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Flashcards in Genetics in clinical practice 1 Deck (11)
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1
Q

What is the difference between phenotypic heterogeneity and genetic heterogeneity

A

Phenotypic -different mutations in the same gene that can sometimes give rise to strikingly different phenotypes
Genetic - mutations at two or more genetic loci that produce the same or similar phenotypes

2
Q

Autosomal dominant condition

A

transmitted from generation to generation (vertical inheritance)
male and female equally affected, affected parent of either sex can pass onto both sons and daughters (variable condition, variable expression)

3
Q

What is penetrance

A

proportion of carriers who manifest phenotypic signs of conditions. Not all individuals who inherit a dominant disease mutation necessarily show signs of it e.g. cherubism, age specific penetrance

4
Q

What does tertralogy of fallot involve

A

narrow pulmonary valve, thick RV, large over riding aorta, ventricular septal defect

5
Q

For some autosomal dominant diseases, the parents may not present with symptoms but their children might. Why

A

Even if exclude non paternity, a parent could carry a small proportion of gametes (germline cells that harbour the same mutation

6
Q

Autosomal recessive

A

Male and female can equally be affected

Generally only members of single sibship/cousinss affected

7
Q

Compound heterozygosity give examples and define

A

Different allelic mutation in same genes/locus

e.g. sickle cell anaemia

8
Q

X linked recessive

A

only males related via the female line are affected, woman usually asymptomatic. Sons of affected male are not affected

9
Q

What happens during X inactivation

A

Only one X ussed per cell->dosage compensation_
Only X in each ccell sqitched off before blastocyst implants in female embryos. Female embryos are mosaic only expressing either paternal or maternall X but nost

10
Q

X linked dominant

A

Males and femaales affected (femaless

11
Q

X linked dominant example

A

Incontinentia pigmenti, Goltz focal dermal hypoplasia