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93 Cards in this Set

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What is the heritability for diabetes mellitus I (DMI)?
0.6 (60%)
What may explain why DMI is not 100% concordant in monozygotic twins?
DMI may require an environmental trigger. It may be a viral exposure that triggers the autoimmune response.
What is DMI?
Autoimmune disorder. T-cells attack cells in pancreas
What is DMII?
Autoimmune? disorder where body is insulin resistant; doesn't use insulin to get glucose into cells.
What are some of the physical results of DMII?
- Leading cause of blindness
- Leading cause of lower limb amputation
- Slow wound healing
- Body uses fat instead of glucose so fat cells get into system.
What are some risk factors for DMII?
- obesity
- family history
What is the heritability of DMII?
10-15% -- complicated by cluster family issues
What is MODY - Maturity Onset Diabetes of the Young?
Insulin resistance that shows up in a person in their 20's.
Is MODY common, genetic?
MODY is rare. It appears to be genetic.
Is obesity a factor in MODY?
No, MODY is not obesity-related.
What is gestational diabetes?
Diabetes that occurs only during pregnancy when the placenta raises blood sugar too much.
Is gestational diabetes genetic?
No. Gestational diabetes is not genetic.
What is the relation of IUGR -- intrauterine growth retardation - and heart disease and DMII?
There appears to be a correlation between mothers with later heart disease and DMII.
What is the relation of IUGR -- intrauterine growth retardation -- to the World Trade Center?
An unusual number of cases of IUGR appeared in pregnant women at or near WTC on 9/11.
What is the monozygotic twin concordance rate of schizophrenia?
The concordance rate is 79%
What are the risks of having schizophrenia if
- no parents have it?
- one parent has it?
- both parents have it?
- No parents - 1%
- 1 parent - 10%
- 2 parents - 35-40%
What is the concordance in monozygotic twins for bipolar affective disorder?
79-80%
How much does the risk go up for bipolar affective disorder if 1 parent is bipolar?
5-10%
What is the heritability of eating disorders?
.5 - .8
Most of the studies on eating disorders are of siblings? How might this complicate the findings?
There might be mimicry among the siblings.
Are the sleep patterns of MZ twins similar or disimilar?
They have similar sleeping patterns.
Has any genetic link been found for narcolepsy?
They have found a gene in dogs.
What is Familial Advanced Sleep Phase Disorder?
Person has a very strict wake - sleep pattern.
Has any genetic link been found for Familial Advanced Sleep Phase Disorder?
Believed to be chromosomal. They have found a gene in hampsters that is responsible.
What is the heritability of IQ in children?

Adults?
Children 0.4

Adults 0.8
Do adopted kids show link to adoptive or biological parents relating to IQ?
Link to biological parents.
When is amniocentesis performed (age of fetus)?
Usually at 14-18 weeks, though sometimes as early as 12 weeks. Earlier, there's not enough fluid between baby and sac.
What are the risks/negatgives of amniocentesis?
- fetal loss
- leaking
- banding
- takes a week to culture sample
What is chorionic villus sampling?
Aspiration of trophoblast (chorion) cells transabdominally or transvaginally.
At what fetus age is chorionic villus sampling done?
At 11 weeks.
What is the risk of chorionic villus sampling if done earlier than 11 weeks?
Risk of shorter limbs. May be due to loss of circulation from tissue loss.
What is the risk of chorionic villus sampling over background?
Slightly more than amniocentesis. 1-3% over background
How long does it take to get results of chorionic villus sampling?
Several days.
Is karyotype used to detect "large" or small/specific problems?
Large, e.g., aneuploidy.
What prenatal test is used to check for blood disorders such as immunodeficient disorders?
PUBS - percutaneous umbilical blood sampling
How is PUBS - percutaneous umbilical blood sampling performed?
Take blood sample from umbilical cord close to placenta where there is least movement.
What are the risks of PUBS?
5% over background
- cramping, bleeding, infection, fetal loss, labor
What does the polar body diagnosis test for?
Tests for good X/bad X chromosome defect. If the polar body has the bad X, the egg doesn't and vice versa. Done before fertilization.
What is the maternal serum "quad screen" prenatal test?
It is a screen for hormones, proteins coming from fetus or placenta.
What 4 proteins does the quad screen test for?
1- AFP alpha-fetoprotein
2- hCG human chorionic gonadatropin
3- unconjugated estriol 3 from placenta
4- inhibin A
When (what age of fetus) is the quad screen done?
15 - 22 weeks (2nd trimester)
What do quad screen results indicate?
elevated levels - detects 80% of NTD neural tubal defects

low levels - detects 75% of Down/Trisomy 21

low levels - detects 60% of Trisomy 18 (Edwards syndrome)
What is fetal cell sorting?
Retrieve fetal cells (nucleated RBC's) for testing from Mom's blood.

Non-invasive.

Newest standard?
Why might women who have had children be more at risk for autoimmune disorders?
They may develop autoimmune response to fetal cells in their system. Fetal cells are 50% the woman. Then disorder may attack woman's own cells.
What is nuchal translucency?
An accumulation of fluid at the back of the fetus' neck. "Extra" fluid may indicate risk of aneuploidy's & NTD's.
At what fetal age does nuchal translucency appear?
11 weeks to 13 weeks + 6 days
How good is a nuchal translucency prediction?
About 80% accurate.
What other test, in combination with the nuchal translucency test, provides especially good screening?
Maternal serum quad screen.
How is genetic screening better than karyotyping?
You can look for gene segments, repeating units, etc.
How does gel electrophoresis sort DNA fragments?
By charge. Fragments have negative charge and are attracted to positive pole.
What is probe hybridization?
The joining of two complementary strands of DNA, or of DNA and RNA, to form a double stranded molecule.
In molecular genetics, what is a probe?
A probe is a labeled bit of DNA or RNA used to find its complementary sequence or locate a particular clone like homing in on a needle in a haystack.
What is PCR?
Polymerase Chain Reaction. Commonly used technique that leads to the selective amplification of a nucleotide sequence of interest. The amplified DNA becomes the predominant sequence in the mixture upon PCR amplification. Often used to make nucleotide probes for diagnostics.
What are 2 recombinant DNA techniques/tools?
1. Restriction enzymes

