1. 11.1 GENETIC DISORDERS  BACKGROUND INFORMATION (Early 1900s) Sir Archibald Garrod, British physician, discovered patterns of inheritance leading to alkaptonuria— -Alkaptonuria disorder: urine turns black/acid excretion/severe arthritis  he NOTED: -ran in families, child could have it even if parents didn’t  recessive genetic disorder  he CONCLUDED: -dark urine inherited by biochemical abnormality  enzyme deficiency

2.  NEW VOCABULARY Heterozygous parents with recessive allele for disorder— ___________ carrier

3.  RECESSIVE GENETIC DISORDER RECESSIVE GENETIC DISORDERS— - individual is homozygous recessive--2 recessive alleles  disorder shown INFER: -What are the chances for 2 carriers to have a child with a recessive genetic disorder?__________ 25%

4.  PKU-Phenylketonuria *Identified at birth CAUSE: -Missing enzyme -- breaks down amino acid phenylalanine EFFECT/PREVELENCE: -excess phenylalanine -mental deterioration -1 in 10,000 TREATMENT: Lifelong diet that limits protein

5.  CYSTIC FIBROSIS *excessive mucus production CAUSE: -defective gene that codes for membrane protein EFFECT/PREVELENCE: -chloride ions not absorbed in cells -water does not diffuse from cells -digestive & respiratory failure -1 in 3,500 in US TREATMENT: -NO cure -pancreatic enzyme supplements -mucus thinning drugs -daily cleaning of mucus from lungs -physical therapy

6.  ALBINISM *lack of pigment/coloring in features CAUSE: -genes do not produce normal amounts of pigment--melanin EFFECT/PREVELENCE: -white hair -pale skin -pink pupils -TREATMENT: -NO cure -protect skin from sun -visual rehab

7.  ALBINISM www.positiveexposure.org

8.  ALBINISM www.positiveexposure.org

9.  ALBINISM www.positiveexposure.org

10.  GALACTOSEMIA CAUSE: -absence of gene -- codes for enzyme that breaks down galactose into lactose/glucose necessary for energy EFFECT/PREVELENCE: -mental disabilities -enlarged liver -kidney failure 1 in 50-70 thousand CURE: -NO cure -restricted diet of lactose/galactose -avoid milk products

11.  Tay-Sachs Disease/TSD *cherry red spot on back of eye CAUSE: -absence of necessary enzyme that breaks down fatty substances— gangliosides EFFECT/PREVELENCE: -affects people of Jewish descent -build up of fatty deposits in brain -mental disabilities -1/2500 CURE: -NO cure -death by age 5

12.  DOMINANT GENETIC DISORDER DOMINANT GENETIC DISORDERS— - individual is homozygous dominant -OR- heterozygous -disorder shown if a single dominant allele is present

13.  HUNTINGTONS DISEASE ?think about -symptoms do not show up until later in life CAUSE: -gene affecting neurological function is defective EFFECT/PREVELENCE: -decline of mental/neurological functions -ability to move deteriorates -uncontrollable movements -1 in 10,000 CURE: NO cure or treatment

14.  ACHONDROPLASIA *dwarfism CAUSE: -gene that affects bone growth is abnormal EFFECT/PREVELENCE: -short arms/legs -large head -1 in 25,000 CURE: -NO cure

15.  ACHONDROPLASIA

16.  DOMINANT GENETIC DISORDER IDENTIFY Which is more common—dominant or recessive disorders? -recessive

17.  GENETIC DISORDERS ANALYZE Why are recessive disorders more prevalent? -if dominant trait interferes with survival, individuals are less likely to pass the gene to the next generation -when disorder is recessive, carriers do not display disorder—pass on wo/being aware