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Flashcards in Exam 2 Deck (104)
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0
Q

Affected most persons with the disease or trait are notated as?

A

Aa

1
Q

Notation for Affected, rare and sometimes lethal?

A

AA

2
Q

Unaffected “normal” persons are notated as?

A

aa

3
Q

What is autosomal dominant inheritance?

A

When a disease or trait is caused by a dominant allele on an autosomal chromosome. Such mutations are expected to result in a phenotypic change

4
Q

With a mating of Aa x aa what is the ratio of affected to normals?

A

50:50 or 1:1

broken down as Aa, Aa, aa, aa

5
Q

With a mating of Aa x aa and the outcome being broken down as Aa, Aa, aa, aa. What are the odds of a 5th child being affected?

A

Each child is an independent event so the odds are 50:50

6
Q

What is the most common genetic notation for someone with an autosomal dominant condition?

A

Heterozygous Aa

7
Q

What are the 6 key features of someone with an autosomal dominance inheritance pattern?

A

1- an affected person has an infected parent
2- there is a ‘vertical’ look or pattern of affecteds seen in the pedigree
3-When and affected person mates with a normal, offspring are expected to be affected 50% of the time(and 50% are expected to be normal)
4- when the normal child of an affected person mates with a normal, normal offspring are expected
5- Sometimes an affected person does not have and affected parent, but there is a history of the condition in their family(this is a case of reduced penetrance)
6- Sometimes an affected person will appear in a pedigree with no prior history in that family( even though the condition is known to be dominant) this is a new mutation

8
Q

What type of genetic disorder is Huntington’s Disease?

A

Autosomal dominant

9
Q

Huntington’s disease:
Characterized by?
Mutation?
On set?

A
  • progressive involuntary twitching, personality change and dementia, and death
  • mutant gene has undergone a trinucleotide repeat or expansion mutation
  • this is a age onset disease that usually sets in at around 40 yrs of age
10
Q

What type of genetic disorder is Osteogenesis Imperfecta?

A

Autosomal dominant

11
Q

Osteogenesis Imperfecta is a disorder of what?

A

Connective tissue disorder of type 1 collagen

12
Q

OI is characterized by what?

A

brittle fragile bone disease and includes short stature, malformed bones, loose joints, blue sclera, opalescent teeth, and hearing deficit

13
Q

There are many types of OI which one is the most common?

A

Type 1

14
Q

Neurofibromatosis Type 1 is aka?

A

Von Recklinghausen Disease

15
Q

What genetic mode of inheritance is Neurofibromatosis Type 1?

A

Autosomal dominant

16
Q

What is Neurofibromatosis Type 1 characterized by?

A

Multiple neurofibromas

17
Q

What is Achondroplasia aka?

A

Achondroplastic dwarfism

18
Q

What mode of inheritance is Achondroplasia?

A

Autosomal dominant

19
Q

What is Achondroplasia characterized by and what is the rate of new mutations?

A

1 non-proportional dwarfism

2 new mutations account for roughly 75% of all cases, possibly as high as 90%

20
Q

What mode of inheritance is Marfan Syndrome?

A

Autosomal dominant

21
Q

What is Marfan syndrome characterized by?

A

Tall persons with dis-proportionally long limbs, arachnodactyly, subluxation of the eye lens, and cardio vascular defects

22
Q

Which mode of inheritance is Polycystic Kidney disease?

A

Autosomal dominant

23
Q

What is Polycystic Kidney disease characterized by and what is the time of onset?

A

Multiple kidney cysts and ADPKD is later onset(young adulthood)

24
Q

Define congenital

A

means present at birth and may be genetic

25
Q

Define hereditary

A

means “to be inherited” and is genetic

26
Q

Define Familial

A

means “runs in the families” and may or may not be genetic

27
Q

Define genetic

A

means “caused be a gene(s)” and is a rather broad term

28
Q

What is the most common blood coagulation disorder?

A

Von Willebrand’s disese

29
Q

What causes autosomal recessive inheritance?

A

A disease or trait is caused by a recessive allele on an autosomal chromosome

30
Q

When is a recessive allele not seen?

A

In the presence of a normal or dominant allele the mutation will not be seen in the phenotype

31
Q

What are the 3 possible genotypes and the outcomes for recessive alleles?