2. DNA ligase
What are restriction enzymes, and what is another name for them?
Also known as restriction endonucleases, they are bacterial enzymes that restrict the entry of foreign DNA into the bacterium by cleaving the DNA at specifically recognized sequences (restriction sites). Produces restriction fragments.
How do restriction enzymes and their DNA restriction fragments help locate polymorphism?
The RE's cleave a region of DNA. Longer fragments indicate where a sequence is NOT found.
What is EcoRI?
EcoRI is a restriction enzyme produce by E. coli that recognizes GAATTC.
What is a DNA probe?
Constructed using recombinant DNA techniques. Consists of a small piece of SS human DNA that has been inserted into a vector such as a phage or plasmid. It will undergo complementary base pairing w/specific portion of DNA.
How is the position of a hybridized probe visualized?
The blot is exposed to x-ray film which darkens at the probe's position due to emission of radioactive particles.
What are restriction fragment length polymorphisms (RFLP)?
Polymorphisms that are revealed by variation in the lengths of restriction fragments.
What is germline therapy?
Gamete alteration. Germline cells are cells that produce gametes. Change genetics of entire family line
What is somatic cells gene therapy?
Alteration of somatic cells, all cells other than germline cells.
What is recombinant DNA?
Recombinant DNA is a DNA molecule that consists of components from more than one parent molecule.
What is DNA ligase?
An enzyme that joins fragments of DNA together to form a strand.
What is transgenic?
Organisms that have had foreign DNA stably integrated into their genome
What is gene therapy?
Alteration of genetic code by introducing a non-mutated version of a gene.
What is ex vivo gene therapy?
Take cells out of body, correct in a dish, then reintroduce into the body.
What is in situ gene therapy?
Inject gene in local body place. Use vectors, agents to deliver gene, e.g., viruses.
What is in vivo gene therapy?
Introduce gene into circulation.
What is SCID?
severe combined immunodeficiency
What happened to Jesse Gelsinger in 1999?
He was patient in trial of in vivo therapy for a metabolic disorder. Virus was introduced instead of good hepatic gene.
What are requirements for new gene therapy trials?
1. know disease & how it's caused
2. previous animal model
3. in vitro success
4. show there are no alternatives for patients
5. prove safety
How has severe immunodeficiency been fixed w/recombination?
Restriction enzymes used to make cut out of mutation and give cell desired "patch" replacing mutation.
What is HAC, human artificial chromosome?
A vector used to transfer or express large fragments of human DNA. HACs behave and are constructed like human chromosomes. Idea of use has waned.
How can RFLP help determine parents?
Every child fragment has to be found in either mother or father, or they are not the parents.
What is "semi-conservative" replication?
Replication in which there would always be two DNA double-stranded molecules carrying the original mother strands, each in intimate embrace with newly synthesized strands.
What method is used to get enough DNA for sampling, i.e., how do you amplify DNA?
PCR - polymerase chain reaction

1. Heat, denature into strands
2. Cool so primer can bind to the ends of the DNA strands
3. Reheat, polymerase makes copy
Copies
Repeat
What is an oligonucleotide?
DNA sequence consisting of a small number of nucleotide bases.
What is a SNP?
Single nucleotide polymorphism. DNA sequence variations that occur when a single nucleotide (A,T,C,or G) in the genome sequence is altered. Must occur in at least 1% of population. Could predispose people to disease or influence their response to a drug.
What is a polymorphism?
Common variation or mutation in DNA.
What % of genes in a simple life form is devoted to the plasma membrane?
30%
Does a more complex organism mean more genes?
No. There are approx 289 disease-causing genes. Fruit fly has 177 of them. A lot have been conserved over evolution.
What is proteomics?
Study of proteins
Are genes in a human static or changing? Proteins?
Genes are static.

Proteins are always changing.
Is there a PCR for proteins?
Not so far. Huge.
How was dog recently cloned?
Somatic cell nuclear transfer: enucleate egg from dog; fuse donor cell from dog w/egg. The egg/cell grows & divides into embryo. Implant embryo.
What is nanotechnology?
Manufacture of objects whose components are only 100's of nanometers in size.
How were nanoshells used to kill tumors.
Tumors have lots of fenestrated capillaries. Shells fit thru fenestrations, got embedded in tumors. Heated by specific wavelengths of light. Cooked tumors w/o injuring healthy cells.
What are examples of nanotechnology?
- engineered capillary endothelium that secretes "teflon"

- clean up water with nano-magnets
What questions do you ask if you encounter disorder in patient w/negative family history?
1. new spontaneous mutation?
2. variable expression? parent may have had very mild unnoticed case?
3. incomplete penetrance? germline mosaicism in parents?
4. misdiagnosis?
5. false paternity?
What should you expect of a genetic counselor?
1. understand diagnosis/course of tx; anticipatory guidance, tx options

2. hereditary basics, recurrence risk

3. alternatives

4. guidance appropriate to that family, including its perception of the risk

5. treat family as whole, as group
What should you NOT expect of a genetic counselor?
1. "Directiveness". A gen counselor is non-directive (a clinician is moreso).

2. dedication to curing the disorder
What are some applications of recombinant DNA techniques?
- genetically modified food
- genetically modified animals
- chemical resistant, e.g., Roundup, crops