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Flashcards in Complex/Non-Mendelian Inheritance Deck (19)
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1

List five examples of non-Mendelian inheritance

Linked inheritance
Intermediate phenotype
Incomplete penetrance
Genomic imprinting
Extranuclear inheritance
Anticipation

2

What is penetrance?

the frequency with which a trait is manifested by individuals carrying the gene

3

What is incomplete penetrance?

gene is not phenotypically expressed in all members of a population that have the gene

4

What are two examples of penetrance mechanisms?

Genetic modifiers (e.g. polymorphisms)

Environmental factors

5

What is genomic imprinting?

the inheritance of one working copy of a gene, either from the maternal or paternal sides

the other, non-functional gene, is 'silent' (turned off)

6

From which parent are mitochondria inherited?

the mother (none from father as sperm degenerate after fertilisation)

7

Why do mitochondria have an increased mutation level?

- no DNA repair system
- no protective protein e.g. histones
- damaged by oxygen free radicals

8

What is homoplasmy?

all mitochondrial DNA is the same (no disease)

9

What is heteroplasmy?

more than one type of mitochondrial DNA is present (increased amount of diseases caused)

10

Give an example of a condition caused by triplet repeat expansion

Huntington's disease (repetition of CAG triplet)

11

What is triplet repeat expansion?

repetition of a particular sequence of three nucleotides in the genetic code of an individual which can give rise to disease

number if repeats in the code can increase through the generations

12

What is UPD?

Uniparental disomy

where a whole chromosome pair comes from only one parent

13

Give two examples of conditions caused by UPD

Angleman Syndrome (maternal UPD of chromosome 15)

Prader-Willi Syndrome (paternal UPD of chromosome 15)

14

What are the clinical features of Prader-Willi Syndrome?

- hypotonia (decreased muscle tone)
- short
- obese

15

What are the clinical features of Angleman Syndrome?

- epileptic
- mental retardation
- awkward gait

16

What is uniparental diploidy?

where all 46 chromosomes come from one parent

17

What are two types of uniparental diploidy?

Gynogenic (maternal)

Androgenic (paternal)

18

What are the clinical features of an embryo with gynogenic diploidy?

- mass of embryo
- ovarian non-malignant teratoma

19

What are the clinical features of an embryo with androgenic diploidy?

- mass of placenta
- hydatidiform mole (molar pregnancy)