L3: Modes of Inheritance Flashcards
(60 cards)
1
Q
Modes of Inheritance
A
- Mendelian inheritance (single gene traits)
- Multi-factorial inheritance
- Non-traditional inheritance
2
Q
Def of Mendelian Inheritance (Single Gene Traits)
A
- The inheritance of single-gene disorders
3
Q
Def of Locus
A
Specific position of gene on the chromosome
4
Q
Def of Alleles
A
5
Q
Introduction to Genetic Pedigree
A
6
Q
Types of Mendelian Inheritance
A
7
Q
Def of AD Inheritance
A
8
Q
Risk of Transmission in AD Inheritance
A
9
Q
Rules of AD Inheritance
A
…
10
Q
Sex affected in AD Inheritance
A
Male & Female are affected in equal proportion
11
Q
Generations affected in AD Inheritance
A
- Transmitted from one generation to the next
- Sporadic cases with high paternal age suggest new mutation
12
Q
Transmission between sexes in AD Inheritance
A
- All forms of transmission between sexes are observed (male to male - male to female // female to female - female to male)
- Male to male transmission exclude the gene on X chrom
13
Q
Examples of AD Inheritance
A
14
Q
Sporadic cases with AD disorders suggest ……..
A
New Mutation
15
Q
Male to Male transmission exclude ……..
A
X-Linked Inheritance
16
Q
Def of AR Inheritance
A
17
Q
Risk of Transmission in AR Inheritance
A
18
Q
Sex affected in AR Inheritance
A
Male & Female are affected in equal proportion
19
Q
Generations affected in AR Inheritance
A
Affected individual usually only in a single generation
20
Q
Consanguinity supports …….
A
AR Inheritance
21
Q
Examples of AR Inheritance
A
22
Q
Factors affecting AD Gene Expression
A
- Pleiotropy
- variable Expressivity
- Reduced penetrance
- New Mutations
23
Q
Def of Pleiotropy
A
A single gene (AD) that may give rise to two or more apparently unrelated effects.
24
Q
Etiology of Pleiotropy
A
- Different mutations in the same gene
25
Examples of **Pleiotropy**
In tuberous sclerosis, some affected individuals may have all features (learning difficulties, epilepsy, facial rashes,...)
26
Def of **Variable Expressivity**
- Striking variation in the clinical features of AD disorders from person to person, even in the same family.
27
Examples of **Variable Expressivity**
PCKD
28
Def of **Reduced penetrance**
Penetrance describes the frequency with which phenotypic manifestation of a gene are expressed.
29
Examples of **Reduced penetrance**
30
Def of **New Mutations**
- AD disorders sometimes appear in a child of unaffected parents because of a spontaneous mutation
31
Etiology of **New Mutations**
- May be associated with advanced paternal age
32
Examples of **New Mutations**
- About 80% of patients with achondroplasia have experienced a mutation in (FGFR3) gene.
33
Difference between penetrance & Expressivity
34
Pseudodominance Inheritance
35
Co-dominance Inheritance
36
Incomplete Dominance
37
Types of **Sex Chromosome Inheritance**
- X Linked Inheritance
- Y Linked Inheritance
38
Types of **X-Linked inheritance**
- XL Dominant
- XL Recesive
- Sex Controlled
- Sex Limited
39
**X-Linked Dominant Inheritance**
- Whci sex is more affected?
- Females are affected more frequently than males
- Females are affected less severely than males
40
**X-Linked Dominant Inheritance**
- Transmission between sexes
- Affected female can transmit the disorder to both male and female offspring
- Affected males can only transmit the disorder to their daughters but not sons.
41
In X-Linked Dominant Inheritance
- Affected males can only transmit the disorder to .....
their daughters but not sons.
42
Examples of X-Linked Dominant Inheritance
- Hypophosphatemic rickets
- Incontinentia pigmenti
43
Def of **X-Linked Recessive Inheritance**
- An x-linked recessive trait is one determined by a gene carried on the X chromosome and usually only manifest in males
44
Risk of Transmission in **X-Linked Recessive Inheritance**
45
Risk of Transmission in **X-Linked Recessive Inheritance**
- Male affected married normal female (Hemophilia)
- All daughters obligate carriers
- All sons normal
46
Risk of Transmission in **X-Linked Recessive Inheritance**
- Carrier female (X-LR married normal male
- Sons: 50% chance affected
- Daughters: 50% chance carrier
47
**X-Linked Recessive Inheritance**
- Which sex is more affected?
- Males usually only affected.
48
A male with mutant allele on his single x chromosome is said to be .... for that allele.
hemizygous
49
**X-Linked Recessive Inheritance**
- Transmission Between Sexes
- Transmitted through unaffected carrier females to their sons
- Males cannot transmit the disorder to their sons i.e. no male to male transmission.
- A male transmits his x chromosome to each of his daughters and his Y chromosome to each of his sons.
50
**X-Linked Recessive Inheritance**
- Examples
- Hemophilia A
- G6PD deficiency
- Muscular dystrophy
- Color blindness
51
Explain Sex controlled inheritance
- Some genes gives an effect in male different from that in female
52
Examples of **Sex controlled inheritance**
Tone of voice (High pitch in male and vice versa)
53
Explain Sex limited inheritance
Gene expresses itself in only one sex and not the other
54
Example of **Sex limited inheritance**
PLUS Y-Linked Inheritance
Gene determining a heavy beard in male
55
Def of **Multi-Factorial Inheritance**
56
In **Multi-Factorial Inheritance**
- The magnitude of the trait is determined by:
57
Normal traits inherited by Multifactorial Inheritance
58
Abnormal traits inherited by Multifactorial Inheritance
59
Def of **Non-Traditional Inheritance**
- Inheritance patterns which do not fall into the chromosomal, single gene, or multifactorial categories
60
Examples of **Non-Traditional Inheritance**
* Cytoplasmic inheritance
* Mosaicism
* Uniparental disomy
