Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

KCSU17 Genetics > Sex linked disorders > Flashcards

Sex linked disorders Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

inheritance of genes located on sex chromosomes

A

sex linked inheritance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

males and sex chromosomes

A

receive their only X from mom

x-linked mutation will be present in any male with disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

females and sex chromosomes

A

X chromosomes from both parents

may not express the disease if mutation exists (x inactivation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

x linked recessive

A

phenotype is not expressed in females, exclusively men

all daughters of affected males are carriers

no male to male transmission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

x linked dominant

A

phenotype is consistently expressed in female

females > males

all daughters of affected males are affected but not sons

Men usually die in uterine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

y linked

A

affects only males

affected males always have affected fathers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

x linked recessive probability

A

affected men born from carrier mothers have 50% risk of disease

no male to male transmission

affected male can only pass disease onto daughter (she will be a carrier)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

x linked dominant probability

A

child of an affected female has 50% risk of disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

y linked transmission

A

affected dad CANNOT give to his daughter

affected dad CAN give to his son

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

mitochondrial traits transmission

A

appear in every generation

can affect males and females

fathers do not pass mitochondrial traits, only ovum contributes mitochondria to offspring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

x inactivation

A

ability of second X chromosome to compensate for a mutant or defective gene on other X chromosome

occurs in every female, during development. Randomly, so that females are essentially mosaics

incomplete, so some regions remain active in all copies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

x chromosome

A

X is much larger than Y so it codes for many proteins

females have twice the dosage of X than males

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

calico cats

A

example of X inactivation
alternating black and orange spots show the mosaicism in female cats

one contains X with active orange allele and one with black allele

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

X linked recessive disorders discussed in this class

A

hemophilia
Duchenne muscular dystrophy
Becker muscular dystrophy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

hemophilia A and B are distinguished by

A

aPTT test

tests intrinsic pathway, both will have elevated aPTT

factor 8 and 9, involved in intrinsic pathway, are elevated

other than this test, hemophilia A and B are indistinguishable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

hemophilia

A

sex linked recessive

severe bleeding disorder

85% are A and 15% are B

aPTT test distinguishes

prolonged or severe bleeding from wounds and hemorrhage in joints and muscles causes hemearthroses and intracranial disorder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

genetic abnormality:

hemophilia A

A

long arm q of X chromosome (F8C gene)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

protein affected:

hemophilia A

A

deficiency or defect in factor 8

clotting factor, therefore causes excessive bleeding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

treatment for hemophilia A and B

A
  1. monoclonal purified, plasma derived factor VIII (can cause infection)
  2. recombinant Factor VIII (non human, made in lab so safer)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

hemophilia B

A

aka christmas disease

caused by mutation on F9 of X, coding for Factor 9 Leyden

severe hemophilia during childhood, spontaneous resolution during puberty

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

most common and most severe form of muscular dystrophy

A

Duchenne muscular dystrophy

characterized by progressive weakness and loss of muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

genetic abnormality

Duchenne muscular dystrophy

A

Xp21

deletion or duplication producing FRAMESHIFT mutation

more common in males

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Duchenne muscular dystrophy

protein affected

A

dystrophin

results in ABSENCE of protein, most likely responsible for maintaining structural integrity of cytoskeleton

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Duchenne muscular dystrophy

pathophysiology

A

lack of dystrophin causes muscle cells to die as they are stressed by muscular contractions

muscle death causes release of creation kinase, CK, into the blood stream

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Duchenne muscular dystrophy

clinical manifestations

A

progressive weakness and loss of muscle

cardiomyopathy in all affected after 18, few live beyond 30

respiratory problems and DMC as MC cause of death

proximal weakness, waddling gait, difficulty climbing

pseudo hypertrophy of calves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Duchenne muscular dystrophy

expression pattern

A

symptoms seen before age 5

female heterozygote carriers often show some symptoms

DMD is rapidly progressive, children in wheel chair by age 12

Gowers maneuver to ID

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Duchenne muscular dystrophy

treatment

A

mandage cardiomyopathy

prednisone to improve strength, function

28
Q

Becker muscular dystrophy

genetic abnormality

A

Xp21, dystrophin gene

IN-FRAME mutation

29
Q

Becker muscular dystrophy

protein affected

A

dystrophin

DECREASED LEVELS

10% from spontaneous mutation

30
Q

Becker muscular dystrophy

clinical manifestations

A

slower progression, less severe than DMD

never lose ability to walk

later onset skeletal muscle weakness

DMC is MC cause of mortality

31
Q

Becker muscular dystrophy

expression pattern

A

11 years of age

32
Q

most common inherited cause od mental retardation

A

Fragile X syndrome

only need one mutation to cause disease (both males and females) MORE MEN

33
Q

Fragile X syndrome

genetic abnormality

A

FMR1 gene, Xq28

expansion of CGG repeat

34
Q

Fragile X syndrome

penetrance levels

A

normal CGG length is 6-54
normal, transmitting males = 60-200
affected individuals = 200-thousands of CGGs

anticipation is seen with Fragile X (# increases w/generation and severity)

