Intro to clinical genetics Flashcards
1
Q
karyotyping process
A
- take a blood sample -> leukocytes (specifically T lymphocytes)
- add mitogen to induce replication and colchicine to degrade spindle fibers (stop division)
- stain chromosomes
2
Q
p arm
A
the short arm of a chromosome
3
Q
q arm
A
the long arm of a chromosome
4
Q
chromosome numbering
A
- 1-22 (23 is x and y) with 1 being the longest and 22 being the shortest
- except they got it wrong initially and 21 is actually a little shorter than 22
5
Q
chromosomal disorders
A
- abnormalities in number or structure of chromosome -> too many/few genes or altered genes
- polyploidy and aneuploidy
- insertions, deletions, and tranlocations
6
Q
single gene disorders
A
- alterations in coding sequence of a gene produce effects on the function of the protein
- loss (typical), gain, or alteration of function
- single genes are the basis for mendelian inheritance
- autosomal disorders and sex-linked disorders
7
Q
mitochondrial disorders
A
- most important function of mitochondria -> production of ATP
- have their own genome
- included in biochemical disorders
- non-mendelian inheritance (maternal inheritance)
8
Q
multifactorial disorders
A
•most common genetic disorders and likely the basis for many common diseases
•combination of genes and environment
Contrast with:
•polygenic = many genes acting together
•teratogenic = primarily environmental based
9
Q
important tool for diagnosing single gene disorders
A
(autosomal dominant, autosomal recessive, x-linked recessive, x-linked dominant (rare))
•always construct a pedigree
10
Q
tools for chromosome analysis
A
- karyotype
- fluorescent in-situ hybridization (FISH)
- comparative genomic hybridization (CGH)
- exome and whole genome sequencing
11
Q
FISH
A
- fluorescent in-situ hybridization
- add probe DNA lableled with fluorescent dye
- denature DNA
- if DNA sequence of interest is present, probe will hybridize
12
Q
CGH
A
- comparative genomic hybridization
- AKA microarray
- take a well plate and fix an array of DNA fragments from all chromosomes
- patient DNA and control DNA
- yellow color = normal patient DNA
- red color = deletion (control DNA overpowering)
- green color = duplication (patient DNA overpowering)
13
Q
exome sequencing
A
- looks at the exons -> determination of the sequence of coding portion of genome
- most mutations that cause disease will likely alter exons
14
Q
whole genome sequencing
A
- Expensive!
- sequence introns and exons
- will pick up mutations in promoter regions, introns, and 3’ UTRs
15
Q
problems with genetic sequencing
A
- we are all carriers for many diseases
- can detect diseases with future consequences
- sequence variation of unknown clinical significance -> counseling needed
