Genetics - Hacia

Question 1

Cytogenetics: What are methods of viewing?

Answer 1

FISH - fluorescent in situ hybridizaion allows viewing of DNA segments SKY - Spectral karyotyping -each chromosome labeled with dif dye array CGH -doesn’t require living cells. uses short DNA probes

Question 2

Sex chromosome abnormalities

Answer 2

Turner - 45X (found in fetal tissue from miscarriages) Klinefelter - 47 XXY Triple X -47 XXX XYY -47 XYY

Question 3

Common autosomal chromsomal abnormalities

Answer 3

Down syndrome - trisomy 21 Edwards syndrome - trisomy 18 (eddie walking leash ) Patua syndrome -trisomy 13 (spitting after eating lime)

Question 4

Diseases from autosomal deletions:

Answer 4

Cri du chat -deletion of chrom 5 arm

Question 5

diseases from contiguous gene deletion

Answer 5

Small deleted genomic region, contiguous genes. Smith-Magenis -chrom 17 DiGeorge -chrom 22

Question 6

Genetic mosaicism

Answer 6

cells within person with different genetic makeup ex: nondisjunction during mitosis in development

Question 7

Irinotecan

Answer 7

Toposiomerase inhibitor. Treat colorectal cancer. (Irene running the tecan, overlooking topography of US)

Question 8

Oxaliplatin

Answer 8

induces DNA damage. Treat testicular cancer. (Ox destroying DNA on first plate)

Question 9

5-fluorouracil

Answer 9

antimetabolite. interferes with nucleotide pool.

Question 10

Telomere disease

Answer 10

Dyskeratosis congenita. Defect in genes for repair and protection of teloeres.

Question 11

Direct Repair disease

Answer 11

MGMT. repairs O6methyl guanine lesions. Transfers alkyl group at O6 to cysteine residue. MGMT becomes inactivated. loss of MGMT assoc with increase cancer. Tumors related to MGMT deficiency may respond to certain therapies.

Question 12

Base excision repair disease

Answer 12

FAP2 – familial adenomatous polyposis 2 – risk of colon cancer –mutation in MYH gene

Question 13

Nucleotide excision repair disease

Answer 13

xeroderma pigmentosa and Cockayne syndrome

Question 14

mismatch repair disease

Answer 14

• Lynch syndrome- hereditary non-polyposis colorectal cancer HNPCC • Sporadic microsatellite instability colorectal cancer (MSI) – know how to interpret PCR. Microsatellite seq are repetitive dna seq. if mismatch repair defective, ends up with alleles of difference sizes

Question 15

fanconi anemia

Answer 15

autosomal recessive disorder -mutations in DNA repair genes

Question 16

missense mutation

Answer 16

alters animo acid identity. eg. CFTR c.1652G>A. p.G551D or p.Gly551Asp

Question 17

nonsense

Answer 17

converts codon to a stop codon. CFTR cDNA: c.1624G>T Protein: p.G542X or p.Gly542X nonsense mediated decray- destroys mRNAs with premature stop codon

Question 18

frameshift mutation

Answer 18

insertion or deletion of base pairs, shifts frame and produces premature stop codon. Nonsense mediated decray can degrade mRNA. cDNA: c.3659delC Protein: p.Thr1220LysfsX8 or p.T1220KfsX8

Question 19

in frame deletion

Answer 19

los of one or more amino acids. open reading frame the same. Nucleotide: c.1521_1523delCTT Protein: p.deltaF508 or p.Phe508del

Question 20

splice junction mutation

Answer 20

alters sequence identifying site of splicing of intron Nucleotide: 1585-1G>A + or - to designate intron nucleotide

Question 21

What causes Rett syndrome?

Answer 21

X linked dominant disorder. Males generally not live born. Some males have somatic mosaicism. Caused by MECP2 (methylCpG-binding protein 2) mutations. Only known mutation that causes autism.

Question 22

Why is BRCA1 and 2 autosomal dominant genes when one has back up normal copy?

Answer 22

Two hit hypothesis: somatic inactivation of backup normal copy in cell along with the inherited mutation.

Question 23

What disease is caused by CAG triplet repeats in the HTT gene (expansion of polyglutamine) ?

Answer 23

Huntington disease. Severe neurodegenerative disorder. With genetic anticipation-earlier onset in succeeding generations.

Question 24

What are examples of autosomal recessive disease?

Answer 24

cystic fibrosis, peroxisome biogenesis disorders, Gaucher disease (lysosomal storage disease)

Question 25

What are examples of x-linked recessive disease?

Answer 25

Duchenne & Becker Muscular Dystrophy Hemophilia

Question 26

What are peroxisome biogenesis disorders illustrative of?

Answer 26

penetrance- fraction of indivs with a genotype with disease and has symptoms of the disease. Locus heterogeneity- disease or trait caused by mutations at different loci on genes allelic heterogeneity-different mutations at same locus cause same phenotype

compound heterozygous - mutants in the same gene but different inactivating mutations

Question 27

What inheritance pattern?

Answer 27

Autosomal recessive

Question 28

Answer 28

autosomal dominant

Question 29

Answer 29

x linked dominant

Question 30

Answer 30

x linked recessive