35
Q

anticipation Fragile X syndrome in men

A

permutation is passed thru men then it doesn’t significantly increase in size

dad can give to daughter, not son

36
Q

anticipation Fragile X syndrome in women

A

CGG expansion is unstable, high risk of it expanding to full mutation in children

mom can give to daughter (50%) and son as well

37
Q

Fragile X syndrome

protein affected

A

FMRP or FMR-1

protein is necessary for normal brain development and function

38
Q

Fragile X syndrome

pathophys

A

when repeats expand over 200, the gene is turned off = full mutation

this causes decrease in protein product which causes manifestations

39
Q

Fragile X syndrome

clinical manifestations

A

distance facial appearance (lg. head, long face, lg. ears, macroorchidism)

moderate to severe mental retardation

physical features distinct after puberty
normal life expectancy

40
Q

Fragile X syndrome

expression pattern

A

depends on number of repeats

females there is variability in phenotype expression due to effect of x-inactivation

41
Q

Fragile X syndrome

penetrance

A

reduced pentrance

42
Q

Rhett syndrome

A

x-linked dominant

disorder of brain development

occurs exclusively in females

43
Q

rhett syndrome

genetic abnormality

A

MECP2 gene on X chromosome (Xq28)

44
Q

Rhett syndrome

protein affected

A

MECP2
regulates other genes in brain by switching them off

binds a MeCP2 protein to methylated cells to prevent access to DNA transcriptions

45
Q

Rhett syndrome

pathophys

A

MECP2 mutations disrupt normal functioning of nerve cells

normal brain development until 6-18 months

46
Q

why do symptoms of Rhett syndrome not appear until 6-18 months?

A

by 6 months new neuronal cells are maturing and certain proteins become active and MeCP2 must interact with them to promote new and existing brain cell development

47
Q

Rhett syndrome

clinical manifestations

A

disruption of neurotransmitters causes excessive anxiety (withdrawn and anxious)

autistic like behaviors, acquire specific symptoms like teeth grinding and hand wringing

48
Q

MECP2 and anxiety

A

normally controls activity of CRH
this mutations results in overabundance of CRH in brain

therefore Rhett syndrome results in excessive anxiety and stress

49
Q

Rhett syndrome

expression pattern

A

x-inactivation

50% of mutant gene and 50% of normal gene causes Rhett to develop (50:50)

if majority of x cells turn off chromosome that includes mutant MECP2 gene then mild disorders develop and patients don’t show the pattern

50
Q

Rhett syndrome

penetrance pattern

A

not all children with MECP2 mutations will develop classic Rhett syndrome

51
Q

Rhett syndrome treatment

A

gene therapy is being developed

52
Q

x-linked dominant disorders discussed in this class

A

Rhett syndrome

Fragile X syndrome

53
Q

Y-linked disorders genetic transmission

A

dad cannot give it to his daughter but CAN give to his son

54
Q

y chromosome

A

plays a crucial house keeping role into cell

referred to as pseudoautosomal

55
Q

Y-linked genes

A

SRY gene - specifies male fathers and maleness

hypertrichosis pinnae auris – hairy ears, gene found on Y chromosome

56
Q

Mitochondrial disorders

A

appear in every generation of a family

affect both males and females

fathers DO NOT pass mitochondrial traits to children, only mothers

57
Q

mitochondria

A

have their own DNA

found in tale of sperm, falls off when fertilization occurs

therefore only ovum contributes to mitochondria in offspring

58
Q

heteroplasmy

A

fraction of molecule in mtDNA that carry a mutation

phenotype of a cell depends on percentage of mutated DNA it contains

severity of condition correlates with extent of heteroplasmy

59
Q

mitochondrial disorders in this class

A

Leber Hereditary Optic Neuropathy (LHON)

Myoclonic Epilepsy with Ragged Red Fiber Syndrome (MERRF)

Pearson Syndrome

60
Q

LHON

A

bilateral loss of central vision caused by atrophy of optic never

vision disappears within a few weeks

appears in second or third decade of life and affects more men than women (classic)`

61
Q

Myoclonic Epilepsy with Ragged Red Fiber Syndrome

A

MERRF

characterized by myoclonic epilepsy

generalized convulsions of myopathy with presence of ragged red fibers

clumps of diseased mitochondria that accumulate and aggregate in individual muscle fivers

62
Q

LHON is caused by mutations

A

mtDNA
component of the elevon transport chain
specific inability to generate ATP

63
Q

MERRF is caused by mutations

A

mtDNA
caused by mutations of mitochondrial tRNA (tRNALys)

caused by a general defect in mitochondrial protein synthesis

64
Q

Pearson Syndrome

A

first year of life

children usually die before three years of life

affects hematopoiesis and endocrine pancreatic function

anemia with vacuolization of bone marrow precursors, manifested with microcytic anemia, thrombocytopenia, neutropenia

65
Q

mitochondrial genomes reading assignment

A

mitochondria contain multiple genomes, every cell contains multiple mitochondria

req. for energy production vary from one tissue to another

mutations in mitochondrial DNA affect only a fraction of mitochondrial genomes within a given individual

KCSU17 Genetics (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions