ & ___?

  Structural or Numerical Errors
• When do chromosomal abnormalities arise?

  During CELL DIVISION, MEIOSIS via NONDISJUNCTION
• It is the failure of chromosomes to separate properly during the process of cell division. This can result in an uneven distribution of chromosomes into the daughter cells.


  Nondisjunction
• It is defined as a total number of chromosomes other than the normal 46.

  Aneuploidy
• Type of Aneuploidy which an organism is MISSING ONE COPY of a particular chromosome, resulting in a TOTAL CHROMOSOME that is ONE LESS than the typical DIPLOID number.


  Monosomy
• Example of Monosomy where females are born with only one X chromosome instead of the typical two. This is not TYPICALLY INHERITED and often occurs SPORADICALLY through NONDISJUNCTION


  Turner Syndrome (45, X)
• It causes the loss of one X chromosome in the formation of either the egg or the sperm.


  Nondisjunction
• Having Turner Syndrome will lead to?

  Short Stature, Webbed Neck, and Infertility
• It is the specific chromosomal makeup.


  Karyotype
• It is a type of Aneuploidy wherein an organism has an ADDITIONAL COPY of a particular chromosome resulting in a total chromosome count that is ONE MORE than the typical DIPLOID number.


  Trisomy
• It is the other term for Down Syndrome.


  Trisomy 21
• Individuals with three copies of chromosome 21 instead of the USUAL two (47, XY +21 / 47, XX + 21)

  Down Syndrome
• What happens in Down Syndrome cases?

  95 % of the cases result from NONDISJUNCTION during the FORMATION of the EGG/SPERM, and this error leads to an extra chromosome 21 in the resulting embryo.
• What is the result of this EXTRA GENETIC MATERIAL to the individual with Down Syndrome?


  Characteristic Physical Features and Intellectual Disabilities