What is an obligate carrier?
Someone who may be clinically unaffected but must carry a gene mutation based on analysis of the family history
How to know if a disease is mitochondrially inherited?
All children must be affected
What is GWAS used for?
- To study polymorphims and polygenic disorders.
- Snips are made at genes and their significances are looked at
- Large sample size needed
- Alleles that are rare have a greater effect but those that are common, each allele has a lower effects and many are needed for an effect
What is pleitropy?
a single gene that may give rise to two or more apparently unrelated effects - e.g. effects on different parts of the body
Penetrance and expressivity
Penetrance – does the disease manifest?
Expressivity – how does the disease (or trait) get expressed?
How is a karyotype made?
- A karyotype is a pictorial display of metaphase chromosomes
from a mitotic cell - When chromosomes condense they are visible under a light
microscope - Mitotic cells are fixed in metaphase and the chromosomes
are stained with Giemsa dye.
Giemsa stain
This stains regions with lots of Adenine (A) and thymine
(T) base pairs giving a pattern of dark bands on each chromosome
Karyotype notation
-Total number chromosomes, sex chromosomes, any
extra/missing chromsomes
e. g. 46, XY
e. g. 47, XX, +21
What can cause aneuplodies?
Aneuploides result from failure of separation of homologous chromosomes in anaphase I or sister chromatids in anaphase II of meiosis. This is called non-disjunction.
