Genetic Testing

Question 1

genetic tests can be used to determine

Answer 1

the genetic cause of a disease
confirm a suspected diagnosis
predict future illness
detect when an individual might pass a genetic mutation to his or her children
screen newborns, fetuses or embryos used in in vitro fertilization for genetic defects.

Question 2

informed consent

Answer 2

the process of educating a person about the test and obtaining permision to carry out testing.

Question 3

informed consent can only be given by adults who are

Answer 3

competent to make medical decisions for themselves.

Question 4

diagnostic testing is used to

Answer 4

diagnose, rule out or rule in a specific genetic disease.

Question 5

diagnostic testing is used to confirm a diagnosis when

Answer 5

a particular condition is suspected based on symptoms and/or family history.

Question 6

types of diagnostic tests

Answer 6

chromosome analysis
biochemical diagnostics
DNA diagnostics
exome sequencing

Question 7

chromosome analyses - karyotype procedure

Answer 7

blood sample is culture and treated with a mitosis blocker. It is centrifuged and placed on a microscope glass slide and the chromosomes are stained and look at under a microscope.

Question 8

biochemical diagnostic testing involves

Answer 8

the measurement of enzymes/metabolites to determine if they are abnormal in some way.

They may be done from blood, urine, spinal fluid or other tissue samples, depending on the disease.

Question 9

DNA testing

Answer 9

identification of specific disease causing mutation
identification of causative gene/mutation in undiagnosed mendelian diseases
techniques

Question 10

DNA testing: identification of specific disease causing mutation

Answer 10

confirm clinical or biochemical diagnosis
identify carriers, especially for X linked traits.
accurate prenatal diagnosis.

Question 11

single gene test

Answer 11

minimal locus heterogeneity
distinctive clinical findings clearly point to a specific gene
Limitations of NGS sequencing technology to detect trinucleotide repeat disorders and disorders with epigenetic abnormalities.

Question 12

gene panel

Answer 12

heterogeneity
disorders with overlapping phenotype - differential diagnosis
disorders share one manifestation but may have completely different overall presentation.
Diseases assoicated with genes from a common pathway structure.

Question 13

principal indications for prenatal diagnosis

Answer 13

maternal age >35 years
previous child with chromosome or biochemical abnormality.
presence of structural chromosome abnormality in oen of the parents.
family history of a genetic disease that may be diagnosed or ruled out by biochemical or DNA analysis.
parents diagnosed as carriers of a recessive disease after a population screening test.

Question 14

methods of prenatal diagnosis

Answer 14

invasive testing:
chorionic villus sampling (10 - 11 weeks after LMP)
amniocentesis (15 - 17 weeks after LMP)

noninvasive testing
maternal serum alpha fetoprotein
1st and 2nd trimester maternal serum screening
fetal DNA in maternal blood.

Question 15

cells obtained by either CVS or anmno can be analyzed directly or cultured for

Answer 15

chromosome analysis
measure substrate level/enzyme activity
source of DNA for mutation detection

Question 16

detection of genomic disorders

Answer 16

submicroscopic chromosomal deletions/deuplications

Question 17

fetal DNA in maternal blood

Answer 17

now mainly trisomies
several commercial methods in development
non-invasive 20 - 30 mL of mother’s blood.

Question 18

microdeletion FISH panel: combined frequency

Answer 18

1 in 430 to 1000

Question 19

array comparative genomic hybridization (aCGH)

Answer 19

detects submicroscopic gain gain or loss of genetic material
CNVs may be pathogenic, benign or of unknown significance.
widely used in postnatal diagnosis of MR/multiple congential anomalies when chromosomes have been normal.

Question 20

aCGH general screening

Answer 20

1 in 250 positive

Question 21

cfDNA comes from apoptotic cells derived from

Answer 21

maternal circulation (adipocytes, white blood cells)
fetal (placental cells (trophoblasts) in the maternal circulation)

Question 22

commercial noninvasive prenatal testing - trisomies tested

Answer 22

13, 18, 21

Question 23

natera’s panorama - genetic testing method

Answer 23

single nucleotide polymorphism

Question 24

verinata’s verifi - genetic testing method

Answer 24

massively parallel sequencing

Question 25

sequenom’s materniT21 plus - genetic testing method

Answer 25

massively prallel sequencing

Question 26

ariosa’s harmony - genetic testing method

Answer 26

chromosome selective sequencing

Question 27

present use of noninvasive prenatal testing

Answer 27

trisomies 13, 18, 21

sex chromosome abnormalities

Question 28

future uses of noninvasive prenatal testing

Answer 28

single gene defects
small microdeletion/duplication
CNVs 
methylation patterns (epigenetics)

Question 29

NIPT is not a

Answer 29

diagnostic test for fetal aneuploidy, and therefore a positive NIPT result requires an invasive test to confirm the findings.

Some therefore consider there to be insufficient evidence to support the use of NIPT for screening in the general population.

Question 30

preimplantation genetic diagnosis

Answer 30

refers to genetic profiling of embryos prior to implantation.

Question 31

5 main groups of patients that might utilize preimplantation genetic diagnosis (PGD)

Answer 31

pateints that are having IVF with advanced maternal age
patients of any aged with repeated IVF failure (3 more more failed attempts)
to screen or inherited genetic diseaes
patients that are carriers of chromosomal translocations.
patients that have had recurrent miscarriages.

Question 32

A recent study found that babies born after PGD testing had

Answer 32

no increased risk of congenital malformation and no adverse effect on growth.

Question 33

presymptomatic testing

Answer 33

applies to disorders with virtually complete penetrance

positive DNA test indicates patient is affected and will eventually develop disease symptoms.

Question 34

predispositional testing

Answer 34

applies to disease with reduced penetrance

positive DNA test confers increased risk of disease but that doesn’t predict that patient will manifest the disease.

Question 35

predictive testing has significant psychosocial risks

Answer 35

genetic counseling and psychosocial support required.

risk of insurance or employment discrimination

Question 36

presymptomatic testing - definitition

Answer 36

testing to determine if a patient will develop a childhood or adult-onset disorder.

It may be offered to individuals who have a family history of a specific genetic disease.

Question 37

diseases tested with predispositional testing

Answer 37

genetic disease with reduced penetrance (presence of a mutatnt gene confers increased risk of eventual disease, but does not predict that any particular patient will get the disase)

Question 38

predispositional testing is available for

Answer 38

BRCA1 and 2 genes in breast/ovarian canver

Question 39

carrier testing is used to

Answer 39

identify people who carry one copy of a gene mutation which causes autosomal recessive disorders.

Question 40

carrier testing is offered to

Answer 40

individuals who have a family history of an AR genetivc disorder
people in certain ethnic groups with an increased risk of specific genetic conditions.

Question 41

direct to consumer genetic testing

Answer 41

direct to consumer genetic testing refers to genetic tests that are marketed direclty to consumers. It provides access to a peron’s genetic information without necessarily involing a doctor or insurance company in the process.

Question 42

most famous direct to consumer company

Answer 42

23 and me

it was stopped from interpreting data since they were not clearly explaining results.

Question 43

There are more than __ genetic tests for over 4,000 diseases and conditions in the national instituate of health’s genetic testing registry.

Answer 43

There are more than 14,000 genetic tests for over 4000 diseases and conditions in the national institute of health’s genetic testing registry.