Genetics: Modes of Inheritance Flashcards Preview

Biochemistry > Genetics: Modes of Inheritance > Flashcards

Flashcards in Genetics: Modes of Inheritance Deck (20)
Loading flashcards...
1

Autosomal Dominant Disease Homozygotes

Usually lethal

2

Achondroplasia

Dwarfism from AD FGFR3 mut

3

Hemizygous

Males are for all genes on X chromosome

4

Allelic Heterogeneity

Different mutations in same gene may cause the same disease

5

Compound Heterozygosity

2 different abnormal alleles at the same locus in an individual

6

Locus Heterogeneity

Different muts in different chromosomes causing the same disease

7

Sex Limitation

Autosomal dominant disorder expressed exclusively in males

8

Mosaicisim

Ocurrence of 2+ cell lines with different genetic or chromosomal constitutions

9

2 Kinds of Mosaicism

Germline - some of germ cells are, mutation transferred to offspring as affected, not mosaic
Somatic - milder/segmental phenotype, cannot be passed to offspring unless present in germline

10

Classic Pedigree of Mt Inheritance of Disease

Woman affected, all her children are affected, none of the children of her sons are affected

11

4 Differences b/w Nuclear and Mt Genome

Mt WAY smaller/fewer genes
Mt ring-shaped
Mt way higher percentage of coding DNA
Mt no introns

12

Heteroplasmy

An mtDNA variant is found only in a portion of cell's mt

13

Homoplasmy

All mtDNA copies have same sequence/mut

14

3 Mitochondrial DNA Point Mutation Diseases

tRNA gene: Mitochondrial encephalomyopathy (MELAS)
ATPase gene: Neuropathy, ataxia, and retinitis pigmentosa (NARP)
ETC Complex 1: Leber's hereditary optic neuropathy (LHON)

15

3 Mitochondrial DNA Large Deletions Diseases

Chronic progressive external ophthalmoplegia (CPEO)
Kearns-Sayre (triad of CPEO, bilateral pigmentary retinopathy, and cardiac conduction abnormalities)
Pearson Syndrome (a lot of shit)

16

Disease Concordance b/w Monozygotic and Dizygotic Twins by Genetic or Multifactorial Cause

Genetic: MZ 100%, DZ up to 50%
Multifactorial: MZ <100%, DZ less than MZ

17

Heritability

Proportion of total phenotypic variance of a condition which is caused by genetic variance

18

Threshold Theory of Qualitative Traits

Susceptibility (liability) depends on the combined small effects of many genes and shows a bell-shaped distribution in the population, and only proportion of individuals exceeding a certain threshold develop the disease

19

Qualitative vs. Quantitative Trait

Qualitative is dichotomous, quantitative continuous

20

5 Factors Contributing to Higher Liability

Number of affected relatives
Severity of phenotype
Individual is affected w/ disease that has low incidence in general pop
Proportion of genes in common w/ affected family relatives (closeness of relation)
Affected individual belongs to less frequently affected gender