AUTOSOMAL DOMINANCE

Question 1

what is the Mendelian inheritance

Answer 1

Mendelian inheritance is a type of biological
an inheritance that follows the principles originally
proposed by Gregor Mendel
§ Mendel’s Principles of Heredity

Question 2

the mendelian inheritance is a pattern for

Answer 2

single-gene disorders

Question 3

These rules for inheritance patterns are used

Answer 3

continuously in genetics practice

Question 4

which chromosomes do we look at

Answer 4

Autosomes (22 pairs):
two of every autosome
therefore two copies of
each autosomal gene
HOMOLOGOUS

Question 5

autosomal dominant

Answer 5

An autosomal dominant trait is that which manifests
in the heterozygous state, that is, in a person
possessing one abnormal/ mutant allele and the
another one a normal allele

Question 6

autosomal

Answer 6

Chromosome 1-22
(not sex
chromosomes)

Question 7

heterozygous state

Answer 7

When two alleles differ
from one another at a part
locus of a diploid
organism

Question 8

mutant allele

Answer 8

Arising from an alteration in
the DNA sequence of the gene
which brings about a change
in the resultant protein

Question 9

how is autosomal dominant mutant passed on

Answer 9

There are two copies of every autosomal gene
§ Both copies of the gene function to produce a product
(i.e.protein)

§ One copy of each gene is passed to a child from their
mother and the other from the father

§ Dominant mutation on one gene will produce the
condition despite the working copy

§ (Only 1 copy needed to express the condition)

Question 10

example

Answer 10

§ There are 2 copies of each
gene

§ If only one allele mutated § i.e. Paternal § Phenotype to manifest § Allele 1 (Paternal) is
dominant to allele 2
(maternal)

Question 11

probability of inheritance

Answer 11

§ Punnet square

§ Calculate the mathematical probability of inheriting a specific trait /
mutation

§ Predict the genotypes of an offspring based on parental genotype

Question 12

Aa

Answer 12

affected

Question 13

aa

Answer 13

unaffected

Question 14

both parents affected, Aa and Aa

Answer 14

1/ 4 or 25% chance = unaffected
2/ 4 or 50% chance = affected (heterozygous)
1/ 4 or 25% chance = affected (homozygous)

Question 15

achondroplasia

Answer 15

• Form of short-limbed dwarfism
• Mutation in the FGFR3 gene
• Cartilage not converted to bone
• Breathing problems, recurrent ear
infections etc.
• Double are lethal

Question 16

other examples

Answer 16

Neurofibromatosis type 1
Huntington disease
Familial hypercholesterolemia
Inherited predisposition to some cancers

Question 17

Occurs in every generation § The number of affected males =

affected females

Answer 17

true

Question 18

Only 1 copy needed to express the condition

Answer 18

true

Question 19

Male to female and female to male transmission (autosomal)

Answer 19

true

Question 20

At least one parent of an affected individual is (usually) affected

Answer 20

true

Question 21

With each pregnancy, an affected individual has a 50% (1 in 2) chance of
passing on the mutant and therefore having an affected child

Answer 21

true