Human genetics

Goals

1. To understand how the principles of genetics apply to our species

2. To understand how genetic abnomalities can cause deleterious health conditions

3. To understand how these conditions can be detected at various stages in the human life cycle

Outline:

Chromosomes

A. abnormalities in chromosome number (aneuploidy)

trisomy or monosomy

autosomal aneuploidies:

• Down syndrome (one form = trisomy 21)

  symptoms:

  aneuploidies of larger autosomes result in miscarriage

  monosomy is worse than trisomy

aneuploidies of sex-chromosomes:

• XO = Turner syndrome
• XXY = Klienfelter syndrome
• XYY = male (but with problems)
• XXX = female (trisomy X)

B. abnormalities in chromosome structure (translocation, deletion, duplication)

• one form of Down syndrome: translocation of part of 21 on 14

Genes

"inborn errors of metabolism" -- cannot make a protein correctly

they are generally recessive:

• phenylketonuria (PKU):
  • can't make an enzyme
  • symptoms:
  • treatment:
• sickle-cell anemia:
  • can't make a transport protein correctly (hemeglobin)
  • symptoms:
• cystic fibrosis:
  • can't make a membrane ion channel protein correctly
  • symptoms:

Huntington's disease is dominant (late onset)

hemophilia A is a recesive disease that is X-linked

• can't make a blood clotting factor
• symptoms:
• treatment:

Detection

carrier screening

• pedigree analysis
• incomplete dominance
• gene probes

  choices must be made about having children -- genetic counselling

pre-natal testing

• amniocentiesis
• chorionic villus sampling (CVS)

  choices must be made about the fetus -- genetic counselling

post-natal testing

symptoms of some genetic conditions can be avoided if detected early enough

• change environment/diet (PKU)
• supply missing protein (hemophilia A)
• drug treatment (cystic fibrosis)
• gene therapy (?)

Issues

who should know your genomic information?

a right to genetic privacy?

 

Vocabulary

click here to go to human genetics vocabulary