Bio- Human Genetics: Disorders

Autosomal Disorders

• autosome- non sex chromosomes, 1-22

• recessive

  • case study

  • projects

• Dominant

  • Huntington’s- makes too many Huntington proteins

  • Woody Guthrie

Sex Linked Disorders

• any gene on X or Y

• Y is very small

• disorders are usually on X

• recessive X linked are most often expressed in males

• Ex: Colorblindness

  • groups of cones in the retina have pigments that are sensitive to specific wavelengths

  • some pigments don’t get made

• Ex: Hemophilia- “Royal Disease”

  • inability to form protein for blood to clot

Sex Influenced Traits

• gene is on an autosome

• expression influenced by gender

• Ex: Male pattern baldness

  • not completely bald

  • can be in arc pattern, random in females

  • BB- normal, doesn’t matter the gender

  • bb- bald, M- pattern and F- random

  • Bb- Males are bald, Females are normal

Nondisjunction Disorders

• homologous chromosomes or chromatids don’t separate properly

• produces gametes with either too many or too few

• resulting offspring will have an incorrect number of chromosomes

• Turner Syndrome

  • has single X chromosome

  • female but reproductive system does not develop

• Klinefelter syndrome

  • XXY

  • male, sterile

• Down Syndrome

  • Trisomy 21- have 3 copies of chromosome 21

  • can be male or female

  • physically and intellectually challenged

  • can range from moderate to severe

Diagnosis

• karyotype- pic of chromosomes

• Amniocentesis

  • small amount of amniotic fluid is removed and cells are grown in a lab

  • cells are karyotyped

  • presents slight risks to mother and fetus

  • takes a while for them to grow

• Chorionic villus biopsy

  • portion of the membrane surrounding embryo is removed and grown

  • karyotyped

  • faster, more risky

• Pedigree analysis

  • shade in half of shape to show carrier