Demonstrate the methods for constructing a family history and for recognizing the inheritance patterns for the major modes of Mendelian inheritance

Question 1

Define consultand and proband:

Answer 1

• Consultand: seeking advice
• Proband: affected individual

Question 2

What is a family history?

Answer 2

• A record of health info about a person and their relatives

Question 3

Give 6 features of taking a family history

Answer 3

1. General Info
2. Family origin or racial/ethnic background
3. Health status, diagnosis, age of onset
4. Age/cause of death in deceased family members
5. Outcomes of pregnancies - patient/genetic relatives
6. 3 generations

Question 4

How would illutsrate you illustrate family history and why?

Answer 4

• Pedigree diagrams
• It shows genetic disorders which are inherited a family, hence used to workout the probability that someone in the family will inherit the condition = PEDIGREE ANLYSIS

Question 5

Give 2 ways each individual is indicated on a pedigree diagram?

Answer 5

• ROMAN NUMERAL:Which generation
• DIGIT: Individual within the generation - in age order (oldest on left)

Question 6

What does the horizontal line and vertical line indciate on a pedigree diagram?

Answer 6

• Horizontal: Mating
• Vertical: Offspring

Question 7

Draw the correct symbol (for males, females and unknown) for pediigree diagrams:

Answer 7

Question 8

What is Mandelian Inheritance and give 2 factors that it depends on?

Answer 8

• Genes/traits passed from parents to children

1. Autosomal/Sex = Location
2. Dominant/Recessive = Expression

Question 9

Give 5 modes of Mandelian Inheritance:

Answer 9

1. Autosomal Dominant
2. Autosomal Recessive
3. X linked Dominant
4. X linked Recessive
5. Mitochondrial

Question 10

Give 6 features of an autosomal dominant disease

Answer 10

1. 1 copy of disease allele = hetrozygote
2. 50% risk per pregnany
3. Affected parent
4. Pedigree = Vertical tranmsission
5. Every generation
6. MALES = FEMALES

Question 11

Huntington’s Disease is an example of….

Answer 11

• Autosomal dominant disease - high penetrance

Question 12

Huntington Disease: Define, give 3 symptoyms, 4 associated factors

Answer 12

• Progressive denegerative disorder of CNS
  
  • Dementia, movement disorder, personality changes
• Incurable, peak - 40 yrs, age of onset decreases, gain of function

Question 13

Give the mechanism of action for Huntingon Disease

Answer 13

1. Mutation on 4p16.3 - HUNTINGTON GENE
2. Trinucleotide expansion of CAG repeats (polyQ)
3. Accumulation of neuronal transport protein - HUNTINGTIN (mHTT)
4. This leads to neuronal (cell) death - Interference of synaptic transmission

Question 14

Give 6 features of autosomal recessive diseases

Answer 14

1. 2 copies of disease allele = Homozygote
2. Both parents are carriers
3. Pedigree = horizontal transmission ​
4. WITH EACH PREGNANCY = 25% disease 50% carrier 25% no disease
5. Not in every generation
6. MALES = FEMALES

Question 15

Give 2 features of hereditary hemochromatosis and it’s mechanism of action

Answer 15

1. Autosomal recessive disease charcatherised by iron overload
2. Loss of function

• Mutation on HFE gene (63 & 282 codon)

Question 16

Give 3 features of X-linked dominant inheritance

Answer 16

1. 1 copy of disease allele on X-chromosome
2. Males > females (symptoyms)
3. Females = 50% risk Males = All daughthers, no sons

Question 17

Give 2 features of X-linked recessive inheritance

Answer 17

1. Two copies of disease allele on X-chromosome
2. Males = hemizygous = 1 disease allele

Question 18

Give 3 features of mitochondrial inheritance

Answer 18

1. Affect males and females
2. Passed by females
3. Every generation

Question 19

Define dominant, recessive, homo recessive, homo dominant

Answer 19

• Dominant: 1 allele required
• Recessive: Both alleles required
  
  • Heterozygous- 2 different alleles
  • Homo recessive - 2 same alleles, recessive
  • Homo dominant - 2 same alleles, dominant

Question 20

Define the law of segregation:

Answer 20

• The alleles for each gene segreate so that each gamete carries one allele for each gene

Question 21

Define the Law of Independant Assortment and when might it not be true

Answer 21

• The genes of different traits segregate independently.
• If genes are close and cross over