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Clinical Science > Lecture 4: Mendelian Diseases Part Two > Flashcards

Lecture 4: Mendelian Diseases Part Two Flashcards

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1
Q

What mutation is hemophilia caused by?

A

F8 or F9 on X chromosome

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2
Q

Hemophilia A is a disorder of what gene?

A

factor 8 gene

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3
Q

Hemophilia B is a disorder of what gene?

A

factor 9 gene

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4
Q

Which hemophilia is considered classis hemophilia and is most common?

A

Hemophilia A; factor 8 gene

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5
Q

How is hemophilia A and B inherited?

A

X-linked recessive

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6
Q

How common is it that patients do not have family history and have a de novo mutation of hemophilia?

A

1/3 of hemophilia patients have a de novo mutation

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7
Q

What is a manifestation of hemophilia in newborns?

A

intracranial hemorrhage with seizures; this is increased with the use of forceps or vacuum in delivery

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8
Q

When do the majority of children with sever hemophilia become symptomatic?

A

within the first two years of life and are typically diagnosed by age 6

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9
Q

What are some manifestations of hemophilia?

A

bruising, hemarthrosis (bleeding in the joint tissue), epistaxis, hematuria, blood in the stool

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10
Q

What is von willebrand factor?

A

large glycoprotein; involved in platelet adhesion to the subendothelium; receptors in platelets bind to the VWF; acts as a carrier for factor 8 in circulation

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11
Q

What is the most common inherited bleeding disorder?

A

von willebrand disease

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12
Q

What is characteristic about Von Willebrand Disease?

A

has low factor 8 activity with missing or dysfunctional VWF activity

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13
Q

How is von willebrand disease inherited?

A

mostly autosomal dominant; some autosomal recessive

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14
Q

What is type 1 von willebrand disease

A

has low VWF; most common; mostly autosomal dominant

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15
Q

What is type 2 von willebrand disease?

A

normal levels of VWF but the VWF does not work correctly

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16
Q

What is type 3 von willebrand disease?

A

has little or no VWF; the least common; causes the most severe symptoms; usually autosomal recessive; has mutations that result in an abnormally short nonfunctional von willebrand factor

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17
Q

On which chromosome is VWF gene located?

A

chromosome 12

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18
Q

How is hemophilia C inherited?

A

autosomal recessive pattern

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19
Q

How many oxygen’s can each iron in a heme group bind?

A

one oxygen

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20
Q

In what ancestry is sickle cell anemia more common?

A

sub-Saharan and Africa

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21
Q

What is normal hemoglobin comprised of?

A

two alpha polypeptide chains and two beta polypeptide chains

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22
Q

What is the difference in normal hemoglobin and sickle cell hemoglobin?

A

there is a single substitution at the 6th codon of the beta hemoglobin chain that causes the amino acid glutamic acid to be replaced with valine

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23
Q

What are the distinguishable characteristics of HbS?

A

sickle cells form long inflexible chains and is not very pliable

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24
Q

How is sickle cell anemia transmitted?

A

autosomal recessive pattern

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25
Q

Why does sickle cell trait protect against malaria?

A

protective affect occurs because sickled hemoglobin is a stronger inducer of heme-oxygenase 1; this enzyme has been shown to protect host from cerebral malaria

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26
Q

What are some manifestations of sickle cell anemia?

A

related to hemolysis and vaso-occlusion; failure to thrive, anemia, splenomegaly, infections, swelling of extremities, jaundice, cholelithiasis, stroke, chronic anemia, acute chest syndrome, renal necrosis, leg ulcers, priaprism, vision loss

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27
Q

What does lipid monitoring typically include?

A

total cholesterol, HDL, triglycerides, LDL

28
Q

What is the gene and chromosome identified with familial hypercholesterolemia?

A

LDR gene on chromosome 19

29
Q

What is LDR gene?

A

encodes a protein for the low density lipoprotein receptor… LDL typically functions as the carrier for cholesterol in the blood; LDL receptors regulate total cholesterol by reducing LDL

30
Q

What happened to LDL receptors in familial hypercholesterolemia?

A

in a defective LDLR gene the receptors are either defective of absent leading to an increase in LDL in circulation

31
Q

Which is more common for the LDLR gene, heterozygous form or homozygous form?

A

homozygous form is rare and consists on atherosclerosis of child having serum cholesterol 8X normal; heterozygous form is more common having LDL 2-3 X normal

32
Q

What are some manifestations of familial hypercholesterolemia?

A

CHD from atherosclerosis, tendon xanthomas (fatty deposits on the skin), xanthelasma around eyes,

33
Q

When should a person be screened for FH?

A

if a family member presents with FH, plasma cholesterol level in adult is > 310 or in a child is > 230, premature CHD or sudden cardiac death, or tendon xanthomas

34
Q

How is marfan syndrome inherited?

