Atypical Modes of inheritance Flashcards
What is Y linked inheritance? How many traits and which ones?
Also called holandric - only affects males. Hairy ears - hypertrichosis and retinitis pigmentosa
What is retinitis pigmentosa? What does it lead to?
Degenerative disease of retina causing pigment deposition in the periphery of retina. Leads to cone and rod dystrophy. Results in night blindness and progressive loss of visual field.
Mutations on how many different genes can cause retinitis pigmentosa?
50 different gene
What is digenic inheritance of retinitis pigmentosa? What is ths autosomal recessive gene? What protein causes heterozygotes to manifest the disease?
Disorders determined by the additive of 2 different gene loci? AR - Peripherin-2 PRPH2. Heterzygotes - ROM1
What is locus heterogeneity? What does it mean?
Conditions that are determined by mutations in more than one gene. Affected parents can have healthy children if the parents carry mutations on different genes.
What is epigenetics?
The study of regulation of gene activity that is not dependent on gene sequence and includes heritable and non-heritable alterations in gene activity and transcriptional potential of a cell. Includes gene regulation by histone modifications marks
What are histones and what do they do?
Histones are positively charged proteins that bind to DNA and regulate the DNAs packing.
DNA Packing: explain Acetylation/Phosporylation vs Methylation
Acetylation and phosphorylation often decreases packing and methylation increases packing
What is a keys source of the one carbon group used to methylate DNA?
Folate
What is the most important methyl donor in mammals? What does it help methylate?
SAM S-adenosyl-methionine. Methylates proteins, nucleic acids, lipids, neurotransmitters and creatine synthesis
What is a CpG island? What happens if they are colocalized with promoters?
Atleast 200bp with more than 50% GC percentage. When colocalized with promoters and other regulatory regions, it is generally associated with gene REPRESSION.
How is methylation speculated to silence transcription?
A methyl group in the major groove of the DNA may prevent stable binding of transcription factors.
Do epigenetic marks get passed on to progeny?
Widespread removal of epigentic marks following fertilization (stem cells) but some epigenetic marks can survive and determine parent-of-origin genomic identity
What is genomic imprinting?
When certain genes are expressed in a parent of origin manner. Its a special case of epigenetic regulation of gene expression
What two diseases can deragulation of genomic imprinting result in? What is it caused by?
Prader-willi syndrome and Angelman syndrome. Deregulation of epigentic marks on 15q11-q13
