Pedigree - Dr. Taylor L1

Question 0

Define Allele

Answer 0

Alternative variant of a gene

Question 1

Define locus

Answer 1

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

Question 2

Define wild-type

Answer 2

common or prevailing allele; present in the majority of individuals

Question 3

Define variant or mutant allele

Answer 3

allele that differs from the wild-type

Question 4

Define mutation

Answer 4

permanent change in the DNA sequence

Question 5

Define Haplotype

Answer 5

a set of alleles at a locus or

a cluster of loci on a chromosome

Question 6

Define polymorphism

Answer 6

When two or more alleles are relatively common

Question 7

Define genotype

Answer 7

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

Question 8

Define phenotype

Answer 8

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

Question 9

Define pleiotropic

Answer 9

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

Question 10

Define Single Gene Disorder

Answer 10

disorder determined primarily by the alleles at a single locus

Question 11

Define

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

Answer 11

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)

Question 12

What’s up with mitrochondrial DNA?

Answer 12

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

Question 13

What is a proband?

Answer 13

individual of interest in a pedigree

also: propositus or index case

Question 14

Define fitness in regards to a pedigree

Answer 14

measure of the impact of a condition on reproduction

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

Question 15

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

Answer 15

X-linked

F8 and F9 respectively

Question 16

Racial predilection of hemophilia?

Answer 16

none. panethnic

Question 17

Which is more rare, Hemophilia A or B?

Answer 17

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

Question 18

What is the most common mutation in clotting factor VIII ?

Answer 18

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)

Question 19

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

Answer 19

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

—> amplification

Question 20

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

Answer 20

protease

co-factor

Question 21

What is the common mutation in Factor 9?

Answer 21

Many different mutations identified, but no most common mutation has been identified.

Question 22

Define hemathrosis

Answer 22

bleeding into joint spaces

Question 23

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

Answer 23

skewed X chromosome inactivation

Question 24

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

Answer 24

liver transplant

Question 25

How are hemophilia A and B diagnosed and distinguished?

Answer 25

measurement of activity levels of factor VIII and IX

Question 26

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

Answer 26

Intravenous replacement of the deficient factor

65 years of age

Question 27

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

Answer 27

During male meiosis

Question 28

When do deletion mutations for hemophilia usually occur?

Answer 28

During female meiosis

Question 29

1. Mendel’s Law of Segregation?

2. Mendel’s Law of Independent Assortment?

Answer 29

1. Alleles segregate at meiosis into gametes.

2. The segregation of each pair of alleles is independent.