Biochemistry - Genetic Testing

Front 1

what is the goal of newborn screening?

Back 1

early recognition of a disorder so that intervention will prevent or reverse the disease process

Front 2

what is the goal of heterozygote screening?

Back 2

to identify unaffected carriers of a disease gene who can then be given information about risks for having affected offspring and reproductive options

Front 3

for which types of diseases is heterozygote screening normall performed?

Back 3

autosomal recessive

Front 4

when can standard amniocentesis be performed during pregnancy?

Back 4

15-18 weeks

Front 5

when can chorionic cillus sampling (CVS) be performed during pregnancy?

Back 5

9-12 weeks

Front 6

when can early amniocentesis be performed during pregnancy?

Back 6

11-15 weeks

Front 7

when can ultrasound be performed during pregnancy?

Back 7

the entire time

Front 8

when can fetal blood sampling be performed during pregnancy?

Back 8

18 weeks

Front 9

what are 5 reasons to perform prenatal diagnosis?

Back 9

maternal age >35, previous child with chromosome abnormality, history of structural chromosome abnormality in one of the parents, family history of genetic defect diagnosable by biochemical or DNA analysis, and risk of neural tube defect

Front 10

what are the drawbacks of genetic sequencing for direct genetic diagnosis?

Back 10

it is expensive and does not guarantee detection of the mutation responsible for the disease in the family

Front 11

what are 3 possibilities for a false negative in genetic sequencing for direct genetic diagnosis?

Back 11

1) patient does not have a mutation in the tested gene, 2) patient has a sequence alteration that cannot be detected by sequence analysis, or 3) patient has a sequence alteration in a region of the gene not covered by the laboratory's test

Front 12

for what does ASO stand?

Back 12

allele specific oligonucleotides

Front 13

what must be known to perform ASO?

Back 13

the DNA sequence surrounding a mutation

Front 14

which DNA sequences are used as probes in ASO?

Back 14

the mutation sequence and the normal sequence

Front 15

what is a dot blot? A reverse dot blot?

Back 15

when the test DNA is spotted on a membrane and ASOs for mutation and normal types are added; when the ASOs are attached to the membrane and the test DNA is the probe

Front 16

what is a disadvantage of ASO technique?

Back 16

it is not useful to detect rearrangements of genes such as large deletions

Front 17

which technique is used to identify gene expression profiles in cancer, for example?

Back 17

microarray analysis

Front 18

what is microarray CGH?

Back 18

when microarray is used to identify loss and gain of genetic material

Front 19

do microarrays usually use the dot blot of reverse dot blot principle?

Back 19

reverse dot blot

Front 20

what is not detected in microarray CGH?

Back 20

balanced rearrangements or mosaicism for gain/loss of chromosomes or chromosomal segments

Front 21

at what does indirect genetic diagnosis look?

Back 21

DNA polymorphisms linked to the disease gene to determine whether an individual has inherited a chromosome containing the disease gene from his or her parent

Front 22

what are 2 disadvantages to indirect genetic testing?

Back 22

need to type multiple family members and possibility of recombination

Front 23

what is presymptomatic testing?

Back 23

testing of individuals who will develop the disease, if they carry the disease phenotype

Front 24

do predictive tests deal with probabilities or certainties?

Back 24

probabilities

Front 25

does detection of mutations in a gene reveal the severity of the disease?

Back 25

no