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Genetic Disorders Flashcards

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1
Q

Hurler Syndrome

Type, Gene, Symptoms, Rx

A

Autosomal Recessive

Gene: alpha-L-Iduronidase

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2
Q

Tay- Sachs:

type
What gene?
Build up of what?
Mutation Type and Result?

A

Autosomal Recessive

Gene: HexA

Build up of GM2 gangliosides leading to neuron damage

Mutation: 4 base insertion causing frameshift mutation. Premature stop codon and truncated protein

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3
Q

Cystic fibrosis

Type
Gene
Mutation type
Result

A

Autosomal Recessive

gene: CFTR

Mutation type: 1 amino acid lost, but in-frame mutation

Result: prevents CFTR chloride channel. Results in thick mucus sections because water isn’t attracted.

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4
Q

Sickle Cell Disease

Type

Mutation type

A

Autosomal Recessive

Mutation: wrong amino acid, (A to T)

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5
Q

Beta-Thalassemia

Type

Mutation type

A

Autosomal recessive

Point mutations decreasing production of beta globin (hemoglobin)

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6
Q

Hereditary hemochromatosis

Type

Gene

Mutation type

Whos affected

A

Autosomal Recessive

Gene: HFE (high iron)

Mutation: single missense resulting in iron overload

Who is affected? adult males more commonly affected

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7
Q

Huntington disease

Type:
Gene:

A

Autosomal dominant

Gene: HD, trinucleotide repeat expansion

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8
Q

Achondroplasia

Type:
Gene:

A

Autosomal dominant

Gene: FGFR-3, glycine to arginine missense, gain of function

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9
Q

Neurofibromatosis Type 1

Type
Gene

A

Type: autosomal dominant

Gene: NF1, nonsense point mutation resulting in shortened protein

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10
Q

Marfan Syndrome

Type
Gene

A

Autosomal dominant

Gene: FBN1, elastic fibers in connective tissue

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11
Q

Lesch - Nyhan Syndrome

Type
Gene

A

X-linked recessive

Gene: HGPRT - involved in purine recycling. Deficient HGPRT results in overproduction of uric acid

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12
Q

Duchenne muscular dystrophy

Type
Gene
mutation type

A

X-linked recessive

Gene: dystrophin (muscle fibers, largest human gene)

Mutation type: deletion leading to frameshift.

Milder cases have mutations without frame shift (becker) and protein is partially active

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13
Q

Hemophilia B

Type
males or females?
effect
mutation

A

X linked recessive

Affects males, females have second working X chromosome

Effect: deficiency of factor IX

Mutation: point mutation in promotor region of gene, A to G transition alters transcription factor of factor IX gene

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14
Q

Gowers sign

A

results from weakness of lower limbs

Use arms to “climb” up the legs to elevate the torso.

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15
Q

Rett syndrome

Type
Gene
variation of Sx
Male or female

A

X linked dominant

Gene: MeCP2

Variation in females due to skewed x-inactivation patterns

Generally not transmitted through families

Lethal in males

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16
Q

Fragile X Syndrome

Type
Gene
male or female

A

X linked dominant

Gene: FMR1, CGG repeat expansion in promotor region

More severe in males

Anticipation observed in later generations due to trinucleotide repeat expansion when female carriers pass the trait.

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17
Q

Langer mesomelic dysplasia and Leri-Weill dyschondrosteosis

Type
Mutation

A

Y chromosome disorder

mutation in pseudoautosomal region of SHOX gene

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18
Q

Swyer syndrome

Type
effect

A

Y chromosome, SRY gene disorder

Effect: genotypic male develops as a female

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19
Q

46 XX testicular disorder of development

Type
effect

A

Y chromosome disorder, SRY translocation onto X chromosome

Effect: individuals develop as male, with similar sx to kinefelter

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20
Q

Mitochondrial diseases

A 
CEPO
Kearns-Sayre
Leigh
LHON
MERRF
MELAS
Person Syndrome
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21
Q

Phenylketonuria (PKU)

Type
Gene
Sign
Treatment

A

Autosomal recessive

Gene: PAH

Signs; phenylalanine and phenylketones in blood. Phenylketones in urine

Treatment: restrict dietary phenylalanine. if caught early, neurological damange can be mitigated

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22
Q

PKU: causes of intellectual disability

A

high levels of phenylalanine and phenylketones directly toxic to brain

Excess phenylalanine saturates lare neutral amino acid transporter at BBB, leading to excess of phenylalanine in brain and preventing other AAs from entering

Failure to produce adequate dopamine and epi due to lack of tyrosine

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23
Q

Origin of Trisomy 21

A

95% of cases due to mother’s nondisjunction of chromosome 21

5% due to robertsonian translocation

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24
Q

Trisomy 18 (Edward Syndrome)

