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Unit 2 M2M > Unit 2 Day 6 > Flashcards

Unit 2 Day 6 Flashcards

1
Q

karyotype of turners

A
  • XO
  • loss of second sex chromosome
  • widely spaced nipples, broad chest, underdeveloped ovaries
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2
Q

abnormalities of CVS in TS

A 
Bicuspid Aortic Valve
Coarctation of the aorta
 Systemic Hypertension
Prolonged QTc Syndrome
Partial anomalous pulmonary venous connection
Persistent left SVC
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3
Q

abnormalities of Eye with TS

A

inner canthal folds
ptosis
blue sclera

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4
Q

abnormalities skeletal system with TS

A

cubitus valgus
short 4th metacarpal
short stature

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5
Q

abnormalities of neck with TS

A

webbed neck
low hairline
cystic hygroma

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6
Q

learning abnormalities TS

A

difficulty math
visual spatial skills
low non-verbal scores

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7
Q

other abnormalities TS

A

lymphatics: prenatal =cystic hygroma, newborn is neck webbing
urinary system
loss of hearing/vision
endocrine: hypothyroidism, gonadal dysgenesis

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8
Q

what are the challenges TS patients experience across their lifetime?

A
  • infertility
  • stature
  • sexual development
  • concerns regarding health and aging
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9
Q

what are common pitfalls in disclosure?

A

secret keeping
difficulty communicating infertility diagnosis
perceived negative experiences with physicians

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10
Q

Hb F (alpha2gamma2)

A

birth: 60-90%

>2yrs:

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11
Q

Hb A (alpha2beta2)

A

birth: 10-40%
>2 years: >95%
-most common in adults

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12
Q

HbA2 (alpha2sigma2)

A

birth: 2 yrs:

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13
Q

when do you see sickle cell disease?

A
  • symptoms show 6 months of age since still have HbF.

- at 6 months, spleen doesn’t function well

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14
Q

SB0 thalassemia

A

don’t make any hb

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15
Q

SB+ thalassemia

A

make some hb

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16
Q

Hb S

A

sickle cell

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17
Q

Hb C

A

-amino acid substitution–> lysine for glutamic acid

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18
Q

Hb E

A
  • beta chain substitution
  • gene has been genetically fixed
  • in some SEAsia areas, almost 100% penetrant, combination with thalassemia is increased severity
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19
Q

qualitative hemoglobinopathies

A

Hb S
Hb C
Hb E

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20
Q

quantitative hemoglobinopathies

A 
α thalassemia
β thalassemia
γ thalassemia
Δ thalassemia
delta and gamma can change clinical presentation
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21
Q

hemoglobinopathies

A
  • 15% of Africans are S carriers
  • 7% of SE Asians are E carriers
  • 4-5% of SE Asians and Mediterranean population are beta thal carriers
  • 350,000 babies are born throughout the world each year with major hemoglobin disorders
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22
Q

mutations by region

A 
#1 – Southeast Asia: α, β thalassemia and E
#2 Africa – S, C, α and β thalassemia
#3 West Pacific – α and β thalassemia and E
#4 East Mediterranean – β thalassemia and S
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23
Q

thalassemia

A

reduced rate of 1 or more of global chain synthesis. leads to imbalanced/defective global chain production, damage to RBC and precursors

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24
Q

alpha thalassemia types

A 
α thalassemia major
α thalassemia 3 gene deletion 
α thalassemia 2 gene deletion
α thalassemia 1 gene deletion 
α thalassemia + Hgb Constant Spring
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25
Q

beta thalessemia types

A 
β thalassemia major “Cooley’s anemia”
 β thalassemia intermedia
 β thalassemia trait
SB° thalassemia 
SB+ thalassemia
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26
Q

differences btwn African and Asian alpha thalassemia

A

Africa: haplotypes are different

  • One always have normal allele
  • Always inherit one or two

SE asia, there is incomplete allele
-So there is a chance of getting 2 abnormal alleles

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27
Q

autosomal recessive disorders

A
  • homozygote expression
  • males and females equally affected
  • horizontal inheritance
  • parents=carriers
  • recurrence risk for children is 1/4, unaffected is 2/3
  • frequency is q^2
  • frequency of mutant allele=q
28
Q

frequency of wild type allele

A

p (p+q=1)

29
Q

frequency of normal

A

p^2

30
Q

carrier frequency

A

most of the time q is so small you can approximate p as 1

find q by taking square root of q^2

31
Q

tay sachs carrier frequency

A

1/300 general population
risk: 1/300 x 1/300 x 1/4 =1/360000
if parents are carriers: 1/2 x 1/2= 1/4

32
Q

allelic heterogeneity

A

presence of multiple common mutant alleles of the same gene in a population

33
Q

compound heterozygote

A

individual who carries 2 diff mutant alleles of the same gene

34
Q

phenylketonuria phenotypes

A

PKU

  • high phenylalanine love in the blood
  • high levels metabolites in urine
  • hyperactivity and epilepsy
  • metal retardation, microcephaly
  • babies affected by this
35
Q

PKU defects in PAH

A
  • high allelic heterogeneity. 7 alleles account for 2/3 of all PAH mutations in European populations. 6 alleles account for 80% of PAH mutations in Asian populations
  • compound heterozigysity
  • varied phenotype severity
36
Q

PKU newborn screening

A
  • done with tandem mass spectrometry
  • sorts molecules by size, weight, quantity
  • multiple molecules measured simultaneously
  • timing is critical, baby carries enzymes from mom, once digesting food it builds up, test late enough but not too late
37
Q

PKU treatment

A
  • low phenylalanine diet
  • BH4 supplementation
  • neutral amino acid supplementation, enzyme replacement therapy, gene therapy
38
Q

PKU maternal effect

A
  • off low Phe diet in pregnancy
  • increases risk of miscarriage
  • malformations/retardation
39
Q

alpha 1 antitrypsin deficiency (ATD)

A
  • more common in people with northern European ancestry
  • disease is 1/2500, carrier frequency ~4%
  • underdiagnosed
  • risk of emphysema, liver cirrhosis and cancer
  • more severe symptoms in smoker
  • caused by mutations in alpha 1-AT gene
  • made in liver, transported to lungs in blood
40
Q

ATD defects

A
  • deficiency in ATD, protease inhibitor
  • SERPINA 1=suicide substrate of serine protease elastase
  • imbalance elastase and SERPINA 1
  • cycles of elastase release and lung damage in ATD
  • eventually lung loses elasticity
41
Q

elastase

A

released by activated neutrophils at airway, destroy elastin in connective tissues

42
Q

ATD Z allele

A
  • most common mutant allele
  • Z/Z phenotype have ~15% normal SERAPINA level
  • make protein that isn’t folded properly and tends to accumulate in ER of liver cells
43
Q

ATD S allele

A

makes unstable SERPINA1 protein

-S/S genotype has 50/60% normal level

44
Q

ATD M allele

A

encode functional proteins (wild type)

45
Q

ATD treatment

A

current treatments:

  • bronchodialators/inhaled steroids
  • vaccinations
  • pulmonary rehab
  • lung transpant
  • treatments in development: enzyme replacement therapy, gene therapy, release misfolded AAT from liver to blood w/ chemicals
46
Q

Tay-Sachs

A
  • genetic fetal disorder
  • progressive destruction CNS
  • T-S babies die by 2-4 years
  • first signs: muscle response
47
Q

tay-sachs biochemical defects

A
  • lysosomal storage defects, too much Gm2 builds up
  • synthesized in neurons and cell membrane
  • unable to degrade it
  • Hexosaminidase A consists of alpha/beta subunits (encoded HEXA/B genes)
  • T-S have mutations in HEXA gene
  • hex b causes sandhoff disease
48
Q

hemoglobin as tetramer

A
  • 2 alpha beta hetrodimers
  • lots of salt bridges
  • heme group has iron in center, linked to histidine
49
Q

human global gene clusters

A
  • beta locus codes for beta and beta genes
  • switch from beta to alpha, switch from gamma to alpha
  • majority of adult hemoglobin is alpha 2 beta 2
50
Q

globin switching

A
  • change of expression patterns during development
  • theta to epsillon to beta
  • alpha has one switch, stays on
  • beta has 2 switches, controlled around time of birth
  • gamma plus beta is similar to alpha
51
Q

Locus control region

A
  • regulates globin transcription

- each gene has own promoters 20-40kb upstream

52
Q

genetic disorders of hemoglobin

A
  • structural variants (synthesize normally, different globin)
  • thalassemeias (low to zero synthesis of chain)
  • defective globin switching (persistance fetal hemoglobin)
53
Q

sickle cell disease: HbSS

A

single gene disease
point mutation-codon 6, exon 1 of beta global
glutamate –>valine
can’t deform

54
Q

hemoglobin C disease: HbCC

A
  • affects same codon as HbSS
  • glutamate–>lysine
  • first codon (sickle is second)
  • form crystals
  • altered solubility
55
Q

DNA diagnosis sickle cell

A
  • restriction enzyme Mst 2 recognizes code
  • sickle cell changes A to T, destroys site
  • larger chunk
56
Q

Speed of Hemoglobin electrophoresis

A
  • Wt is HbA
  • S is slower
  • C is slowest (+ charge)
57
Q

polycythemia (Hb Kempsey)

A
  • higher O2 affinity
  • less O2 to tissues
  • overproduction RBC
58
Q

cyanosis (Hb kansas)

A
  • lower Hb-O2 affinity
  • lower O2, level RBC
  • bluish skin
59
Q

alpha thalassemia

A
  • low/zero alpha globulin, excess beta and gamma
  • fetal/postnatal defects
  • deletion alpha globin gene
  • only when you go below 50% are going to have problems
  • h disease=beta 4
  • some areas SEAsia mutant is less frequent, baby dies b/c gamma 4 is not sufficient
60
Q

beta thalassemia

A
  • low/zero beta globulin, excess alpha and precipitates
  • postnatal defects
  • point mutations in beta globin
  • caused by deletions in LCR region of beta gene cluster
61
Q

hemolysis

A

the rupture or destruction of red blood cells.

62
Q

microcytosis

A

red blood cells are unusually small as measured by their mean corpuscular volume

63
Q

hypochromia

A

anemia in which the red blood cells (erythrocytes) are paler than normal

64
Q

alpha thalassemia

A

SEAsia: alpha thal 1
–/– hydrops fetalis
alpha -/– HbH disease
aa/– mild anemia

Africa, Med, Asia: alpha thal 2
a-/a- mild anemia
alpha thalessemia traits

65
Q

beta thalassemias

A
  • beta locus, affects beta globin
  • not turned on till after birth
  • switch from gamma to beta occurs gradually

major-need treatment/transfusion
minor-little/no symptoms
beta + some expression but not enough
beta 0 - no detectable beta

66
Q

HPFH mechanisms and implications

A
  • large deletions or promoter mutations
  • large deletions bring enhancers downstream closer to beta locus–> gamma expressed after birth
  • promoter mutations shut off expression of gamma
  • less beta, substitute expression of beta
  • try to keep gamma from shutting off: prevent from happening by using BCA 1, gene silencing w/ RNA and mRNA, 2 micro RNA present on 13

Unit 2 M2M (8 decks)

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