Week 3: Genetic Conditions Flashcards
De novo mutations are most common in which type of inheritance
Autosomal dominant
What is the inheritance of cystic fibrosis
Autosomal recessive
What is cosanguinity
Relationship between second cousins or closer
Genetic testing is not currently done in children under what age
18yo
Clinical features of DiGeorge syndrome (22q11.2)
CATCH 22
- Cardiac
- Abnormal facial features
- Thymic aplasia
- Cleft palate
- Hypo-PTH, Hypo-calcaemia (due to aplasia of parathyroid gland)
Why do pts with DiGeorge syndrome (22q11.2) tend to get autoimmune disease
Thymus gland not developed, so cannot regulate self tolerance
Definition of anticipation in genetic dz
Disease becomes more severe/ has earlier onset in each subsequent generation
Definition of incomplete penetrance in genetic dz
Not everyone with the genotype will express the phenotype
Definition of genetic heterogeneity in genetic dz
A number of different genes can cause the same phenotype
eg long QT syndrome
Definition of variable expressivity in genetic dz
Many different phenotypes from the same genotype
Definition of imprinting in genetic dz
Phenotype depends on which parent the gene was inherited from
eg Angelman, Prader-Willi
Definition of mosaicism in genetic dz
Multiple cells with different genotypes in 1 individual (due to mitotic errors)
Give the names of the following trisomies:
13
18
21
13: Patau’s
18: Edward’s
21: Down’s
Give the name of the following sex chromosome aneuploidies:
X0
XXX
XXY
X0: Turner’s syndrome
XXX: Klinefelter’s syndrome
XXY: Triple X syndrome
Which aneuploidies are associated with low IQ
- All the trisomies (21, 18, 13)
- Triple X syndrome
Heart complications associated with Down’s syndrome
- AVSD/ VSD
- Tetralogy of fallot
- PDA
Down’s syndrome is associated with increased risk of which cancers
- Testicular cancer
- ALL
- AML
Heart complications associated with Patau’s syndrome
- VSD
2. PDA
Heart complications associated with Turner’s syndrome
- Bicuspid aortic valve
- Aortic valve stenosis
- Coarctation of aorta
Which of the following are increased/ decreased in Down’s screening:
beta-hCG AFP PAPP-A Inhibin A Estriol Nuchal translucency
DECREASED
- AFP
- PAPP-A
- Estriol
INCREASED
- Nuchal translucuency
- beta HCG
- Inhibin A
Components of Down’s syndrome triple and quadruple test
Triple test
- betaHCG
- AFP
- Estriol
Quadruple test
above +
4. Inhibin A
Difference between incomplete penetrance & variable expressivity
Incomplete penetrance: gene may or may not be expressed. Same phenotype if gene is expressed
Variable expressivity: gene will be expressed but not all the features appear in the phenotype