A

AA=unaffected (most of the population)
Aa=unaffected (normal, but termed a carrier)
aa=affected (persons with the disease)

32
Q

Looking at a recessive allele in the mating of Aa x Aa what would be the outcome ration of normal to affected?

A

3:1

33
Q

What would the outcomes be for a recessive mating of AA x Aa?

A

1:1 but all would be “normal”

34
Q

What are the 6 characteristics of autosomal recessive inheritance?

A

1 The vast majority of affected persons are the children of outwardly normal parents (and have no history in the families of the parents)
2 there is a “horizontal” look or patterns of affecteds in the pedigree
3 when the condition appears it has a recurrent risk of 25% in the sibship
4 When an affected mates with a normal, offspring are usually normal
5 When an affected mates with an affected, affected offspring are expected
6 if the abnormality is rare, one often finds consanguinity in the pedigree

35
Q

Does a normal person carry harmful recessive alleles?

A

Yes, harmful recessive alleles are relatively common in the human population and are usually referred to as part of the genetic load or burden

36
Q

With the mating of a Pp x Pp what is the chance of getting a carrier? This only applies to recessive alleles

A

PP, Pp, Pp, pp- (no pp because affected) so of PP, Pp, Pp only Pp will be a carrier leaving 2 out of 3 chance of being a carrier aka 2/3

37
Q

What mode of inheritance is PKU?

A

Autosomal recessive

38
Q

What is PKU a disorder of?

A

amino acid metabolism

39
Q

What does PKU result in and what are the clinical features of this?

A

Accumulation of phenylaline which leads to severe mental retardation, hypo-pigmentation, and an unusual odor

40
Q

How common is PKU?

A

uncommon(1 in 15,000)

41
Q

Albanism is aka?

A

hypomaelanism

42
Q

What is the mode of inheritance for Albanism?

A

autosomal recessive

43
Q

What is Albanism a disorder of?

A

amino acid metabolism

44
Q

What does Albinism result in and is it common?

A

results in a deficiency of melanin and is uncommon

45
Q

What is Tay-Sachs disease aka?

A

GM2 gangliosidosis

46
Q

What is the mode of inheritance for Tay-Sachs disease?

A

Autosomal recessive

47
Q

What is Tay-Sachs disease a disorder of?

A

Lipid metabolism

48
Q

Is Tay-Sachs disease common?

A

It is uncommon to rare, but variable depending on the population as in the case with the Ashkenazi Jews

49
Q

What is cystic fibrosis also known as?

A

CF or mucoviscidosis

50
Q

What is the mode of inheritance for cystic fibrosis?

A

Autosomal recessive

51
Q

What is cystic fibrosis a disorder of?

A

Chloride transport

52
Q

Cystic fibrosis results in exocrine gland secretion difficulties whcih lead to what?

A

very salty sweat, thick respiratory mucus secretions(leads to bacterial growth and respiratory infects), blockage of billiary tract(poor digestion), and pancreatic insufficiency

53
Q

What is the population prevalence of cystic fibrosis?

A

not common

54
Q

co-dominant or intermediate inheritance can be described as?

A

Heterozygotes have a different phenotype than either of the homozygous types(although often only a slight difference)

55
Q

What are the three possible genotype outcomes for co-dominance?

A
AA= unaffected 
Aa= semi-affected 
aa= affected
56
Q

What is familial hypercholesterolemia aka?

A

Hyperlipoproteiemia type IIa

57
Q

What mode of inheritance is familial hypercholesterolemia?

A

autosomal co-dominant

58
Q

What is familial hypercholesterolemia a disorder of?

A

High serum cholesterol specifically LDL’s due to an LDL receptor issue

59
Q

In familial hypercholesterolemia as a result of co-dominance there is a form of the disease for the heterozygous carrier and a very severe form of the disease when homozygous. What is the prevalence, cholesterol levels, and risk of MI for the mild form?

A

Mild form possibily as common as 1 in 500-the heterozygotes.
Total serum cholesterol in the 250-500mg/dl range
risk of MI is elevated: by age 60, seen in 85% of males and 50% of females

Severe form just know that is is very rare (serum cholesterol is 500-1000 and MI by age 20)

60
Q

What mode of inheritance is sickle cell anemia?

A

An autosomal co-dominant disorder

61
Q

What does sickle cell anemia cause?

