Biochem mutations

Question 1

MOA of hydroxyurea

Answer 1

• inhibits ribonucleotide reductase

Question 2

MOA of 6MP

Answer 2

• blocks de novo purine synthesis

Question 3

MOA of 5-FU

Answer 3

• inhibits thymidylate synthase (decreased dTMP)

Question 4

MOA of methotrexate

Answer 4

• inhibits dihydrofolate reductase (decreased dTMP)

Question 5

MOA of trimethoprim

Answer 5

• inhibits bacterial dihydrofolate reductase (decreased dTMP)

Question 6

enzyme deficient in Lesch-Nyhan syndrome

Answer 6

• HGPRT

- presents with MR, self-mutilation, aggression, hyperuricemia (orange sand crystals), and gout

Question 7

enzyme deficient in SCID

Answer 7

• adenosine deaminase

- presents with recurrent infections and decreased lymphocyte count

Question 8

mutation found in xeroderma pigmentosum

Answer 8

• nucleotide excision repair

Question 9

mutation found in HNPCC

Answer 9

• mismatch repair

Question 10

mutation found in ataxia telangiectasia

Answer 10

• nonhomologous end joining

Question 11

enzyme inhibited by Amanita phalloides mushrooms

Answer 11

• RNA polymerase II

Question 12

cause of I-cell disease

Answer 12

• failure of addition of mannose-6-phosphate to lysosome proteins

Question 13

mutation found in Chediak-Higashi

Answer 13

• mutation found in the lysosomal trafficking regulator gene (LYST)

Question 14

mutation found in Kartagener’s

Answer 14

• immotile cilia due to a dynein arm defect

Question 15

cause of osteogenesis imperfecta

Answer 15

• abnormal type I collagen

Question 16

cause of Ehlers-Danlos

Answer 16

• defective collagen, most often types I or V

Question 17

cause of Alport syndrome

Answer 17

• defective type IV collagen

Question 18

mutation found in Marfan’s

Answer 18

• caused by a defect in fibrillin (fibrillin-1 gene)

Question 19

blotting procedures

Answer 19

• SNoW DRoP
• Southern= DNA
• Northern= RNA
• Western= Protein
• Southwestern=DNA-binding proteins

Question 20

cause and presentation of Prader-Willi syndrome

Answer 20

• paternal allele is not expressed on chromosome 15

- mental retardation, hyperphagia, obesity, hypogonadism, hypotonia

Question 21

cause and presentation of Angelman’s syndrom

Answer 21

• maternal allele is not expressed on chromosome 15

- MR, seizures, ataxia, inappropriate laughter

Question 22

mutation found in achondroplasia

Answer 22

• fibroblast growth factor receptor 3

Question 23

mutation found in ADPKD

Answer 23

• PDK1 on chromosome 16

Question 24

mutation found in familial adenomatous polyposis

Answer 24

• APC gene on chromosome 5

Question 25

mutation found in familial hypercholesterolemia

Answer 25

- defective or absent LDL receptor

Question 26

mutation found in hereditary spherocytosis

Answer 26

- spectrin or ankryin defect

Question 27

mutation found in NF type 1

Answer 27

- long arm of chromosome 17

Question 28

mutation found in NF type 2

Answer 28

- NF2 gene on chromosome 22

Question 29

mutation found in von-Hippel-Lindau disease

Answer 29

- VHL gene (tumor suppressor) on chromosome 3p

Question 30

mutation found in CF

Answer 30

- CFTR gene on chromosome 7

Question 31

mutation found in Duchenne's and Becker's MD

Answer 31

- dystrophin

Question 32

4 diseases associated with trinucleotide repeats

Answer 32

- Fragile X: CGG - Friedreich's ataxia: GAA - Huntington's: CAG - Myotonic dystrophy: CTG

Question 33

mutation found in Cri-du-chat syndrome

Answer 33

- microdeletion of short arm of chromosome 5

Question 34

mutation found in William's syndrome

Answer 34

- microdeletion of long arm of chromosome 7

Question 35

mutation found in DiGeorge's

Answer 35

- 22q11 deletion

Question 36

enzyme deficient in essential fructosuria

Answer 36

- fructokinase

Question 37

enzyme deficient in fructose intolerance

Answer 37

- aldolase B

Question 38

enzyme deficient in classic galactosemia

Answer 38

- galactose-1-phosphate uridyltransferase

Question 39

enzyme deficient in PKU

Answer 39

- phenylalanine hydroylase

Question 40

enzyme deficient in alkaptonuria

Answer 40

- homogentisic acid oxidase

Question 41

enzyme deficient in cystinuria

Answer 41

- defect of renal tubular amino acid transporter (COLA transporter)

Question 42

cause of maple syrup urine disease

Answer 42

- blocked degradation of BCAA

Question 43

cause of Hartnups

Answer 43

- defective neutral amino acid transporter

Question 44

enzyme deficient in hyperchylomicronemia

Answer 44

- lipoprotein lipase deficiency or altered apo-CII

Question 45

enzyme deficient in familial hypercholesterolemia

Answer 45

- absent or decreased LDL receptors

Question 46

cause of hypertriglyceridemia

Answer 46

- hepatic overproduction of VLDL

Question 47

mutation found in abetalipoproteinemia

Answer 47

- microsomal triglyceride transfer protein (MTP) gene which results in decreased B-48 and B-100

Question 48

mutation associated with DM type I

Answer 48

CTLA4

Question 49

mutation associated with DM type II

Answer 49

TCF7L2

Question 50

mutation associated with IBD

Answer 50

IL-23

Question 51

mutation associated with pituitary adenomas

Answer 51

GNAS1

Question 52

mutation associated with autoimmune polyendocrinopathy

Answer 52

AIRE