Chromosomal Abberations and Open Questions (GEN) Flashcards
Down syndrome
Trisomy 21
47 (XX/XY) t21
Edwards syndrome
Trisomy 18
47 (XX/XY) t18
Patau syndrome
Trisomy 13
47 (XX/XY) t13
Angelman syndrome
Maternal deletion of 15q 11-13
46 (XX/XY) 15q 11-13
Prader-Willi syndrome
Paternal deletion of 15q 11-13
46 (XX/XY) 15q 11-13
Turner syndrome
Monosomy X
45 XO
Klinefelter syndrome
47 XXY
Huntington disease
AD
Chromosome 4 CAG repeated in HTT gene > 36 times
Higher number of repeats -> earlier symptoms (anticipation)
Myotonic dystrophy
AD
Type 1 -> 19q CTG repeated in DMPK gene
Type 2 -> 3q CCTG repeated in CNBP gene
Fragile X syndrome
X-linked dominant
CGG repeated in FMR1 gene
Friedrichs Ataxia
AR
Chromosome 9 GAA repeat in FXN gene
Cri du Chat
Deletion of 5p
46 (XX/XY) 5p-
Williams syndrome
Microdeletion of 7q 11.23
46 (XX/XY) 7q 11.23
DiGeorge syndrome
10% AD
22q 11.2 deletion (catch 22)
46 (XX/XY) 22q 11.2
Burkitt lymphoma
t(8;14) (q24;q32)
dysregulation of c-myc
Classify the complex inherited traits and diseases, give examples for each group!
Complex traits: results of multiple genetic and enviromental factors, does not behave according to mendelian laws.
Congenital malformations: cleft lip, cleft palate, neural tube defects, congenital heart diseases
Chronic adult diseases: obesity, diabetes, hypertension, autoimmune
Describe the process of X inactivation. Why, when, in whom, and how does it happen. How many X is inactivated? What is the consequence of it?
One copy of X chromosome is inactivated in female mammals.
Silenced and packed into heterochromatin.
Prevents females from having twice as many gene copies as males.
One X will be inactivated.
Visible as Barr body, periphery of nucleus.
Define proteomics:
Proteomics: large scale study of proteins. (Proteome: entire set of proteins in an organism/system)
What can be the genetic causes of Prader-Willi syndrome? Describe these genetic causes.
Paternal deletion of 15q 11-13
- deletion of Prader-Willi gene on chromosome 15
Maternal uniparental disomy
- both copies of cr. 15 from mother, both epigenetically methylated and silenced: with no paternal cr. 15 - no expression of PW gene
Wrong imprinting
- Mutation in imprinting center causes paternal PW to be silenced
Define genome:
All nuclear and mitochondrial DNA
Define pleiotropy:
The control of more than one trait by a single allele
- one gene influences two or more seemingly unrelated traits
Define mosaicism and give cause
Mosaicism: the presence of two or more populations of cells with different genotypes from a single zygote
Cause: nondisjunction
Define chimerism
Chimerism: presence of two or more cell lines of different origins (different zygote)
Cause: fusion of fraternal twins, double fertilization of egg, polar bodies
Define functional mosaicism
Functional mosaicism: identical cells use different proteins to carry out the same function
Define histone modification and list the different types; what is their significance?
Histone modification: Epigenetic processes
- Acetylation
- Methylation
- Phosphorylation
- Ubiquination
- SUMOylation
Activates/silences genes without altering nucleotide sequence
Describe the meaning of the followings: Sex linked, sex limited and sex influenced inheritance. (Do not forget to give the location of gene responsible for the trait in these different inheritances). Give one example for each.
Sex linked - gene is located on chromosome on sex chromosome (X or Y)
-> Duchenne m. Dystrophy, dystrophin, short arm of chr. X, deletion
Sex limited - gene present in both sexes, but are expressed only in one sex
- > on autosomes
- > Prostate cancer/ovarian cancer
Sex influenced - same gene shows different expression in each sex
- > on autosomes
- > body/facial hair
- > presence/absence of hormones
- > male pattern baldness
