Genetics Flashcards
mendelian inheritance and genetic disease, genetic testing (cytogenetics) and multifactorial disorders individuality and personalized medicine
Autosomal Recessive Inheritance chances if both parents Aa
If parents are both carriers of the mutations in the same recessive gene, each pregnancy has :
- 25% chance of inheriting both normal genes
- 50% chance of being a carrier
- 25% chance of inheriting both gene mutations and being affected
= 75 % CHANCES NOT BEING AFFECTED, AND 25% YES
What’s PKU
It is a gene. Mechanism of action: the PAH isn’t working - a disease where phenylalanine can’t be digested (because it can’t be transform to tyrosine since the PAH isn’t working)
allelic heterogeneity
when you have a vast number of different mutation in the same gene that leads to a particular condition
locus heterogeneity
when one disorder is caused by more than 1 gene
Autosomal Dominant Inheritance chances if both parents Aa
Each offsprings of an affected parent has a 75% chance of being affected and a 25% chance of being unaffected
Marfan syndrome
autosomal dominant inheritance - arachnodactyly, lens dislocation, dilation of aorta, arm span that exceeds her height
Pleiotropy
defects in one gene cause multiple clinical manifestations (one gene influences 2 or more seemingly unrelated phenotypic traits)
penetrance
(yes or no). The patient either have the disease or not. Full penetrance = everyone who has the mutation will express the disease in one way or another
expressivity
how a person is affected, what are the symptoms that may differ from one individual from another (like a dimmer switch)
Can the condition of X linked inheritance be transmitted from father to son ?
No, cause he passes his Y chromo
What are the chances of a son being affected if the mother is a carrier in X-linked inheritance ?
Sons of carrier females have a 50% chance of being AFFECTED and a 50% chance of being UNAFFECTED with each pregnancy
What are the chances of a daughter being affected if the mother is a carrier in X-linked inheritance ?
Daughters of carrier females have a 50% chance of being A CARRIER and a 50% chance of being UNAFFECTED with each pregnancy
duchenne muscular dystrophy
- X-linked inheritance
- gowers signs (standing from sitting is difficult)
- caused by a mutation in the DMD gene, one of the largest genes (1/3 mutations occur de novo)
characteristic of Y-linked inheritance ?
never occur in female, and always in males
what is the threshold effect for clinical expression of multifactorial disorders ?
combination of multiple genes (polygenic) and environmental (lifestyle) factors
if one child or parent has a multifactorial disorder, what’s the recurrence risks for the next child ?
5-10%
if more than one child or parent has a multifactorial disorder, what’s the recurrence risks for the next child ?
10-15%
SNPs
- single nucleotide polymorphisms
- an individual’s response to a drug is often linked to these common DNA variations
CNVs
- copy number variants
- disease risk factors in complex disorders (autism)
- change in the number or arrangement of genes
advantages of personalized medicine
- better informed clinical decision
- higher probability of improved health outcomes
- lower probability of adverse reactions from medication
- focus on prevention and prediction of disease
- reduced healthcare costs
most common epigenetics mechanism ?
- methylation of DNA
- modifications of histone proteins
- noncoding RNAs
pharmacogenomics
the study of genetic differences in metabolic pathways that affect individual responses to drugs (high or poor metabolizer)
