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18 Cards in this Set
- Front
- Back
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What exogenous causes are there for congential defects? |
Teratogens i) drugs and chemicals ii) ionizing radiation iii) high temperature iv) infectious microorganisms v) mothers metabolisc conditions |
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When is the embryo most susceptible to teratogens? |
3-8 weeks when most organ structures form |
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What is one of the most devastating teratogens? What does it cause? |
Alcohol Causes fetal alcohol syndrome |
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In mice what causes FAS? |
Failure of anterior neural tube to close |
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What causes the brain effects of FAS? |
As a result of increased cell death and weakened cell adhesion due to inhibition of the L1 binding. |
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What is the classical teratogen? |
Thalidomide - caused limb defets |
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What are the types of congenital limb defects? |
1. Reduction defects 2. Duplication defects - polydacyly 3. Dysplasia - malformation / excessive limb growth |
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What diseases result from mutations in FGF receptors? What is this disease type sometimes termed? |
1. Alpert syndrome, Pfeiffer syndrome & dwarfism 2. Sometimes termed 'gain of function' mutations resulting in receptor hypersensitivity - where the receptors respond to additonal ligands |
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What is the gene which causes FGF receptor conditions? |
FGFR2 |
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What intrinsic genetic events cause genetic diseases? |
1. Point mutations - e.g PAX6 2. Aneuplodies - Trisomy21 3. Chromosomal translocations - SrY gene |
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What is a very unusual chromosomal translocation. What does it result in? |
SrY gene translocated to an X chromosome during male meiosis causes sex reversal: XX males XY females |
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What are neural tube defects? |
Genetic diseases resulting from a failure of even 1 part of the rube to close which disrupts the differentiation of the CNS |
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How can we identify the genetic causes of birth defects? |
1. Positional gene cloning 2. Confirming the function of a candidate gene 3. Candidate gene mapping |
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When was confirming the function of a candidate gene a successful strategy? |
PAX6 - candidate gene KOed in mice which results in a small eye which is analogous to the 'Anridia' human disease which is also caused by PAX6 |
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How was candidate gene mapping used to confirm the basis of Waardenburg syndrome type II? |
In mice the disease 'small eye' is caused by MitF gene abnormalities and shares the phenotype with human waardenburg syndrome II. The human equivalent of MitF was found, mapped and became a candidate gene this was later researched and confirmed. |
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What gene & strategy was used to find the basis for piebaldism? |
Mouse KO 'KIT' shared many similar phenotypes. |
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What is heterogenity and what 2 diseases are genetically heterogenous? What is the cause of this? |
Where defects in different genes cause similar phenotypes - Piebaldism and Waardenburg syndrome type II Both gene products work on the same pathway. 1. KIT receptor - piebaldism 2. MitF interacts with KIT receptor. Both required to have the effect. |
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In what ways are mice being used to find new therapeutics for: 1. ALS / motor neuron disease 2. Marfan syndrome ? |
1. Investigate of MiR-206 which downtregulates HDAC4 - leading to production of a growth factor which stimulates renervation 2. Fibrillin-1 mutation = connective tissue defect which upregulates TGF beta pathway - Losartan inhibits the pathway |
