Week 1 - Genetics Flashcards
Give some examples of conditions that are autosomal dominant inheritance.
NF1, Achondroplasia, hypercholesterolaemia
Give some examples of Autosomal Recessive inherits conditions.
Cystic Fibrosis, sickle cell anaemia, PKU
Give examples of X-linked recessive inherited conditions.
Duchenne muscular dystrophy, Fragile X
Give examples of X-linked dominant inherited conditions.
Retts syndrome, Vitamin-D resistent rickets, incontinentia pigmenti
What are some conditions with genetic anticipation?
Huntington disease, fragile X syndrome, Myotonic dystrophy, spinocerebellar ataxia
What is an example of pseudo-dominant inheritance?
Gilberts syndrome
What is the difference between normal DNA and mitochondrial?
Normal: linear, double helix, in chromosomes, millions of genes, contains exons and introns.
Mitochondrial: Circular, smaller genome, 37 genes, no introns, 66% of genome coding DNA
What genetic condition is caused by a mutation in the base excision repair gene?
MYP polyposis (AR) (milder form of familial adenomatous polyposis - APC mutation, (AD))
What mutation causes Li fraumeni syndrome and what can it predispose to?
TP53 AD
Brain tumours, breast cancer, sarcoma, leukaemia, adrenal cortical carcinoma.
Give some characteristics of Edwards syndrome (trisomy 18)
Small chin, Malformation of heart, kidneys and other organs, clenched fists with overlapping fingers, cleft lip and palate, microphthalmia, abnormal ears
Give some characteristics of Patau syndrome
Congenital heart disease, 50% die within a month, 10% survive first year, generally with profound learning difficulties, cleft lip and palate, microphthalmia
What are some characteristics of Huntington disease (AD with genetic anticipation)
Age onset 30-50
Progressive chorea ,Dementia, Psychiatric problems, Problems swallowing and with co-ordination, lower weight
CAG repeat in coding region
What characteristics might you see in Myotonic dystrophy (AD with genetic anticipation)
Progressive muscle weakness adult onset
myotonia, cataracts
CTG repeats in translated but untranscribed (downstream region) of DMPK gene. Abnormal DMPK mRNA - indirect toxic effects on splicing
CF is AR with CFTR mutation at e.g. F508del. what are some features?
Recurrent lung infection, exocrine pancreatic insufficiency - (increased thickness of secretions)
Test via immunoreactive trypsin level and sweat testing
What is neurofibromatosis type 1
AD - NF is a tumour of the myelin sheath Diagnosis: > 6 café au lait patches Minimum of 2 skin neurofibromas 2 or more iris litchi nodules
What is the mutation in Duchenne muscular dystrophy
DMD gene Xp21
What areas might mitochondrial syndromes affect?
Muscle, brain, eyes
Allele specific (ARMS) PCR is a form of detecting point mutations, how does it work?
Detects a singe nucleotide substitution in a known position in a gene
What chromosomes are BRCA 1 and 2 on? (BRCA- repair ds breaks)
1 - 17
2- 13
What do TSG usually do? Loss of function
Inhibits the progression through the cell cycle.
Promote apoptosis
Act as stability genes
(MLH1, MSH2, APC)
What do promo-oncogenes do? Gain of function
Stimulate the cell cycle (MYC gene), the normal response to GF
What is the difference between the TSG and porto-oncogene?
P-O - only requires 1 allele to be mutated
TSG - both alleles must be mutated - Knudsen’s 2 hit hypothesis
What is cancer predisposition syndrome?
Genetic mutation that increases the chances of developing cancer at an earlier age compared to risk for general population. usually inherited AD mostly due to mutated TSG
In what inheritance pattern is consanguinity important?
AR
