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Flashcards in Genetics Deck (16):
1

Incomplete penetrance example

BRCA gene mutations do not always result in breast or ovarian cancer

2

Loss of heterozygosity

Tumor suppressor genes require one mutation and deletion/mutation of second gene before cancer develops
NOT TRUE OF ONCOGENES
Rb and two hit hypothesis
Lynch syndrome
Li-Fraumeni syndrome

3

Linkage disequilibrium

Tendency for alleles at 2 linked loci to occur together more or less often than expected by chance. Measured in a population and varies with different populations.

4

Mosaicism

Genetically distinct cell lines in the same individual
McCune-Albright syndrome: mutation in G protein signaling
--unilateral cafe-au-lair spots, precocious puberty, multiple endocrine abnormalities,

5

McCune-Albright Syndrome

Mosaicism -only survivable in patients with Mosaicism
Mutation affecting G protein signaling
Unilateral cafe au lait spots
Polyostotic fibrous dysplasia, precocious puberty, multiple endocrine abnormalities
LETHAL if mutation is prior to fertilization

6

Locus heterogeneity

Mutations at different loci can produce a similar phenotype
Ex: albinism

7

Allelic heterogeneity

Different mutations in the same locus produce the same phenotype
Ex: beta thalassemia

8

Heteroplasmy

Presence of both normal and mutated mtDNA
Variable expression in mitochondrially inherited disease

9

Uniparental disomy

Consider in an individual manifesting with a recessive disorder when only one parent is a carrier

10

Hardy Weinberg population

1. No mutation occurring at the locus
2. Natural selection not occurring
3. Completely random mating
4. No net migration

11

Imprinting

Only one allele is active and the other one is inactive
Ex: angelman and prader-willi

12

Prader-Willi syndrome

Paternal is mutated
Maternal imprinting--mother's gene is usually silent (child may also receive two "silent" genes from the mother)
Child has hyperphagia, obesity, intellectual disability, hypogonadism and hypotonia
Will used to eat his feelings and was not aroused.

13

Angelman syndrome

Maternal deleted/mutated
Paternal imprinting
"Happy puppet" -- It's all in their head (seeing Angels)
Seizures, ataxia, severe MR

14

Pleiotropy

One gene contributes to multiple phenotypic effects
PKU-musty odor, light skin and intellectual disability

15

Hypophosphatemic Rickets

X linked dominant
Vit D resistant Rickets
Increased phosphate wasting at proximal tubule

16

Mitochondrial Inheritance

Mitochondrial myopathies
Lactic acidosis, CNS disease, myopathy
Ex: MELAS--failure in oxidative phosphorylation
"ragged red fibers" on muscle biopsy