Origin
Sxs

A

Nondisjunction of chromosome 18 in mother

Sx: intellectual disability
low weight
diaphragmatic hernia
heart defects
small eyes, mouth, receding jaw
kidney defects
clenched fists
rocker bottom feet
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25
trisomy 13 (Patau syndrome) Origin Sx
Origin: 95% nondisjunction in mother. 5% Robertsonian translocation ``` Sx: intellectual disability Microcephaly, holoprosencephaly postaxial polydactyly cleft lip/palate small eyes, large triangluar nose deafness ```
26
Turner syndrome Cause Sx Treatment
45, X Cause: one X chromosome, so only 1 copy of PAR1 and PAR2 genes Sx: short stature, learning disabilities, braod neck, visual impairments, kidney abnormalities, ovarian dysgenesis and lack of secondary sexual characteristics Treatment: growth hormone and estrogen therapy
27
Klinefelter Syndrome Origin Sx Treatment
47, XXY Sx: often SUBTLE Treatment: testosterone therapy, speech therapy, physical therapy
28
Exons
coding regions that contain DNA sequence that translates to the final protein product
29
Introns
non-coding regions that contain regulatory information and can be removed by splicing
30
Molecular fingerprint
uses polymorphisms to identify an individual. identifies using the number of repeats in a sequence. CODIS is used by the FBI to search a set of 15 VNTR loci Everyone has 2 sets of chromosomes with their own repeat polymorphism pattern
31
STRP
2-5 bp
32
VNTR
14-500 bp
33
CNV
2 million bp
34
Paternity testing
uses VNTR analysis and compares bands of potential fathers to child. If no bands are shared, the individual is not the father.
35
Nonsense mutation
introduces new stop codon
36
silent sense mutation
base change that doesn't alter the amino acid
37
missense mutation
wrong amino acid
38
Frameshift mutations
1-2 bp deleted or added (or multiples) cause codons to be read in the wrong frame.
39
In-frame mutation
3bp added or deleted, extra amino acid is inserted/deleted but remaining codons are read correctly
40
DNA 3' and 5' ends
3' OH group, 5' terminal phosphate.
41
Techniques for genotyping or sequencing DNA
PCR, southern blot, cloning Detects and quantitates specific genes
42
Measures gene expression
northern blot, microarray, qRT-PCR, Next Gen sequencing
43
Measures protein expression
Western blot, ELISA detects presence and relative quantity of protein
44
4 steps of PCR
denature, anneal, elongate, repeat for 20-35 cycles
45
Principle of independent assortment
an allele transmitted at one locus has no influence on which allele is transmitted at another locus
46
Gene frequency
how often a particular gene sequence (allele) occurs in a population
47
genotype frequency
how often a given genotype occurs in a population
48
Occurrence risk
risk of producing an affected child when no children have yet been produced
49
Recurrence risk
risk of producing an affected child when one or more children with the disease have been produced
50
Autosomal Dominant Diseases
Huntingtons Disease (HD), Achondroplasia (FGFR-3) Neurofibromatosis type 1 (NF1) Marfan Syndrome (FBN-1) Familial hypercholesterolemia (LDL receptor gene)
51
6 Characteristics of autosomal recessive inheritance
1/4 of offspring btwn heterozygous affected if parents are carriers, multiple affected children likely sometimes no family hx of disease carrier individuals are present in skipped generations males and females equally likely cosanguinity present
52
Hardy Weinberg Principle
(p+q)^2 = p^2 + 2pq + q^2 = 1 (p+q)^2 = gene frequency p^2 = homozygous dominant frequency q^2 = homozygous recessive frequency 2pq = heterozygous frequency
53
Find 2pq (heterozygous frequency)
q^2 = tt frequency. find this (given) square root it (you end with q) subtract q from 1 (you end with p) calculate 2pq
54
Principle of segregation
genes remain intact and distinct in next generation, they are not blended.
55
Lysosomal storage disorders
Hurler syndrome, Tay-Sachs
56
Autosomal recessive diseases
Hurler syndrom (a-L-iduronidase, glycosaminoglycan) Tay Sachs (HexA, GM2 gangliosides) Cystic Fibrosis (CFTR) Sickle Cell (B-globin gene B-Thalassemia (B-globin) Hereditary hemochromatosis (HFE)
57
Sporadic occurance
de-novo mutation achondroplasia, NF1
58
Germline mosiacism
Germline consists of more than one distinct population of cells. osteogenesis imperfecta
59
Delayed age of onset
diseasae doesn't manifest until adulthood huntington disease, hemochromatosis
60
Reduced penetrance
not everybody carrying the genotype will express the associated phenotype Retinoblastoma (Rb, 90% penetrance)
61
Variable Expression
affects severity of disease independent of penetrance NF-1
