Pattern of Genetic Inheritance Flashcards

1
Q

What are the 3 classifications that diseases fall into?

A
  1. 100% environmental
  2. Single gene
  3. Polygenic

*genetically determined; environmentally determined; 1+2 types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is Genetic diseases?

A
  1. Rare
  2. Genetics simple
  3. Unifactorial
  4. High recurrence rate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is Environmental diseases?

A
  1. Common
  2. Genetic complex
  3. Multifactorial
  4. Low recurrence rate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are 5 classifications of genetic disorders?

A
  1. Chromosomal aberrations
  2. Multifactorial (Polygenic)
  3. Single gene (Monogenic)
  4. Somatic mutations (cancer)
  5. Atypical Inheritance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is Euploidy?

A

Normal 46 chromosomes (2n)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is Polyploidy?

A
  1. Spontaneous abortion

2. Change in the Genome copy number (3n or 4n)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is Aneuploidy?

A
  1. Caused by nondisjunction

2. Changing one chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is Trisomy numerical abnormalities?

A
  1. Compatible with life

2. (2n+1)=47

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is Monosomy numerical abnormalities?

A
  1. (2n-1)=45
  2. Two types:
    a. Autosomal (incompatible with life)
    b. Sex chromosomal (compatible with life)
  • Abnormalities of sex chromosomes are better tolerated than autosomal
  • Loss of chromosomal material is more dangerous than gain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are 8 types of Chromosomal aberrations?

A
  1. Down Syndrome
  2. Edward syndrom
  3. Patau syndrome
  4. Klinefelter syndrome
  5. Turner syndrome
  6. Cri du chat syndrome (5’ deletion)
  7. Angelman syndrome
  8. Prader-willi syndrome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is polygentic disorders (multifactorial)?

A
  1. Most common
  2. Influence of multiple genes + environmental
  3. One organ system affected

Ex: Diabetes mellitus, Hypertension, Gout, Schizophrenia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is Monogenic Disorders?

A
  1. 1% of total live births
  2. Follow Mendelian type of inheritance
  3. Dominant/recessive pedigree patterns
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is Autosomal Recessive Inheritance Homozygotes?

A
  1. With two copies of the altered gene (autosomes) are affected
  2. Ex: Cystic fibrosis, Sickle-cell anaemia, Phenylketonuria, beta thalssaemia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is Autosomal Recessive Inheritance Heterozygote?

A
  1. With one copy of altered gene and second normal gene are carrier of the disease and have no symptoms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is Autosomal Dominant Inheritance Heterozygotes?

A
  1. With one copy of altered gene are affected

2. Ex: Polycystic kidney disease, neurofibromatosis, Huntington disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is Autosomal Dominant Inheritance Homozygotes?

A
  1. With both altered genes are generally die before reproductive age
17
Q

What is X-linked Recessive Inheritance?

A
  1. Males are more prone due to having only one “X”
  2. Males can’t pass the effected X allele
  3. Women are very rarely affected and are primarily heterozygous carriers

EX: Duchenne Muscular Dystrophy, Hemophilia, Bruton’s Agammaglobinemia

18
Q

What is X-linked Dominant Inheritance?

A
  1. Only one copy of the X allele is required to have the disease
  2. Both males and females can be affected
  3. Males are more affected; all his daughters will be affected, but not of his sons will be affected

EX: Fragile X Syndrome, Incontinentia Pigmenti

19
Q

What is Somatic Mutations?

A
  1. Alternations in DNA that occur after conception
  2. Can occur in all cells except germ cells (which are not passed down to children)
  3. These alterations usually cause cancer
20
Q

What is Atypical patterns of Inheritance?

A
  1. Don’t follow the rules of Mendellian pattern of inheritance
21
Q

What is Co-dominance?

A
  1. Type of Atypical pattern of Inheritance
  2. When two allelic traits that are both expressed in the heterozygous state
  3. Ex: Blood group AB: the A and B blood groups are codominant

*Incomplete dominance: red flower and white flower germinate creating a pink flower (phenotype mix)

22
Q

What is Pseudo-dominant Inheritance?

A
  1. When a woman is homozygous for an autosomal recessive disorder and the husband is heterozygous of the same disorder
  2. There is 1:2 ratio for the children to be affected
  3. It is not dominant but it looks like a dominant pattern

*Happens in recessive cases only

23
Q

What is Atypical inheritance of single-gene disorders?

A
  1. Maternal inheritance of mitochondrial mutation
  2. Atypical presentation for Autosomal Dominant defects
  3. Genomic Imprinting
  4. Mosaicism
24
Q

What is Mitochondrial Inheritance?

A
  1. Mitochondria comes from the mother
  2. mtDNA is small circular double stranded
  3. When disorder affects mitochondrial chromosome it affects the energy metabolism

Ex: Lebers hereditary optic neuropathy (LHON); Rapid Optic nerve death (blindness in young adult life)

25
Q

What is Anticipation?

A
  1. A genetic disorder
    displays an earlier age of onset and/or a greater degree of severity in successive generations of
    the family pedigree.
  2. The reason might be the gradual expansion of trinucleotide repeat within or near a coding gene

Ex: Huntington disease, CAG repeats, Myotonic dystrophy

26
Q

What is Pleiotropy?

A
  1. One gene control more than one phenotype
  2. Different symptoms in different parts of the body can be affected by just one gene
  3. Ex: Tuberous sclerosis, Cystic fibrosis, Sickle cell anemia
27
Q

What is Variable expressivity?

A
  1. Refers to the range of signs and symptoms that can occur in different people with the same genetic condition
    * In autosomal dominant polycystic kidney disease, some individuals have renal dysfunction at early adulthood while others have not
28
Q

What is Reduced penetrance?

A
  1. Certain autosomal dominant disorders in which some individuals show the sign and symptoms of the diseases while others are never clinically diagnosed (so called reduced penetrance)
  2. Might be due to:
    a. modifying effects of other genes
    b. interactions of the gene with environment factors
29
Q

What is Genomic Imprinting?

A
  1. Is a genetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner
  2. Inheritance process independent of Mendelian inheritance
  3. Is due to methylation and histone modifications in the chromosome

Ex: Angelman syndrome, Prader-Willi syndrome…

30
Q

What is Familial?

A

Transmitted in the gametes through generations