Quiz 2 Master List Flashcards
Xeroderma Pigmentosum
Cause: defect in nucleotide excision repair leads to the accumulation of thymine dimers
Symptoms: sensitive to direct sunlight, prone to developing melanomas and squamous cell carcinomas
Hereditary Nonpolyposis Colorectal Cancer
Cause: mutation in one of the genes for mismatch excision repair (either MSH2 or MLH1)
Cockayne Syndrome
Cause: defect in transcription coupled repair
Symptoms: neurological and developmental delay, photosensitivity, progeria (premature aging), hearing loss, and eye abnormalities; death usually occurs within the first 2 decades of life
BRCA-associated Breast Cancer
Cause: mutations in BRCA1 or BRCA2 (tumor suppressor genes) that cause a 5-fold increase in a woman’s risk in developing breast and/or ovarian cancer before menopause; men also have an increased risk for breast cancer, as well as pancreatic, testicular, and prostate cancer
Ataxia Telangiectasia (AT)
Cause: defect in the ATM protein, which is a protein kinase that is activated by double-stranded breaks and halts cell division
Familial Hypercholesterolemia
Cause: mutation in gene encoding the LDL receptor; receptors incapable of binding LDL OR bind LDL at reduced capacity OR bind LDL normally but are incapable of internalization
Symptoms: elevated LDL levels, which can lead to atherosclerotic plaques
Zellerger Spectrum Disorders
Cause: defects in the assembly of the peroxisome, most serious being an absence or reduced number of peroxisomes in the cells
Symptoms: present at patients at birth (congenital) and usually causes death within the first year of life
Autosomal Dominant Inheritance
Conditions exhibited in those with 1 copy of the mutant allele; affects males and females equally and any offspring have a 50-50 chance of inheriting the allele
Autosomal Recessive Inheritance
Conditions exhibited in those with 2 copies of the mutant allele; if just 1 is present, individual is a carrier but will not develop the condition; females and males affected equally; if 2 carriers mate, child will have 25% chance of being unaffected, 25% chance of being affected, and 50% chance of being an unaffected carrier
X-linked Dominant Inheritance
When mutation is in father’s X chromosome, all his daughters will express the condition with father-to-son transmission not possible; children of a carrier mother will have a 50% chance of inheriting the mutant allele, but subsequent condition is apparent only if the child has 2 copies of the mutant
X-linked Recessive Inheritance
Conditions not expressed in presence of a normal copy of gene; conditions always expressed in males because they only have 1 X chromosome, but women are rarely affected but can be if they have 2 copies of the mutant or random X-inactivation leaves a tissue vulnerable; never father-to-son transmission but may be father-to-daughter or mother-to-son/daughter transmission
Sickle Cell Anemia
Cause: missense mutation of 6th codon in allele for beta-globin (changes GAG to GTG) which changes glutamic acid to valine
Symptoms: cells have poor oxygen capacity, have sickle cell shape, and tend to clog capillaries, further restricting blood to tissues
Duchenne Muscular Dystrophy
Cause: out-of-frame (frameshift) deletion that results in little to no expression of dystrophin protein
Symptoms: muscle wasting, confined to wheel chair by 12 and death by respiratory failure within 10 years; symptoms onset typically by age 3-5
Becker Muscular Dystrophy
Cause: in-frame (frameshift) deletion that results in truncated forms of dystrophin and gives rise to a milder form of muscular dystrophy
I-Cell Disease
Cause: tagging of lysosomal proteins with mannose-6-phosphate is defective so proteins are not targeted to lysosomes
Symptoms: high plasma levels of lysosomal enzymes; by 6 months, FTT and developmental delays and physical manifestations; development delays of motor skills more pronounced than cognitive delays
Alzheimer’s Disease
Cause: amyloid protein (APP) breaks down to form amyloid beta peptide; misfolding/aggregation of A-beta forms plaques in the brain (extracellular) and hyperphosphorylation of Tau (intracellular)
Symptoms: loss of memory, cognitive function, and language