Chapter 5 Flashcards
Traits of Mendelian Disorders (4)
- Highly Penetrant
- Single gene mutations
- Follow mendelian inheritance
- Generally rare unless there is strong selection (sickle cell)
traits of Chromosomal Disorders (2)
- Structure or number problems
2. Highly penetrant
traits of Complex Multigene disorders (3)
- AKA polymorphisms (each mutation add a little to problem)
- More common
- Low penetrance/highly variable
Point Mutations (1)
- Single BP switch
Types of point mutations? (2)
- Missense (conservative and non-conservative)
2. Nonsense mutations
This mutation forms a stop codon.
Nonsense mutation
This mutation changes one Amino Acid
Missense
B-thalassemia is what type of mutation?
Nonsense mutation
anemia due to reduced b-globulin?
Example of non-conservative missense, deals with blood cell shape.
Sickle cell
Intron related mutations are in …?
non-coding sequences
Effects of mutations in non-coding sequences? (2)
- Transcription problems (effect regulatory sequences
2. mRNA processing and splicing issues
2 outcomes of deletions/insertions?
- Frame shift (often premature stop codon arises)
2. Multiple of 3 (add/subtract AA)
Tay-sachs is an example of what type of insertions?
4 BP insertion
Trinucleotide-repeat mutation traits (2)
- Amplification of 3 NT sequences (mostly GC)
2. Non-classic inheritance pattern (increases with generations) aka dynamic
Pleotropism
1 genes => many effects (sickle cell)
Genetic Heterogeneity
Multigens => 1 effect
Autosomal Dominant Disorders characteristics (2 to really know)
- Patients w/o effected parents = new mutation
2. Penetrance can vary
Autosomal Recessive Disorders (2)
- Early onset relative to dominant disorders
2. Complete Penetrance
X-Linked Disorders
- Most are recessive
- Males are affected and pass to daughter carriers (no sons)
- Daughter carriers pass to sons
Biochemical and Molecular basis of single Gene - 4 mechanisms
- Enzyme defects and consequences
- (metabolic block, Lack of feedback, failure to inactivate tissue damaging substrate) - Defects in R + transport systems (ex. Familial hypercholesterolemia)
- Alterations in structure, Function or quality of nonenzyme proteins
- Genetically Determined Adverse Reactions to drugs.
Marfan Syndrome: Defect in?
Fibrillin
Where is Fibrillin found? (3)
Marfan Syndrome:
1. Eyes
- Skeleton
- Cardiovascular system
Marfan Syndrome: Fibrillin mutation?
FBN1 (can be FBN2)
Fibrillin scaffolding for?
Elastin
Marfan Syndrome: What else plays a factor (not fibrillin).
Excessive TGF-B activation
Excessive TGF-B activation leads to?
- bone overgrowth
2. Myxoid changes in MITRAL VALVES
What causes TGF-B problems?
Reduced microfibril activation (normal microfibrils cage TGF-B)
Marfan Syndrome: Morphologic changes
- Skeletal abnormalities
- Ocular changes
- Cardiovascular
Marfan Syndrome: Skeletal abnormalities
- Tall, long limbs, tapering fingers and toes
- Joints are lax, tongue can be hyperextended to wrist
- dolichocephalic (longheaded)
- Spinal deformities
Marfan Syndrome: Ocular Changes
- Bilateral luxation or dislocation (up or out)
- Ectopia lentis bilaterally
Marfan Syndrome: Cardiovascular changes
- Mitral Valve prolapse
- Dilation of ascending Aorta
- diagnosed via echocardiograph
Marfan Syndrome: Diagnosis
2/4 organ systems
Marfan Syndrome: Treatment
B-blockers: angiotensin 2 blockers in humans
Ehlers-Donlos Syndromes (EDS): main problem?
Collagen
-Post transcriptional
Tissues rich in collagen?
- Skin
- Ligaments
- Joints
Ehlers-Donlos Syndromes (EDS): Clinical presentation
- Extreme Flexibility
- Minor injuries => gaping
- Rupture of colon or Large A.
- Ocular fragility and retinal detachment
- Diaphragmatic Hernia
Ehlers-Donlos Syndromes (EDS): Types?
- Kyphoscoliosis (most common-Type 6)
- Vascular EDS (Type 4 EDS and type 3 collagen)
- Arthrochalasia and dermatosparaxis (type 7 EDS and Type 1 collagen-procollagen to collagen)
- Classic type (type 1/2 and Type 5 collagen)
Ehlers-Donlos Syndromes (EDS): Recessive or Dominant?
Recessive
Ehlers-Donlos Syndromes (EDS): Kyphoscoliosis mutation?
Lysyl Hydroxylase
LDL receptor mutation is seen in?
Familial Hypercholesteralemia
Familial Hypercholesteralemia: What are the 3 proteins on VLDL
- ApoC
- B-100
- ApoE
Familial Hypercholesteralemia: What protein remains on IDL
- ApoE
2. B-100
Familial Hypercholesteralemia: What protein remains on LDL
- B-100
VLDL and IDL contain
Cholesterol and Triglycerides
-IDL has less triglycerides
LDL contains
Just cholesterol
Familial Hypercholesteralemia: 5 classes
class 1: synthesis class 2: transport class 3: binding Class 4: Clustering Class 5: Recycling
Percent of IDL to liver?
50%
What does LDL receptor recognize?
ApoE and B-100
Synthesis of cholesterol requires what enzyme?
HMG CoA reductase
NPC does what?
Removes cholesterol from lysosome.
NPC is related to what disease?
Nieman-Pick Disease
What stimulates storage of cholesterol esters?
acyl-coenzyme A
and oversupply of cholesterol
Familial Hypercholesteralemia: Results in? (5)
- decreased LDL catabolism
- increased Plasma LDL (2x or 5x)
- Increased LDL synth
- Impaired IDL transport => increased LDL formation
- Scavangers/monocytes can’t handle load => Xanthomas
Familial Hypercholesteralemia: is what type of disease?
Autosomal Dominant
Polygenic: requires multiple polymorphisms
Familial Hypercholesteralemia: Treatment?
Statins (2ndary prevention of ischemic heart disease)
Lysosomal storage diseases: (5)
- Tay-sachs
- Nieman-Pick Type A and B
- Nieman-Pick Type C
- Gaucher Disease
- Mucopolysaccharidoses (MPS)
Lysosomal storage diseases: Lysosomal marker?
Mannose-6-phosphate
Lysosomal storage diseases: 2 consequences
- Primary accumulation: Incomplete catabolism
- Secondary accumulation: Impaired Autophage (accumulation of cell organelles and can trigger apoptosis)
- Accumulation of mitochondria can develop free radicals = death