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

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