Biochem: Genetic Screening and Therapy

Question 1

How is PKU screened in newborns?

Answer 1

Guthrie Test: blood drop from heel stick tested for high levels of Phe

Question 2

Different between sensitivity and specificity.

Answer 2

Sensitivity: ability to correctly identify affected individuals

Specificity: ability to correctly identify Unaffected individuals

Question 3

What disorders are looked for in newborn screening?

Answer 3

PKU, galactosemia, hypothyroidism, Hb disorders, DMD

Question 4

When are presymptomatic screenings conducted?

Answer 4

Diseases that show anticipation patterns of heredity.

Huntington, breast cancer, polycystic kidney disease

Question 5

Molecular tool used to look for a mutation when the gene is question is not known.

Answer 5

Linkage Analysis

Question 6

Molecular tool used for screening, however, the exact sequence of DNA in the mutated gene must be known.

Answer 6

Allele-Specific Oligonucleotide (ASO)

Question 7

Reasons why molecular analyses are not 100% accurate

Answer 7

Genotyping errors
Mosaicism
Incomplete penetrance

Question 8

What is pseudomosaicism?

Answer 8

Analyzing cell growth of a test subject during genetic screening often causes abnormal cellular behavior because no laboratory environment exactly mimics the endogenous environment of the body.
(most common in amniocentesis screening)

Question 9

What fetal disease states are being tested for in a pregnant patient that has high levels of alpha-fetoprotein (AFP)?

Answer 9

Neural tube Defects: spina bifida, anencephaly

Body Wall Defects: omphalocele, gastroschisis

Question 10

What is susptected in a mother with low AFP?

Answer 10

Down Syndrome or Trisomy 18

Question 11

Which viruses are used as vectors in gene therapy?

Answer 11

Adenovirus

Retroviruses (Lentivirus)

Question 12

What are the limitations for each viral vector?

Answer 12

Adeno: immune response in host
Lenti: only can insert into dividing cells, can interrupt normal genes