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FTM test 2 > Genetics > Flashcards

Genetics Flashcards

1
Q

I cell disease

A

Inability to phosphorylate mannose residues (phosphotransferase). Hydrolytic enzymes are not transported to the lysosome leading to macromolecules accumulating as inclusion bodies in the blood

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2
Q

Scurvy

A

Vitamin C deficiency. Decreased stability and tensile strength of collagen leads to: bleeding gums, hemorrhages and poor wound healing.

Lysl and proyl oxidase uses vitamin C as a cofactor to create hydroxyproline and hydroxylysine.

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3
Q

Ehler-Danlos Syndrome

A

Hereditary defect of enzymes needed for a current collagen synthesis and mutations in the genes encoding for alpha chains.

Type III: vascular form most severe due to lethal arterial rupture. Fragile skin and vascular walls.

Type V: Classic form Hypermobile joints and hyperextensibility of skin

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4
Q

Osteogenesis imperfecta

A

AD mutation in COL1A1 or COL1A2. Usually displacement of glycine in bone collagen which affects the formation and stability of the collagen triple-helix.

Type I mildest (OI Tarda): blue sclera

Type II most severe (OI congenita): death in uterine or soon after birth

Type III and IV are severe, but not as deadly: scoliosis and denial issues

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5
Q

Marfan

A

AD: Defect in fibrillin-1 (scaffolding), elastin is normal.

Long limbs, lens dislocation, arachnodactyly, aortic dilation, pectus excavatum

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6
Q

Immunodeficiency-centromeric instability-facial anomalies syndrome (ICF)

A

AR: Dnmt3b mutation

facial dysmorphism, mental retardation, recurrent/prolonged infections, and variable immune deficiency with a constant decrease of lgA.

Immunodeficiency associated w/ centromere instability of chromosomes 1, 9, and 16

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7
Q

Prader-Willi

A

Chromosome 15

Paternal deletion, maternal imprint. No SNRPN gene. Active UBE3A.

Maternal uniparental disomy

Mental/developmental delay, obese, underdeveloped genitalia

FISH, CGH

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8
Q

Angleman

A

Chromosome 15

Maternal deletion, paternal imprint

No copy of UBE3A, active SNRPN

Paternal uniparental disomy

Happy puppy syndrome, inappropriate laughter, severe intellectual disability, seizures

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9
Q

Rett Syndrome

A

X-linked dominant

Mutation in x-linked MeCP2 (methyl-cytosine binding protein 2)

Lethal in males. Affects mostly females. Normal development until 6-18 months. Then regression phase loss of speech/hand skills. Develop seizures, repetitive hand motions.

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10
Q

Beckwith-Wiedeman Syndrome (BWS)

A

Maternal rearrangement of 11p15, paternal uniparental disomy, abnormal methylation at 11p15

Macroglossia (large tongue), large birth weight, umbilical hernia, microcephaly, ear creases or pits

Increased risk with IVF

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11
Q

Incontinentia Pigmenti

A

X-linked dominant: IKBKG gene mutation. Inhibitor of kappa light polypeptide gene enhancer in B-cells, kinase gamma

Males die in uterine

Variable expressivity due to x inactivation

Rashes and blisters in early life, hyperpigmentation later in life, possible retinal detachment, possible intellectual disabilities

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12
Q

Bloom Syndrome

A

Defect in BLM gene (DNA helicase) required for replication repair and recombination.

Chromosomal instability resulting in chromosomal breaks and sister chromatid exchange. Increased cancer risk

Butterfly facial rash upon sun exposure

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13
Q

Xeroderma Pigmentosum

A

AR and locus heteroginity

Nucleotide excision-repair. Mutations in 9 different NER genes can cause disorder.

Extreme sun sensitivity, skin cancer, neurological abnormalities

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14
Q

Ataxia Telangiectasia

A

AR: defects in ATM (11q22-23), a serine-threonine kinase

ATM detects DNA damage actives cell cycle arrest and DNA repair proteins

Double strand breaks

Affects cerebellum and immune system
Ocular telangiectasia common

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15
Q

Burkitt Lymphoma

A

Activation of MYC via t(8:14)

MYC (proto-oncogene) =TF translocated next to the promoter site of IgH. Always active.

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16
Q

Chronic Myeloid Leukemia (CML)

A

Philadelphia chromosome: t(9:22) creates BCR-ABL hybrid protein resulting in unregulated cytosolic tyrosine kinase

Treated with Imatinib mesylate (Gleevec)
Tyrosine kinase inhibitor

Oncogene

FISH

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17
Q

Li Fraumeni Syndrome

A

Inherited mutation in p53

Greatly increases risk for various cancers ata young age (breast, bone, brain, soft tissue carcinoma)

Tumor suppressor gene

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18
Q

Wilms Tumor

A

Renal cancer

Loss of function in WT1 gene chromosome 11 which encodes for TF controlling cell growth and differentiation

Tumor suppressor gene

19
Q

Retinoblastoma

A

Rb

Tumor suppressor gene

20
Q

BAX

A

Proapoptotic

21
Q

P53

A

cell cycle arrests for DNA repair or apoptosis

22
Q

BCL

A

inhibits BAX

23
Q

Familial Adenomatous Polyposis (FAP)

A

Mutation in APC (Adenomatous Polyposis Coli) gene.

APC encodes for tumor suppressor whose role is to down-regulate growth promoting signals

Chromosome 5

APC = gatekeeper

Colorectal cancer: slow, multiple polyps

24
Q

Hereditary Non-polyposis Colon Cancer (HNPCC)/ Lynch Syndrome

A

Mutations in mismatch repair proteins MSH2 and MLH1 resulting in microsatellite instability (Simple repetitive DNA tandem repeats)

Caretaker genes

Colorectal cancer: few polyps, rapid

Locus heterogeneity

Mismatch is a post-replicative repair mechanism

25
Q

Down syndrome

A

Trisomy 21, 47 chromosomes

Single palmar crease,

Increased maternal age, meiotic nondisjunction during oogenesis meiosis I, Robertsonian translocation, mosaic

26
Q

Edwards Syndrome

A

Trisomy 18

Nondisjunction during oogenesis

Clenched fist, overlapping fingers, rocker bottom feet, small lower jaw

47 chromosomes

27
Q

Patu Syndrome

A

Trisomy 13

Nondisjunction during oogenesis

Polydactyl, cleft lip/palate, microphthalmia (small eyes)

28
Q

Turner Syndrome

A

X0

Nondisjunction during spermatogenesis

Webbed neck, amenorrhea, gonad dysgenesis, can be mosaic if mitotic nondisjunction occurs during embryogenesis, NO BARR BODY

Sex chromosome aneuploidy

45 chromosomes

29
Q

Klinefelter

A

Nondisjunction during meiosis I or II mom/ meiosis I dad

Gynecomastia, female hair distribution, infertility YES BARR BODY

Can be mosaic

Sex chromosome aneuploidy

47 chromosomes XXY

30
Q

Cri-du-chat

A

5p loses genetic material from p15.3 to the terminal

Cat like cry, micrognathia (small jaw), hypertelorism

31
Q

DiGeorge

A

Microdeletion 22

Absent thymus, cleft lip and palate, heart defect

32
Q

Wolf-hirschhorn

A

Deletion on chromosome 4p

Roman helmet , facial anomalies, wide spread eyes, high arched eyebrows,

33
Q

Robertsonian Translocations

A

Occurs between acrocentric chromosomes 13,14,15,21,22

Loss of short arm (p), fusion of long arm (q)

34
Q

Kwashiorkor

A

Deficiency of dietary proteins

Decreased blood albumin, abdominal edema

35
Q

Marasmus

A

Deficiency in carbs, lipids, proteins

Arrest growth, extreme tissue atrophy, emancipation, anemic, can be found in elderly

36
Q

Lesch-Nyhan Syndrome

A

X-linked recessive

Deficienct HGPRT: inability to salvage purine bases, increased degradation, increased PRPP levels leading to de novo synthesis

Increased uric acid, severe mental impairment, SELF MUTILATION, gout

37
Q

ADA Deficiency (SCIDS)

A

Deficiency in adenosine deaminase

DNA not synthesized in T and B cells because of an accumulation of dATP

Normally removes ammonia (deaminates) adenosine to inosine

Immunodeficiency, child morality due to overwhelming infections

38
Q

Purine nucleoside phosphorylase deficiency (PNP)

A

Impairment of T-cell function

Decreased uric acid production and increased purine nucleosides and nucleotides

Removes ribose from inosine to form hypoxanthine

39
Q

Thiopurine methyltransferase (TPMT) deficiency

A

Catalyzes a methylation reaction to inactivate 6-mercaptopurine

The drug (chemotherapy for leukemia) inhibit purine synthesis (can’t make RNA or DNA)

pts w/ this disorder need a reduced dose as they are at increased risk for myelosuppression (low RBC, WBC, and platelets)

40
Q

Orotic Aciduria

A

Pyrimidine biosynthesis: deficient OPRT/OMP (UMP synthase).

Deficiency in Pyrimidines results in decreased RBC forming, DNA synthesis/cell division. (anemia). Improves with uridine. Normal ammonia levels

Urea cycle defect: Hyperammonemia Type II deficiency in ornithine transcarbamoylase. Increased amounts of carbamoyl phosphate that is formed in the mitochondria (urea cycle), diffuses into the cytosol and is used for pyrimidine biosynthesis, causing increased formation of orotic acid and orotic aciduria

41
Q

BRCA 1 and BRCA 2

A

Involved in DNA repair or a apoptosis when DNA can’t be repaired (DSB)

Double strand breaks are repaired by non-homologous end joining (most common) and recombinational repair (less errors, uses homologous chromosomes)

Allelic heterogeneity

Tumor suppressor gene

42
Q

ERBB2

A

Encodes for HER2 a tyrosine receptor

Breast cancer. Over expression of HER2 leads to constitutively active tyrosine kinase

Double minutes extrachromosomal elements

Treated with Herceptin (trastuzumab)

43
Q

ERBB1

A

Encodes for the epidermal growth factor receptor (EGFR)

Point mutations cause constitutive activation of EGFR tyrosine kinase

Lung adenocarcinomas

44
Q

RAS

A

Proto-oncogene

Activated by GTP

Cause phosphorylation cascade that activate cellular proliferation

Inhibited by intrinsic GTPase activity (GTP -> GDP)

Single point mutation at Gly12 or Gln61

FTM test 2 (2 decks)

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