MI Unit 2 test

what is genetic testing?

techniques used to detect genetic mutations

single gene: autosomal dominant

dominant gene on one of 44 non-sex chromosomes, need 1 bad allele

example of autosomal dominant disorder

Huntington’s

single gene: autosomal recessive

recessive gene on one of 44 non-sex chromosomes need 2 bad alleles

example of autosomal recessive disorder

Tay-Sach’s disease

single gene: sex-linked

gene usually carried on X chromosome

sex linked disorder example

color-blindness

multifactorial mutation

combination of many genes and environmental factors

multifactorial disease example

cancer

chromosomal mutation

missing/damaged chromosome

chromosomal disorder example

Down syndrome

mitochondrial mutation

found in mitochondrial DNA, only passed on from mother

carrier screening

uses pedigrees + genetic testing to determine if parents/family members are carriers of a genetic disease

preimplantation genetic diagnosis

test embryo after IVF for mutations

fetal screening

use of amniocentesis, chorionic villi sampling, and ultrasounds to diagnose fetus abnormalities

newborn screening

screen newborns for most common abnormalities

duties of a genetic counselor

analyze genetics w/in families, parents, and ethnic groups to determine the chances of having a child w/ a specific disease, then advising family + providing options

goal of PCR

to make many copies of target gene

steps of PCR process

denaturation, annealing, extension, x30 cycles of exponential amplification

denaturation

temp increased to separate DNA strands

annealing

temp decreased to allow primers to base pair to complementary DNA template

extension

polymerase extends primer to form nascent DNA strand

primers

short segment of DNA, marks beginning and end of target gene

DNA taq polymerase

enzyme, adds free nucleotides to DNA strand

thermal cycler

changes temps needed for PCR quickly

genotype

allele/gene combination person inherits

Single Nucleotide Polymorphism/SNP

single base pair change in either coding/non-coding part of genome, changes # of cuts, results in diff # of bands

hCG-PAPP-A

blood test, measures hormone levels, too high/low = problems

NT ultrasound

measures fluid around neck, high levels = problems

Cell Free Fetal DNA

blood test, DNA from fetus released from placenta + tested for chromosomal abnormalities

Quad screen

blood test, measures hormone + protein levels, too high/low = problems

gene therapy

alteration of genes of person afflicted w/ genetic disease

vectors

agent (plasmid/virus) that carries modified genetic material, can be used to introduce new genes into organism

insert

insert functional gene, gives body means to make correct protein, good for recessive disorders

disable

dysfunctional gene disabled, allowing other proteins to be made, good for dom. disorders

repair

dysfunctional gene repaired so it can produce functional proteins

CRISPR

mechanism found in bacteria to protect from viruses

Cas9

protein, contains cDNA to target gene, cuts DNA when match is formed

IVF

eggs removed from woman, joined w/ sperm in test tube

preimplantation genetic testing

analyzes embryo for genetic defects prior to implantation

PGT-A

tests for aneuploidy (extra/missing chromosomes)

PGT-M

tests for mutations of single gene

PGT-SR

tests for structural rearrangements

carrier screening done on parent

prior to IVF to see if they have recessive gene

retrovirus

RNA, up to 8,000 bp, targets dividing cells but gene inserted randomly (can cause side effects), may produce immune response

adenovirus

up to 7500 bp, targets variety, may produce immune response, efficient initially but results temporary

adeno-associated virus

up to 5000 bp, targets variety, no immune response, highly efficient, inserts into chromosome w/out disrupting genome, lasting results

herpes simplex virus

up to 20,000 bp, gene not put into genome, only infects nervous system, may cause immune response, naked DNA + liposome = no immune response, not specific to any cell type, any size DNA, less efficient, temporary results

lentivirus

up to 8500 bp, targets variety of cells, no immune response, integrates into host, can disrupt existing genes