DNA Mutations Flashcards
What is Hemochromatosis?
Too much iron in the body. It is also called iron overload.
What factors partly explain why males are almost twice as likely to present with symptomatic disease as females?
Environmental factors: Menstruation, pregnancy, frequent blood donation, diet, alcohol, other diseases (such as hepatitis)
What are the symptoms of hereditary hemochromatosis?
-excess iron is deposited in the liver, pancreas, heart, joints, and endocrine glands
-Symptoms: hyperpigmentation, enlarged liver, impotence, testicular atrophy, joint swelling, tenderness, and fatigue
When are symptoms of hereditary hemochromatosis detected in patients?
Age between 30-60, later in females
the most common inherited liver disease in Caucasians
Which gene is involved in hereditary hemochromatosis?
HFE gene -> the HFE membrane protein regulates iron absorption
How is the HFE membrane protein believed to regulate iron intake?
Regulating the interaction between the transferrin receptors and transferrin
What mutations occur in hereditary hemochromatosis and what are the consequences?
-Histidine (+) to Aspartate (-): changes charge of the molecule
-Cysteine to Tyrosine: changes the shape of the molecule
Cysteine forms disulfide bonds -> facilitates tertiary structure and correct folding
What is a heterozygote compund?
an organism that contains two copies of a gene, each copy having a different recessive mutation that together can confer the null (or disease) phenotype. -> Aa or aA
What is the penetrance of a phenotype?
It refers to the percent of individuals with a particular genotype
who also exhibit the associated phenotype
Explain the incomplete penetrance in hereditary hemochromatosis:
not all individuals who are homozygous for one of the two mutations (or compound heterozygotes) will actually develop disease symptoms.
Are all exons in the coding sequence part of the final protein?
No, some are part of signal sequences, or regulatory sequences
