REPRO_TEST 1: Thatcher_Clinical Genetics Flash Cards

Study Save to My Flashcards Offline Study Print Export to file

Play Memory | Create Card File | Append to Card File

Card Set Properties

Title:	REPRO_TEST 1: Thatcher_Clinical Genetics
Description:	RT
Number of Cards:	31
Save Count:	1
Author:	dabunn9
Created:	2012-02-07
Tags:	dabunn9 repro wvsom
Private	No

Save Count represents the number of people who have saved this card set to their flashcard list. Consider this an endorsement!

- Question
- Answer
- Side 3

- What is Phenocopy?
  
  Genocopy?
- BOTH REFER TO PHENOTYPE
  
  Phenocopy – a phenotype produced by non-genetic causes, that is similar to a phenotype produced by genetic causes (caused by environment or genetic causes)
  
  Genocopy - similar phenotypes produced by different genotypes (caused by different genetic causes)
- How can ambiguous genitalia in females be an example of phenocopy?
- can be due to being exposed to exogenous androgens in utero
  
  OR
  
  virilizing 21-hydroxylase deficiency
  
  (either environmental or genetic cause!)
- define
  Allelic heterogeneity
  
  Locus Heterogeneity
- allelic: multiple mutations within the same gene can produce the same phenotype
  
  locus: different genes have mutations causing the same phenotype
- what are the following an example of:
  
  Anemias caused by different mutations at the β-globin gene locus
  
  Over 1000 different CFTR mutations causing cystic fibrosis
  (delta 508 most common)
- Allelic heterogeneity - Similar phenotypes produced by different mutations at the same gene
  
  (Form of genocopy)
- what is the following an example of:
  
  SCIDS
  Osteogenesis Imperfecta
  Ehlers-Danlos Syndromes
  Charcot-Marie-Tooth Disease
  Familial Parkinson Disease
- Locus Heterogeneity - similar phenotypes produced by mutations at different gene loci
  
  (Form of genocopy)
- what is the difference btw allelic heterogeneity and polymorphism?
- Polymorphism will not produce the same phenotype, whereas allelic heterogeneity would
  
  polymorphism also has to have frequency above 5%
- define Polygenic Traits
- phenotypes determined by multiple genes.
- what is meant by non-syndromic?
- the gene alteration only causes one problem (ex: causes deafness only, and not other symptoms)
- what is meant by pleiotropy?
- A single gene controls multiple traits
- Marfan syndrome is a mutation in what?
- fibrillin gene (chromosome 15)
- Tall Stature
  Arachnodactyly
  Dolichostenomelia
  Myopia; dislocated lenses
  Aortic root dilatation; risk for aortic aneurysms
  
  what is this? mutation in?
- Marfan Syndrome
  
  Mutations in fibrillin gene (chromosome 15)
- What are the two forms of neurofibromas?
- plexiform: more neural tissue
  
  dermal
- pt presents with cafe au lait spots, and a bunch of pedunculated skin patches diffusely spread across the body...what does this pt have?
- Neurofibromatosis 1 (NF1)
  
  Gene product: neurofibromin (a GAP)
  
  (also known as von Reklinghausen disease)
- Genetic variablitly is commonly demonstrated by what genetic problem?
- Osteogenesis imperfecta
  
  Differences in degree of the phenotype produced by the same genotype
  
  In general, autosomal dominant disorders tend to be more variable than autosomal recessive disorders
- please describe Osteogenesis Imperfecta Types 1 & 2..include the underlying genetics
- both: Brittle Bone Disease (AD mutation of COL1A1/2 genes)
  
  type 1: blue sclerae
  
  type 2: multiple interuterine fractures (more serious)
- what is Incomplete or Partial Penetrance?
  
  Example?**
- a mutation which does not produce a mutant phenotype in everyone who inherits the mutant genotype (Percentage of the pple who have the phenotype that actually show it...)
  
  BRCA genes (AD-tumor suppressor genes)
  BRCA1 ~85% by age 65 years
  BRAC2 ~35% lifetime risk
- Which BRCA gene is more likely to cause male breast cancer?
  
  what about ovarian/bowel/prostate
- male breast: BRCA 2
  
  varian/bowel/prostate: BRCA 1
- What is Codominance? classic example?
- Codominance - different alleles inducing independent effects on the phenotype
  
  Blood groups
- What is mitochondrial inheritance?
- Maternal Inheritance – transmission from mothers to all children regardless of sex, never transmitted from fathers to any children
  
  note: within the mitochondria population you will have some that have the mutation and some that don't (this is known as heteroplasmy)
- What is Anticipation?
- A mutant phenotype that increases in severity each generation
- Fragile X syndrome is an example of what genetic term
- Anticipation: A mutant phenotype that increases in severity each generation
- Pt has a mental retardation, but still maintains a moderate IQ. They also present with a long face, prominent jaw, and forehead. You notice the person is hyperactive and tends to flap his hands..what does he have? Genetics? Example of what genetic property?
- FRAGILE X
  
  due to FMR1 Gene
  
  Anticipation: A mutant phenotype that increases in severity each generation
  
  Most common heritable mental retardation (moderate IQ***)
  Second only to Down
  Hyperactivity
  Hand flapping
  Biting
  Temper tantrums
  Poor eye contact
  
  After puberty
  long face***
  prominent jaw and forehead***
  large ears
  macro-orchidism (large testicles)
- 3 examples of trinucleotide expansion diseases?
- Fragile X
  
  Huntington
  
  Myotonic Muscular dystrophy
- how does anticipation occur in Fragile X syndrome?
  
  **
- the first person has a number of CGG repeats
  
  in the next generation you have even more copies of the CGG repeat
  
  by the third generation you might have >200 repeats
  
  this leads to methylation (inactivation) of the promotor, so you knock out the gene getting a serious defect
- Epigenic imprinting is what? Key example?
- A mutant genotype with a different phenotype depending on context (e.g. the sex of the patient)
  
  e.g.
  Prader-Willi and Angelman Syndromes
- What is Prader-Willi Syndrome? (presentation and cause)
- Neonatal hypotonia/feeding problems (gradually improvement)
  Obesity due to compulsive feeding (after 12-18 months)
  Almond-shaped eyes
  Hypopigmentation
  Upslanted palpebral fissures
  Bitemporal narrowing
  Mild MR/learning disabilities
  Behavior problems
  Small hands and feet
  Hypogonadism
  Small genitalia (penis/clitoris/scrotum/labia)
  
  due to paternal chromosome 15 (microdeletion due to methylation of the middle gene--genomic imprinting)
- What is Angelman Syndrome? (presentation and cause)
- Happy disposition (paroxysms of laughter)
  Severe mental retardation
  Jerky, ataxic movements and gait (puppet-like)
  Prominent mandible/pointed chin
  Wide mouth
  Arm posturing
  Absent speech
  Seizures
  Thin upper lip
  Widely spaced teeth
  Microcephaly
  Hypopigmentation
  
  due to maternal chromosome 15 (microdeletion due to methylation of outer genes--genomic imprinting)
- Penetrance vs. Non-penetrance
- **Penetrance**
  mutated individual who demonstrates a phenotype
  
  **Non-Penetrance**
  mutated individual who DOES NOT demonstrate any phenotype
- What is Genetic Variability?
- Differences in degree of the phenotype produced by
  the same genotype
  
  (Twin Studies used to evaluate)
- Mendelian traits vs. Non-Mendelian traits
- Mendelian = AD or AR patterns
  
  Non-Mendelian = any other patterns
- Mendelian traits are _____ or ____ inheritance patterns
- AR or AD