Brainscape's Knowledge GenomeTM

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


See full index

Genetics > Patterns of Inheritance: Lect 3-6 > Flashcards

Patterns of Inheritance: Lect 3-6 Flashcards

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

Recurrence risk

A

probability that the offspring of a couple will express the genetic disease.
-depends on mode of inheritance.

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

Autosomal Dominant:

define and name disorders.

A

-manifest in heterozygote state
-male-male transmission.
-50% recurrence risk to offspring regardless of child’s sex.
DISORDERS: NO HA2M2
-Familial hypercholesterolemia
-Huntington disease
-Myotonic dystrophy
-Marfan syndrome
-Osteogenesis imperfecta
-Achondroplasia
-Neurofibromatosis type I
-Acute intermittent porphyria

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

Mytonic dystrophy

A
  • mutation in DMPK gene
  • most pleitropic of all 3x repeat disorders.
  • wasting of muscles, cataracts, heart conduction defects, endocrine changes and myotonia.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Achondroplasia

A

-FGFR3 mutations (differentiation of cartilage to bone)

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

Neurofibromatosis

A
  • NF1 mutation; codes for a tumor suppressor protein.
  • allelic hetrogeneity
  • variable expressivity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Haplo-insufficiency:

A
  • loss of function mutation; half nl levels of the gene product result in phenotypic effects
  • FH, AIP, OI type I.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Dominant negative:

A
  • mutant gene product interferes w/ the function of the nl gene product.
  • OI type II, III, IV and Marfans.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Gain of function:

A
  • increased levels of gene expression or development of new function.
  • Huntington and Achondroplasia.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Autosomal recessive:

define and list disorders

A
  • both parents are carriers; phenotypically nl.
  • siblings commonly affected, horizontal inheritance, male:female equal.
  • increased by consanguinity.
  • recurrence risk = 25%; 2/3rd carrier risk among sibs.

DISORDERS: no 2/3rds to delayed onset

  • Cystic fibrosis
  • Sickle cell anemia
  • Phenylketonuria
  • Tay-Sachs disease
  • Congenital deafness
  • Hemochromatosis *delayed onset
  • Alkaptonuria *delayed onset
  • Homocytinuria
  • Galactosemia
  • SCID
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Loss of function:

A

reduced activity (hypomorph) or complete loss of gene product (amorph). ex: enzyme deficiencies

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

Hemochromatosis:

A
  • iron overload disorder
  • C282Y mutation on HFE gene
  • delayed age of onset
  • allelic hetrogeneity
  • variable expressivity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

SCIDS:

A

-due to ADA deficiency = build up of dATP which is toxic to B and T cell development.

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

Psuedo-autosomal dominant

A

an AR condition in two or more generation, thereby appearing to follow a dominant inheritance pattern.

  • vertical transmission
  • due to Heterozygote adv: high carrier freq. (sickle cell in Africa)
  • higher incidence of consanguinity (geographical, social/religious isolation)
  • assortative mating
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

X-linked recessive disorders:

A
  • more common in males *hemizygous.
  • affected father = all daughters are carriers. w/ no male to male

DISORDERS:

  • Dystrophin assoc. muscular dystrophy (Duchenne and Becker)
  • G6PD
  • Hemophilia A and B
  • Lesch-Nyhan syndrome: HGPRT deficiency
  • Red-green color blindness
  • X-linked SCID (SCIDX1 gene)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Hemophilia A

A

deficiency of clotting factor VIII and involves inversions of an intron sequence.
-allelic heterogeneity

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

X-linked SCID

A

-defect in the gamma rcp for several different interleukins (IL2RG)

17
Q

Manifesting heterozygote

A

due to assymeteric/skewed X-inactivation.

-mutant X is active in most of her cells.

18
Q

X-linked dominant disorders

A
  • male:female equal
  • affected male transmits to all his daughters but none of sons.

DISORDERS:

  • Rett syndrome
  • Incontinentia pigmenti
  • Vitamin D resistant Rickets
19
Q

Rett syndrome

A
  • affects females more

- males die in utero or after birth.