62
Pleiotropy
exerts its effects on multiple aspects of physiology or anatomy Cystic fibrosis, Marfan Syndrome
63
Heterogeneity
mutations at different gene loci can produce the same disease phenotype Osteogenesis imperfecta
64
Genomic Imprinting
paternal and maternal chromosomes contribute different amounts of gene product Prader willi (from father), angelman (from mother)
65
Anticipation
displays an earlier age of onset/more severe expression in more recent generations Myotonic dystrophy, fragile X, huntington
66
Cosanguinity
mating between related individuals Rare recessive diseases
67
X-Activation, incompletion
15% of genes on X chromosome remain active XIST gene PAR1/PAR2 genes behave like autosomes, their products are found on x and y chromosomes
68
replicative segregation in mtDNA
random distribution of mtDNA among daughter mitochondria, and random distribution of mitochondria between daughter cells
69
Homoplasmy and heteroplasmy
homoplasmy = daughter cell received pure population of mito, all with normal or all with mutated DNA Heteroplasmy = daughter cell received mixed population of mitrochondria, some with and some without mutated mtDNA
70
polygenic model
trait in which variation thought to be a combined effect of multiple genes additive polygenic model states the number of phenotypic classes increases as the number of genes controlling a trait increases. Applied to quantitative traits
71
Threshold model
applied to qualitative traits, all-or-nothing traits. Must meet a threshold of liability to develop disease Threshold may be different in different populations
72
Pyloric stenosis
Threshold model example males more effected sx: recurrent vomiting, dehydration, electrolyte imbalance.
73
Factors affecting recurrence risk
of affected family members degree of relationship to proband increases if proband is of less commonly affected sex severity of disease in proband
74
Twin types
monozygotic = identical twins Dizygotic = fraternal twins
75
heritability (h)
the proportion of variation in a disease trait that can be attributed to genes h = 2(Cmz - Cdz)
76
amniocentesis
optimal time: 15-20 weeks tests: cytogenic analysis, DNA testing, Fetal a-fetoprotein (AFP) High AFP = high risk of neural tube disorders Low AFP = risk of trisomies
77
Chorionic Villus Sampling
optimal time: 10-12 weeks sample collected: fetal trophoblastic tissue tests: cytogenic analysis, DNA testing Conditions: chromosomal abnormalities
78
Ultrasonography
Optimal time: 16-18 weeks Visualization of fetus for structural abnormalities
79
Maternal serum screening and Nuchal Translucency
optimal time: 11-14 weeks Sample collected: maternal serum + ultrasounds Tests: AFP in mothers serum, increased nuchal translucency suggests risk of chromosomal anomalies Conditions: trisomies and neural tube disorders High AFP = neural tube Low AFP = trisomies
80
Triple Screen
combines three proteins: maternal AFP, hCG and estriol Accurate at 16-18 weeks concerns with false positives
81
Cell-free fetal DNA testing
measures fetal DNA shed into mothers blood during pregnancy simple blood draw for mom Results should be confirmed with another method Tests for trisomies, aberrant numbers of sex chromosomes, sex of baby
82
acrocentric chromosomes
13, 14, 15, 21, 22 Involved in Robertsonian translocations
83
Cell cycle beginning
mitogen binds to receptor Phosphorylation cascade via Ras MAPK activated, increases synthesis of MYC MYC transcription factor increases expression of cyclin D.
84
Cyclin-CDK complexes in cell cycle
G1 early - cyclin D-CDK4/6 G1 late - Cyclin E- CDK2 G1/S .- Cyclin A-CDK2 S/G2 - Cyclin A-CDK1 M - Cyclin B-CDK1 "Do Enter After the Bell"
85
Antimetabolites
Methotrexate S phase of cell cycle inhibits synthesis of dTMP and purines thereby disrupting DNA production
86
Mitotic inhibitors
Paclitaxel G2/M phase bind to microtubules, arrests mitosis in metaphase induces apoptosis by blocking function of apoptosis inhibitor Bcl-2
87
Anti-tumor antibiotics
Doxorubicin, anthracycline, daunorubicin Intercalating into DNA
88
Alkylating agents
Cisplatin, carboplatin interphase forms covalent interstrand and intrastrand crosslink with purine bases interferes w/ DNA repair, synthesis and transcription
89
Immunotherapy
Herceptin/Trastuzumab binds to extracellular domain of HER2 that has RTK activity, blocking downstream signalling reduces number of cells in S phase
90
inhibition of cancer promoting proteins
Imatinib/Gleevac a signal transduction inhibitor via RTK
91
Inhibiting angiogenesis
Avastin Inhibitor of VEGF receptor.

Biochem (9 decks)

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