Genetics

Question 1

The study of single or a few genes and their phenotypic effects

Answer 1

Genetics

Question 2

The study of all the genes in the genome and their interactions

Answer 2

Genomics

Question 3

How many % of the human genome encodes proteins?

Answer 3

<2%

Question 4

How many percent represents blocks of repetitive DNA sequences whose functions remain mysterious?

Answer 4

> 50%

Question 5

About 50% of spontaneous abortuses

Answer 5

Chromosomal abnormality

Question 6

1% of all newborn infants

Answer 6

Gross chromosomal abnormality

Question 7

Disorder related to mutations in single genes with large effects

Answer 7

Mendelian disorder

Question 8

Mutation in single genes with large effects

Answer 8

High penetrance

Question 9

• Structural or numerical alteration in the autosomes and sex chromosomes
• Uncommon but associated with high penetrance

Answer 9

Chromosomal disorders

Question 10

• More common
• Interactions between multiple genes and environment
• Small effect and is of low penetrance
• Multifactorial disorders

Answer 10

Complex multigenic disorders

Question 11

Variations in genes

Answer 11

Polymorphisms

Question 12

Examples of multifactorial disorders in complex multigenic disorders

Answer 12

• Atherosclerosis
• Diabetes Mellitus
• Hypertension
• Autoimmune diseases

Question 13

Permanent change in the DNA

Answer 13

Mutation

Question 14

Transmitted to progeny -> Inherited diseases

Answer 14

Germ Cell Mutations

Question 15

Not inherited

Answer 15

Somatic Cell Mutation

Question 16

Change in a single nucleotide base within a gene

Answer 16

Point mutations

Question 17

Subtype of Point Mutations:
Altered DNA, codes for the same amino acid

Answer 17

Silent Mutation

Question 18

Subtype of Point Mutations:
Altered DNA, codes for different amino acid

Answer 18

Missense Mutation

Question 19

Example of Missense Mutation

Answer 19

Sickle Cell Anemia
GAG (glu) -> GTG (val)

Question 20

Subtype of Point Mutations:
Altered DNA, codes for a stop codon

Answer 20

Nonsense Mutation

Question 21

Examples of Nonsense Mutation

Answer 21

• UAA
• UGA
• UAG

Question 22

Insertion or deletion of 1 or more nucleotides, shift the reading frame of the DNA strand

Answer 22

Frameshift Mutation

Question 23

If the number of base pairs involved is three or multiples of three, this type of mutation does not occur

Answer 23

Frameshift Mutation

Question 24

Amplification of a sequence of three nucleotides

Answer 24

Trinucleotide Repeat Mutation

Question 25

Increasing severity of clinical disease in each successive generation

Answer 25

Anticipation

Question 26

Having two different alleles for a single trait

Answer 26

Heterozygous

Question 27

Having identical alleles for a single trait

Answer 27

Homozygous

Question 28

- Manifested in the heterogenous state (Aa) - At least 1 parent of an index case is usually affected - Both males and females are affected and both can transmit the condition - When an affected person marries an unaffected one every child has 2/4 chances of having the disease - Age at onset is delayed

Answer 28

Autosomal Dominant Disorders

Question 29

In autosomal dominant disorders, when an affected person marries an unaffected one every child has ______ chances of having the disease

Answer 29

2/4

Question 30

In autosomal dominant disorders, age at onset is _____

Answer 30

Delayed

Question 31

- Largest category - Disease is expressed or as carriers - Trait does not usually affect the parents, but siblings may show the disease which have 1/4 chance of having the trait - Strong likelihood that affected individual (proband) is the product of consaguineous marriage - Onset is frequently early in life - Many mutated genes encode enzymes - Include almost all inborn errors of metabolism

Answer 31

Autosomal Recessive Disorders

Question 32

In autosomal recessive disorders, trait does not usually affect the parents, but siblings may show the disease which have _____ chance of having the trait

Answer 32

1/4

Question 33

In autosomal recessive disorders, strong likelihood that affected individual (proband) is the product of ______

Answer 33

Consaguineous marriage

Question 34

In autosomal recessive disorders, onset is frequently ____ in life

Answer 34

Early

Question 35

All sex-linked disorders are ______ and almost all are recessive

Answer 35

X-Linked

Question 36

- Affected males does not transmit the disorder to his sons, but all daughters are carriers - Heterozygous female does not express full phenotypic change because of paired normal allele - Sons of heterozygous women have 50% of receiving the mutant gene

Answer 36

X-Linked Recessive Disorders

Question 37

- Affected heterozygous female transmit to half her sons and half her daughters - Affected male parent transmit to all his daughters but none of his sons IF female parent is normal

Answer 37

X-Linked Dominant Disorders

Question 38

2 examples of x-linked dominant disorders

Answer 38

- Alports syndrome - Vitamin D resistant rickets

Question 39

Mnemonic for autosomal dominant disorders

Answer 39

Very Powerful DOMINANT Humans - Von willebrand disease/ Von hippel-lindau - Pseudo-hypoparathyroidism - Dystrophia myotonica - Osteogenesis imperfecta/ Osler-weber-rendu - Marfan syndrome - Intermittent porphyria - Neurofibromatosis - Achondroplasia/ Adult polycystic kidney disease - Noonan syndrome - Tuberous sclerosis - Hypercholesterolemia - Huntington's disease - Hypertrophic obstructive cardiomyopathy - Hereditary spherocytosis - Hereditary non polyposis coli - Hereditary hemorrhagic telangiectasia

Question 40

Examples of autosomal recessive conditions

Answer 40

- Sickle cell disease - Cystic fibrosis - Batten disease - Congenital deafness - Phenylketonuria (PKU) - Spinal muscular atrophy - Recessive blindness - Maple syrup urine disease

Question 41

Mnemonic for x-linked recessive disorders

Answer 41

"Oblivious Female Will Give Her Boys Her X-Linked Disorders" - OFWGHBHLD - Ocular albinism - Fabry disease - Wiskott-Aldrich syndrome - G6PD deficiency - Hunter syndrome - Bruton agammaglobulinemia - Hemophilia A/B - Lesch-Nyhan syndrome - Ducheene muscular dystrophy