20
Q

Incontinentia pigmenti

A
  • males die in utero
  • females less severely affected
  • Marble cake appearance; hyperpigmentation, mental retardation and retinal detachment in some pts.
  • variable expressivity.
21
Q

Y-linked inheritance

A
  • only males affected; usually causes sterility and aren’t passed on.
  • mutations in the SRY gene
  • H-Y histocompatibility antigen
  • Hairy ears
22
Q

Non-penetrance:

Fully penetrant:

A
  • indiv has the disease genotype but doesn’t display the disease phenotype.
  • if all carrying the mutation, express the manifestations of the disease
23
Q

Incomplete penetrance

A

may be dependent of on age,

24
Q

Waardenburg syndrome

A
  • pleiotropic and variable expression

- white forelock, sensorineural hearing loss, heterochromia

25
Q

Locus heterogeneity

A

mutations at diff loci that cause the same disease phenotype.

  • OI
  • Sensorineural hearing impairment
  • Charcot Marie Tooth (AD, AR, XL)
  • SCID (AR, XL)
  • Breast cancer BRCA1/2
26
Q

Allelic heterogeneity/Compound heterozygotes

A

diff mutations at the same locus cause the disease

  • NF1
  • Hemochromatosis
  • Cystic fibrosis
  • Hemophilia A
27
Q

New Mutation

A
  • transmitted from an unaffected parent to an affected offspring.
  • no family hx of the disease
  • increased age of father observed
  • NF1, FGFR3, Duchenne, OI, Marfan
28
Q

Germline mosaicism

A

-mutation present in a proportion of the germline cells; somatic cells will show no mutation.

29
Q

Mitochondrial inheritance

A
  • from mother
  • all offspring of affected female are affected.
  • heteroplasmy: variable expression in mitochondrial disorder.

DISORDERS:

  • MELAS: Mitochondrial encephalomyopathy lactic acidosis and stroke-like episdoes
  • Leber hereditary optic neuropathy: progressive blindness around 20-30yrs
  • MERRF: Myoclonic epilepsy w/ ragged red muscle fibers.
30
Q

Digenic disorder

A
  • mutations in two genes

- Retinitis pigmentosa: mutation in two indep genetic loci ROM1 and peripherin.

31
Q

Imprinting:

A

methylation of specific loci and silencing of the gene.

32
Q

Prader Willi:

A
  • microdeletion of paternal chrom 15 SNRPN 70%
    • detected by FISH
  • maternal uniparental disomy of chrom 15; w/ two active copies of UBE3A via trisomy rescue and no SNRPN 30%
    • detected by methylation analysis; restriction enzyme does not cleave methylated DNA
  • children are obese, w/ mental and development delay and underdeveloped genitalia, hypotonia and failure to thrive.
  • Polymorphic marker analysis can be used to differentiate the cause of PW syndrome.
33
Q

Angelman syndrome

A
  • deletion of maternal UBE3A gene
  • uniparental disomy of paternal chrom 15 (2 copies of active SNRPN)
  • severe mental retardation, seizures, puppet like posture
34
Q

Triple repeat disorders

A
  • Fragile X: at the promoter/5’ region of the FMR1 gene; CGG. Anticipation observed in mother.
  • Friedrich ataxia: in an intron, resulting in formation of heterochromatin GAA
  • Huntington: in the coding region; polyglutamine expansion CAG. Anticipation observed in father w/ >40 repeats.
  • Myotonic dystrophy: at the 3’ end CTG. Anticipation observed in mother.
35
Q

Anticipation

A

-indiv in recent generation develops disease at an earlier age w/ greater severity.

36
Q

Fragile X syndrome

A

-Increased methylation and silencing of the FMR1 gene.

  • poor muscle tone, macro-orchidism, sunken in chest, elongated head, prominent ears, develop language skills at 4 or 5 yrs. Difficulty w/ eye contact, freq. hand slapping when excited.
  • less severe in females
  • diagnostic test: Southern blot analysis
  • X chrom shows breakage in a folate deficient medium

Genetics (19 decks)

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