A

in an autosomal dominant pattern

35
Q

What is the mutation involved in marfan syndrome?

A

fibrillin-1 gene (FBN1) on chromosome 15

36
Q

What percent of cases of marfan syndrome are de novo?

A

25%

37
Q

What is Fibrillin-1?

A

encodes for glycoprotein fibrillin which is the principle component of the microfibril and therefore part of the structure of collagen

38
Q

Where are microfibrils particularly abundant?

A

in aorta, periosteum, alveolar walls, and skin

39
Q

what is the most concerning manifestation in marfan syndrome?

A

aortic dilatation (aortic root disease) as the major cause of morbidity and mortality in marfan’s

40
Q

What is the effect of the mutation on Fibrillin-1 in Marfan’s?

A

patients do not have normal functioning fibrillin which causes the connective tissue to be overly elastic; there is also weakening in the connective tissues

41
Q

What are the cardiac manifestations of marfan’s syndrome?

A

aortic root disease, aortic aneurysm, aortic regurgitation, aortic dissection, mitral valve prolapse

42
Q

What are the skeletal manifestations associated with Marfan’s syndrome?

A

excess linear bone growth, tall with long arms, arachnodactyl (spider fingers), and dolichostenomelia (arm span is greater than body height), positive wrist sign, positive thumb sign, scoliosis, kyphosis

43
Q

What are the two different manifestations that have to do with the chest in marfan’s?

A

pectus carinatum- funnel chest

pectus excavatum- pigeon chest

44
Q

What are the ocular manifestations associated with marfan’s syndrome?

A

ectopia lentis- dislocated lens

45
Q

What is typically used to diagnose marfan’s syndrome?

A

genetic testing is not always needed and Ghent criteria can be used

46
Q

What is an aortic aneurysm?

A

widening or bulging of the wall of the aorta; defined as having > 50% increase in the diameter for that portion of the aorta

47
Q

What are risk factors for aortic aneurysms?

A

genetic defects such as marfan’s, also smoking, hypertension, and hypercholesterolemia

48
Q

What is an aortic dissection?

A

a tear forms in the inside layer of the aorta and blood begins to fill between the layers; blood fills in the false lumin -> can lead to massive hemorrhage

49
Q

What are some symptoms that can present with an aortic aneurysm?

A

chest pain, upper back and left shoulder pain, hypotension; but most patients that have aneurysms are asymptomatic

50
Q

What are the four P’s in the clinical presentation of an aortic aneurysm or dissection?

A

Pallor, Pulselessness, Parasthesias, and Paralysis

51
Q

How is familial thoracic aortic aneurysms inherited?

A

autosomal dominant inheritance

52
Q

How many genes have been identified for involvement in FTAA?

A

4 genes on 4 different chromosomes

53
Q

What is the difference between patients with FTAA and Marfan Syndrome?

A

in FTAA patients present at a much later age than patients with Marfan Syndrome

54
Q

What is important to remember with genetic testing in FTAA?

A

genetic testing is available for all 4 genes; all first degree relatives should be screened; knowledge prior to pregnancy is important due to the high-risk of dissection and rupture in pregnant women with this condition

55
Q

What are the different types of cardiomyopathies?

A

dilated cardiomyopathy, hypertrophic cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic cardiomyopathy

56
Q

What is hypertrophic cardiomyopathy?

A

the myocardium becomes thickened; especially in the left ventricle

57
Q

What is restrictive cardiomyopathy?

A

walls become stiff and rigid but not thick; usually because of replacement of normal myocardium by scar tissue

58
Q

What is arrhythmogenic cardiomyopathy?

A

right ventricular myocardium replaced with scar tissue

59
Q

what are two of the most common hereditary cardiomyopathies?

A 
hypertrophic cardiomyopathy (HCM)-disorder of the left ventricle
arrhythmogenic cardiomyopathy (ARVD/C)- disorder of the right ventricle
60
Q

How is hypertrophic cardiomyopathy most commonly inherited?

A

in an autosomal dominant pattern

61
Q

What are the mutations involved in HCM? (hypertrophic cardiomyopathy)

A

12 or more genes linked to over 1400 mutations; the mutations involve coding for the tick or thin filaments of the sarcomere; sometimes called disease of the sarcomere

62
Q

What are some manifestations of HCM?

A

left ventricular hypertrophy, impaired left ventricular contractility, dyspnea on exertion, palpitation, chest pain, syncope

63
Q

What is arrhythmogenic right ventricular dysplasia/ cardiomyopathy characterized by?

A

fibro fatty replacement of right ventricle myocardium and myocardial thinning

64
Q

What are the clinical manifestations of ARVD/C?

A

arrhythmias, palpitations, chest pain, syncope

65
Q

How many genes are known to be associated with ARVD/C?

A

8!

Clinical Science (15 decks)

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