Topics in Genetics Flashcards
founder effect
when a few individuals migrate and found a new, isolated population, which is (by chance) different from the population that the settlers came from
heterozygote advantage
when having a recessive allele is advantageous, such as sickle cell resistance against malaria
genetic drift
a change in the frequency of a gene resulting from its transmission at higher or lower frequency than predicted
greatest impact on small populations
reproductive options available to couples at risk
prenatal diagnosis by amniocentesis or chorionic villus sampling
sperm or egg donation
preimplantation genetic diagnosis
adoption
choosing to accept the risk
bacterial inhibition assay
Dr. Robert Guthrie - test for PKU
agar plate spotted with blood samples, lack of inhibition leads to high phenylalanine levels
principles of newborn screening
important health problem
accepted treatement
facilities for diagnosis and treatment
recognizable latent or early symptomatic state
suitable test
test should be acceptable to population
natural history should be understood
agreed policy on whom to treat
cost should be economically balanced in relation to expenditure on medical care as a whole
case-finidng should be a continuing process
neurofibromatosis
autosomal dominant inheritance, 50% of cases result from new mutations in the gene
6 or more cafe-au-lait spots greater than 0.5cm or greater than 1.5cm for post puberty
axillary or inguinal freckling
2 or more neurofibromas or 1 plexiform NF
optic pathway tumor
2 or more iris Lisch nodules
distinctive osseous lesion
first degree relative with NF-1
NF-1 gene
very large gene, high mutation rate, more than 100 mutations found on NF-1
no common mutation or clear genotype-phenotype correlation
most mutations lead to decreased levels of gene product
acts as a tumor suppressor, at least in some tissues
down-regulates Ras oncogen, modulate cell growth and proliferation
