Genetic Basis of Complex Inheritance Flashcards
What is complex inheritance?
Inheritance that does not follow mendelian inheritance
What are some inheritance patterns of complex inheritance?
Incomplete penetrance
Genomic imprinting
Extranuclear inheritance
Anticipation
What is incomplete penetrance?
People have a mutation but do not develop the symptoms of the disorder
What is genomic imprinting?
Genes expressed only from one chromosome, parent of origin dependent
(maternal or paternal gene is switched of)
What is extranuclear inheritance?
Transmission of genes that occur outside the nucleus, such as the mitochondria
What is anticipation?
Symptoms of a genetic disorder become apparent at an early age
What is penetrance?
The frequency with which a trait is manifested by individuals carrying the gene
What gene is usually responsible for cystic fibrosis?
CFTR
What are genetic modifiers?
Genes that have small quantative effects on the level of expression of another gene
What is polymorphism?
Genetic variants of a gene
What is also important for the onset of genetic diseases?
Environmental factors
What are epigenetic modifications?
Heritable changes in gene function that cannot be explained by changes in DNA sequences
What is uniparental disomy?
2 copies of a chromosome come from the same parent instead of 1 from each
What are the 2 kinds of uniparental diploidy?
Gynotypic (2 maternal genomes)
Androgenic (2 paternal genomes)
What is gynogenic uniparental diploidy?
2 maternal genomes:
Mass of embryo
Ovarian teratoma
What is andogenic uniparental diploidy?
2 paternal genomes:
Mass of placenta
Hydatidiform mole
What are examples of imprinting disorders?
Angelman syndrome
Prader-Willi syndrome
Where is mitochondiral inheritance from?
Maternal
Which has more mutations out of the nuclear genome and the mitochondria?
Mitochondria due to:
Lack of DNA repair systems
Lack of protective proteins such as histones
Damaged by reactive oxygen species
What is polyploidy?
Cell having more than 2 pairs of chromosomes
What is homoplasmy?
Cell whose mitochondrial DNA is all identical
What is heteroplasmy?
Cells whose mitochondrial DNA is not all identical
What are the 3 major myopathies?
Myoclonic epolepsy
Mitochondrial myopathy
Chronic progressive external ophthalmoplegia
What does mitochondrial disease affect?
Tissues with high metabolic demand
How can a baby have 3 genetic parents?
Sperm from dad
Egg from a mum
Mitochondrial DNA from another mum
What are examples of anticipation diseases?
Triple repeat diseases:
Huntington’s disease
Myotonic dystrophy
Fragile X syndrome