A

vasculature gets occluded causing a vaso-occlusive crises and RBCs are rapidly destroyed causing anemia

62
Q

What are heterozygotes with sickle cell anemia like?

A

they are essentially normal, but RBCs will sickle in a low oxygen environment and they have what is called the sickle cell trait

63
Q

How predominant is sickle cell anemia?

A

African and/or mediterranean descent people

Also 1 in 12 african americans has the sickle cell trait

64
Q

What is the advantage to having the sickle cell trait?

A

Carriers of this mutation are somewhat resistant to the malaria infection

65
Q

What are 3 more examples of co-dominance?

A

beta-thalassemia, Factor V- Leiden Thrombolphilia, and ABO blood types

66
Q

What do Beta-Thalassemia heterozygotes and homozygotes have?

A

Heterozygotes have mild microcytic anemia (thalassemia minor)
Homozygous recessives have severe anemia (thalassemia major)

67
Q

What does Leiden Thrombophilia cause?

A

Common cause of venous embolism

one copy of the gene increases the chance of thromboembolism

68
Q

What is an example of perfect co-dominance?

A

ABO blood types

69
Q

What is SRY?

A

Sex determining Y region

70
Q

Where is the vast bulk of genes for determining sexual differences?

A

on the autosomes

71
Q

Heterogametic sex are male or females?

A

Males

72
Q

Homogametic sex are males or females?

A

Females

73
Q

What is a Barr body?

A

An X chromosome that is shut down

74
Q

What is klinefelter’s syndrome aka?

A

Testicular hyalinization

75
Q

What is the karyotype for klinefelters syndrome?

A

47, XXY

76
Q

Which gender is affected by klinefelters?

A

Males

77
Q

What are the characteristic features of klinefelters?

A

Sterility, tall/lanky, gynecomastia and the condition is uncommon

78
Q

What is turner’s syndrome also known as?

A

gonadal dysgenesis

79
Q

What is the karyotype for turners syndrome?

A

45, XO

80
Q

Which gender is affected by Turner’s syndrome?

A

females

81
Q

What are the clinical features of turners syndrome?

A

Sterility, broad”shield” chest, “webbed” neck,

82
Q

How common is Turner’s syndrome?

A

somewhat uncommon, also about 10% of all spontaneuos abortions

83
Q

Which people are more often described as “intersex”?

A

hermaphroditism

84
Q

Are sex chromosome abnormalities common?

A

yes

85
Q

What are genes on the Y chromosome known as? SRY for example?

A

holandric genes

86
Q

What is the only type of x linked inheritance that we are learning about?

A

X-linked recessive

87
Q

Since males only have 1 x linked chromosome what would that be called?

A

Hemizygous

88
Q

With the mating of a male and a female carrier what would be the outcome? Aa, AY

A

AA, Aa, AY, aY This would give a ration of 3:1 affected. Only a male would be affected

89
Q

What are the 2 characteristics of X-linked recessive inheritance?

A

1 The vast majority of affected persons are males

2 An affected male cannot pass the trait on to his son or to further generations though his son

90
Q

What genetic mode of inheritance is Hemophilia A?

A

X-linked recessive

91
Q

What is Hemophilia A due to?

A

Missing the blood clotting factor VII

92
Q

How common is Hemophila A and what does it result in?

A

It is very uncommon and results in bleeding

93
Q

Which gender is affected by Hemophilia A?

A

Only males

94
Q

What is the genetic mode of inheritance for common color blindness?

A

X-linked recessive

95
Q

How common is common color blindness and what does it cause?

A

It is very common(1 in 12 males) and results in red-green confusion

96
Q

WWhat mode of inheritance is Duchenne-Type Muscular Dystrophy?

A

X-linked recessive

97
Q

What mode of inheritance is fragile-X syndrome?

A

X-linked recessive

98
Q

What does fragile x cause in a person?

A

mental retardation

99
Q

What is the most common cause of mental impairment?

A

fragile x syndrome

100
Q

What mode of inheritance is male pattern baldness?

A

x-linked recessive

101
Q

male pattern baldness is aka?

A

androgenic alopecia

102
Q

What is up with male pattern baldness?

A

It is a pattern of hair loss in males due to the presence of androgen hormones

103
Q

Is male pattern baldness common?

A

Yes very common