Pedigree - Dr. Taylor L1 Flashcards Preview

Ann's M2M - Weeks 3, 4 > Pedigree - Dr. Taylor L1 > Flashcards

Flashcards in Pedigree - Dr. Taylor L1 Deck (30):
0

Define locus

segment of DNA occupying a particular position or location on a chromosome

1

Define Allele

Alternative variant of a gene

2

Define wild-type

common or prevailing allele; present in the majority of individuals

3

Define variant or mutant allele

allele that differs from the wild-type

4

Define mutation

permanent change in the DNA sequence

5

Define Haplotype

a set of alleles at a locus or
a cluster of loci on a chromosome

6

Define polymorphism

When two or more alleles are relatively common

7

Define genotype

the set of alleles that make up a person's genetic constitution

8

Define phenotype

the observable expression of a genotype as a morphological, clinical, cellular or biochemical trait

9

Define pleiotropic

A single abnormal gene or gene pair that produces multiple diverse phenotypic effects

e.g. which organ systems are involved, signs / symptoms of a disease, when signs / symptoms occur

10

Define Single Gene Disorder

disorder determined primarily by the alleles at a single locus

11

Define
1. homozygous
2. heterozygous
3. compound heterozygote
4. hemizygous

1. pair of identical alleles at a locus
2. different alleles at a locus
3. two different _mutant_ alleles at a locus
4. only one copy of a gene (e.g. an abnormal gene on X in an XY male)

12

What's up with mitrochondrial DNA?

mitochondrial DNA (and the genes they encode for) are present in tens to thousands of copies per cell.

13

What is a proband?

individual of interest in a pedigree

also: propositus or index case

14

Define fitness in regards to a pedigree

measure of the impact of a condition on reproduction

the number of offspring an affected individual can have who survive to reproductive age

15

Hemophilia A and B are _______ disorders caused by mutations in which genes?

X-linked
F8 and F9 respectively

16

Racial predilection of hemophilia?

none. panethnic

17

Which is more rare, Hemophilia A or B?

B, 1 in 100,000
vs.
A, 1 in 10,000

18

What is the most common mutation in clotting factor VIII ?

intrachromosomal recombination between sequences in intron 22 of F8 and homologous sequences telomeric to F8

results in an inversion deleting the carboxyl terminus of VIII (the clotting protein)

19

Diagram how factors 8, 9 and 10 interact in the clotting cascade.

F8 & F9 complex
Activate F10
Active F10 activates more F8 & F9

---> amplification

20

Factor IX functions as a _________ and factor VIII functions as a _________.

protease
co-factor

21

What is the common mutation in Factor 9?

Many different mutations identified, but no _most common_ mutation has been identified.

22

Define hemathrosis

bleeding into joint spaces

23

Though rare, what is the genetic mechanism that could cause females to have hemophilia?

skewed X chromosome inactivation

24

What is the only current curative treatment for hemophilia A or B?

liver transplant

25

How are hemophilia A and B diagnosed and distinguished?

measurement of activity levels of factor VIII and IX

26

What is the (non-curative) standard of care for hemophilia and the current life expectancy?

Intravenous replacement of the deficient factor

65 years of age

27

When do most point mutations and the common F8 inversion mutation occur?

During male meiosis

28

When do deletion mutations for hemophilia usually occur?

During female meiosis

29

1. Mendel's Law of Segregation?
2. Mendel's Law of Independent Assortment?

1. Alleles segregate at meiosis into gametes.
2. The segregation of each pair of alleles is independent.