W15 54 congenital and genetic disease Flashcards
Causes of disease classification
Genetic - chromosomal, single gene, multi factorial
Environmental
What chromosome abnormalities are there?
Aneuploidy/polyploidy
Translocations (balanced/unbalanced)
Inversion
Duplication
Deletion/micro deletion
Marker (rare)
Mosaicism (rare)
What is aneuploidy and polyploidy?
Aneuploidy = abnormality of chromosome number
Polyploidy = (rare) wrong number of sets of chromosome
What is the difference between balanced and unbalanced translocations, and which is more likely to have an adverse effect?
Balanced = all chromosomes are there but in wrong place
Unbalanced = not all chromosomes are there - there might be some missing or some extra. Important because if balanced, all genes are present so less likely you will have a congenital abnormality because of it. So unbalanced have worse adverse effects.
Give examples of autosomal trisomies - 3 copies of a chromosome - an aneuploidy
Down’s syndrome - 3 copies of chromosome 21
Edward syndrome
Patau syndrome
What sex chromosome abnormalities are there?
Klinefelter (XXY) - causes ganadel insufficiency causing men to not go through puberty properly
XYY - extra Y chromosome
Turner (XO) - missing X chromosome - most common, mostly in females
XXX
(All will likely impact intellectual development causing a lower IQ)
What might chromosome 22q11 microdeletion cause?
Clearing, usually of the palate
Not very obvious
Can cause severe congenital heart disease, intellectual disability, mental health problems increased etc
What single gene disorders are there?
Autosomal dominant
Autosomal recessive
X-linked recessive
(Mendel’s theories)
Examples of some autosomal dominant conditions?
Familial adenoma tours polypodies
Gorlin syndrome (basal cell nervus syndrome)
Neurofibromatosis
Tuberous sclerosis
Osteogenesis imperfecta
Autosomal dominant inheritance
Know how to do a punnet square
Males and females affected - equally transmitted by both
No ‘skipped generations’
No carries of the disease, either homozygous dominant or heterozygous dominant
Autosomal recessive inheritance
Can be a carrier of the disease - have one allele for it but will not display symptoms
Need 2 copies of the recessive disease allele to display the disease
What is consanguinity?
Incest - marrying closely related people and being the offspring to these ancestors
What are some common autosomal recessive conditions?
B-thalassaemia - abnormal beta globin synthesis causing severe haemolytic anaemia
Sickle cell anaemia - abnormal haemoglobin (S haemoglobin) causing severe haemolytic anaemia
Cystic fibrosis
PKU
Tay Sachs
Difference between pedigrees/punnets of women carry vs men carrying X-linked recessive inheritance.
Mutant genes are on the X chromosome
Carrier females are unaffected since recessive
All men who inherit the mutation are affected
Can ‘skip’ individuals
Give examples of X-linked recessive diseases
Haemophilia A and B (factor VIII and IX deficiencies respectively)
Duchenne muscular dystrophy
Colour blindness
