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Flashcards in GiM week 8-10 Deck (86)
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what is another name for diGeorge syndrome?

and what chromosome is the microdeletion on?

velocardiofacial syndrome
(actually not identical but almost the same)

chromosome 22 (specifically: 22q11.2)


what is a pathological variant?

a genetic variant from the 'wild type' that CAUSES a disease in the phenotype


what is COMT and what is the association with alcoholism?


an enzyme, if you have a certain variant form of this enzyme (caused by genetic variation) then it increases the likelihood, if you are a social drinker, of becoming an alcoholic


what two types of mutations will microarray analysis NOT detect?

- balanced translocations
- mosaicism (depends)

this is because microarrays measure gene dosage, which doesn't change with balanced translocations and doesn't change universally with mosaicism


what does FISH stand for?

fluorescence in situ hybridisation


what are the functions of T-Box genes?

encode transcription factors involved in the regulation of developmental processes


what is blepharophimosis?

narrowing of the eye opening


what is sclerocornea?

clouding of the cornea to a varying degree


what are the 5 major medicalproblems associated with DiGeorge?

- heart defects
- poor immune system control
- cleft palate
- complications related tolow blood calcium
- delayed development (w. behavioral + emotional problems)


what % of breast cancers are caused my inherited mutations of brca1 + brca2 genes?



what is retinitis pigmentosa?

a collection of genetic mutations which causes inherited late-onset blindness (via retinal degeneration)

- loose peripheral vision and night vision first, so get tunnel vision, then go completely blind


what does fully penetrant mean?

if you have the mutated gene then you definitely WILL have/get the condition! - eg huntingtons


describe treacher-collins syndrome

craniofacial deformities
- including eyes (downward slanting), ears and cheekbones

- normal intelligence


what are the two main invasive methods of prenatal testing used? and at what gestation are they used?

chorionic villus sampling
- about 11 weeks
- more common

- about 17 weeks


what is preimplantation non-disclosure testing? for huntingtons

eg Want to make sure embryo does not have mutation even if don’t know mothers risk, so test genes and make sure no genes from grandmother (who is infected)


what is the difference in obesity trends in monozygotic and dizygotic twins?

Twins separated at birth
Dizygotic twins have variety in BMI
Monozygotic twins have very similar bmi


what is leptin?

what hormone opposes its actions?

the 'satiety hormone'

made by adipose cells, inhibits hunger

opposed by ghrelin (the 'hunger hormone')


what happens in leptin deficiency?

the mouse/person lacks the 'ob' gene, which codes for leptin

so you never feel full --> get very fat

nb you can also have mice/people who lack a gene which codes for the leptin receptor, so the adipose cells are producing leptin but the brain is not receiving that signal


what is Leber's congenital amaurosis (LCA)?

- Rare inherited eye disorder (autosomal recessive)

- blindness at birth/early infancy

- over 22 genes implicated


what are the 2 reasons that the eye is a good place to use gene therapy?

- immune privileged

- easily accessible, via subretinal injection


what gene is targeted for gene therapy of LCA?



what is pharmacogenetics?

correlation between the effects of drugs and the genetic constitution of patients


what are cytochrome P450 oxidases?

give an example of one?

Multigene family of enzymes found predominantly in the liver

Responsible for the metabolic elimination of most drugs currently used

Also important for converting pro-drugs to their active forms (eg codeine)

example: CYP2D6


what effect does CYP2D6 have on tamoxifen metabolism?

CYP2D6 converts tamoxifen to its active metabolite: endoxifen

people with reduced CYP2D6 function are thus poor metabolisers of tamoxifen --> worse survival (when being treated w. tamoxifen for breast cancer)


what does androgenesis mean?

male reproduces without female partner

"ANDROgens are typically MALE sex hormones, such as testosterone"


what does parthenogenesis mean?

female reproduces without male partner


in normal, sexual, fertilisation when does the sperm fertilise the egg?

at the same time as the second meiotic division (expulsion of 2nd polar body)


what causes a hydatidiform mole (aka molar pregnancy)? and what is it?

androgenetic conception

(no female genetic tissue, 2 sets of male genetic tissue)

proliferation of abnormal trophoblast tissue (no remaining embryo)

produces a positive preganancy test


what causes benign ovarian teratomas and what are they?

(lots of eggs, no sperm)

wide spectrum of tissues,predominately epithelial (fat, hair, teeth) - no skeletal muscle

no membranes/placenta


why do parthenogenetic embryos die?

due to failure of development extraembryonic structures:
- yolk sac
- trophoblast