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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
Why does sickle cell trait protect against malaria?
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
26
What are some manifestations of sickle cell anemia?
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
27
What does lipid monitoring typically include?
total cholesterol, HDL, triglycerides, LDL
28
What is the gene and chromosome identified with familial hypercholesterolemia?
LDR gene on chromosome 19
29
What is LDR gene?
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
What happened to LDL receptors in familial hypercholesterolemia?
in a defective LDLR gene the receptors are either defective of absent leading to an increase in LDL in circulation
31
Which is more common for the LDLR gene, heterozygous form or homozygous form?
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
What are some manifestations of familial hypercholesterolemia?
CHD from atherosclerosis, tendon xanthomas (fatty deposits on the skin), xanthelasma around eyes,
33
When should a person be screened for FH?
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
How is marfan syndrome inherited?
in an autosomal dominant pattern
35
What is the mutation involved in marfan syndrome?
fibrillin-1 gene (FBN1) on chromosome 15
36
What percent of cases of marfan syndrome are de novo?
25%
37
What is Fibrillin-1?
encodes for glycoprotein fibrillin which is the principle component of the microfibril and therefore part of the structure of collagen
38
Where are microfibrils particularly abundant?
in aorta, periosteum, alveolar walls, and skin
39
what is the most concerning manifestation in marfan syndrome?
aortic dilatation (aortic root disease) as the major cause of morbidity and mortality in marfan's
40
What is the effect of the mutation on Fibrillin-1 in Marfan's?
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
What are the cardiac manifestations of marfan's syndrome?
aortic root disease, aortic aneurysm, aortic regurgitation, aortic dissection, mitral valve prolapse
42
What are the skeletal manifestations associated with Marfan's syndrome?
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
What are the two different manifestations that have to do with the chest in marfan's?
pectus carinatum- funnel chest | pectus excavatum- pigeon chest
44
What are the ocular manifestations associated with marfan's syndrome?
ectopia lentis- dislocated lens
45
What is typically used to diagnose marfan's syndrome?
genetic testing is not always needed and Ghent criteria can be used
46
What is an aortic aneurysm?
widening or bulging of the wall of the aorta; defined as having > 50% increase in the diameter for that portion of the aorta
47
What are risk factors for aortic aneurysms?
genetic defects such as marfan's, also smoking, hypertension, and hypercholesterolemia
48
What is an aortic dissection?
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
What are some symptoms that can present with an aortic aneurysm?
chest pain, upper back and left shoulder pain, hypotension; but most patients that have aneurysms are asymptomatic
50
What are the four P's in the clinical presentation of an aortic aneurysm or dissection?
Pallor, Pulselessness, Parasthesias, and Paralysis
51
How is familial thoracic aortic aneurysms inherited?
autosomal dominant inheritance
52
How many genes have been identified for involvement in FTAA?
4 genes on 4 different chromosomes
53
What is the difference between patients with FTAA and Marfan Syndrome?
in FTAA patients present at a much later age than patients with Marfan Syndrome
54
What is important to remember with genetic testing in FTAA?
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
What are the different types of cardiomyopathies?
dilated cardiomyopathy, hypertrophic cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic cardiomyopathy
56
What is hypertrophic cardiomyopathy?
the myocardium becomes thickened; especially in the left ventricle
57
What is restrictive cardiomyopathy?
walls become stiff and rigid but not thick; usually because of replacement of normal myocardium by scar tissue
58
What is arrhythmogenic cardiomyopathy?
right ventricular myocardium replaced with scar tissue
59
what are two of the most common hereditary cardiomyopathies?
``` hypertrophic cardiomyopathy (HCM)-disorder of the left ventricle arrhythmogenic cardiomyopathy (ARVD/C)- disorder of the right ventricle ```
60
How is hypertrophic cardiomyopathy most commonly inherited?
in an autosomal dominant pattern
61
What are the mutations involved in HCM? (hypertrophic cardiomyopathy)
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
What are some manifestations of HCM?
left ventricular hypertrophy, impaired left ventricular contractility, dyspnea on exertion, palpitation, chest pain, syncope
63
What is arrhythmogenic right ventricular dysplasia/ cardiomyopathy characterized by?
fibro fatty replacement of right ventricle myocardium and myocardial thinning
64
What are the clinical manifestations of ARVD/C?
arrhythmias, palpitations, chest pain, syncope
65
How many genes are known to be associated with ARVD/C?
8!

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