Genetic Disorders

Tay Sachs Disease of the nervous system Life expectancy: <5 years Autosomal recessive Gene on chromosome 15

Autosomal Chromosomes SEX

Tay Sachs NN = Normal Nn = Carrier nn = affected

Tay Sachs How can this disease continue to exist if all victims die before reproducing?

Tay Sachs N n N NN Nn n Nn nn

3 chromosomes of the 21st pair. Down Syndrome 3 chromosomes of the 21st pair. aka: Trisomy 21

Mom’s chromosomes Dad’s chromosomes Non-disjunction Proper Segregation

Down Syndrome Extra 21st chromosome Non-disjunction 1 in 700 live births

Cystic Fibrosis Thick mucous-clogged lungs Constant coughing Autosomal recessive (Not carried X or Y)

How many chromosomes are autosomal? 44

Cystic Fibrosis NN = Normal Nn = Carrier nn = affected

Huntington's Nerves/muscles break down Brain function/psychiatric problems Autosomal Dominant (not on X or Y)

Huntington's HH = Affected Hh = Affected hh = Normal

Sickle-Cell Autosomal Recessive Life expectancy: ~ 50 years

Sickle-Cell Sickle-Celled blood cells are resistant to malaria Malaria: a mosquito-bourne disease Sickle-Cell has been naturally selected for its resistance to malaria, therefore more common in tropic areas.

Kleinfelter’s XXY Nondisjucntion Normal

Kleinfelter’s XXY 47 XXY – 1 in 500 births 48 XXYY – 1 in 18k to 50k births 49 XXXXY – 1 in 100k births Just as healthy as normal children, but infertile

Kleinfelter’s XXY

Turner’s Syndrome (45X) Missing an X chromosome 1 in 5000 live births 98% die before birth Short stature Swelling of the hands and feet Low hairline Low-set ears Reproductive sterility Increased weight, obesity Shortened metacarpal IV, small fingernails Webbed neck Visual impairments, ear infections and hearing loss

Common Genetic Disorders Tay Sachs (autosomal recessive) Down Syndrome (21st pair) Cystic Fibrosis (autosomal recessive) Huntington’s (autosomal dominant) Sickle-Cell (autosomal recessive) Kleinfelter’s (23rd pair) Turner’s Syndrome (23rd pair)