Genetics Flashcards
On a pedigree chart what does the double line joining mean?
Consanguinity
On a pedigree chart, if you are unsure on the sex what do you represent the individual as? what if they are in utero?
diamond
P
How do you represent twins on a pedigree chart?
oblique line from generation above and joined with a double horizontal line
How many chromosomes, genes and base pairs do we have in each cell?
23 chromosomes, 23000 genes, 3.3 billion base pairs
Mitochondrial inheritance is passed how?
exclusively maternal
Example of cytogenetic testing?
FISH testing
Example of Molecular testing
DNA analysis - microarray, gene panels, exomes, whole genome
What is array CGH? what is it used for?
microarray comparative genome hybridisation
Used for chromosomal microdeletions
Features of Down’s Syndrome?
Single palmar crease Clustered facial features Stubby digits Small ears Slightly slanted eyes Sparce hair hypotonia Large tongue Small nose
What does nondisjunction mean in regards to cell division?
When some chromosomes dont make it to the right side of the cell
Apart from nondisjunction of chromosome 21, what is the other cause of Down’s Syndrome caused by abnormality in cell division?
Translocation of 21 onto 14 in mothers haploid
What is risk of reoccurence in trisomy 21 vs translocation of 21
trisomy = less than 1% Translocation = 50%
What trisomy causes Patau?
13
What brain abnormality occurs in Patau and how does this present at birth?
Hypotelorism - front of brain fused
Seizures
What defects does an individual with Patau syndrome suffer from?
Seizures Heart defect Renal dysplasia IUGR Polydactyly Early death
Where is the DiGeorge microdeletion and how is it diagnosed?
22q11 deletion diagnosed with microarray
What abnormalities do people with DiGeorge usually suffer from?
Cardiac abnormalities Thymus hypoplasia - hypocalcaemia, t cell dysfunction, infection Small chin Weird lips Broad nasal base Cleft palate Small sticky out ears
47 XXY? 47 X? Trisomy 18?
Kleinefelter
Turner
Edwards
Williams Syndrome deletion? what heart defect?
7q11 - supravalvular ventricular stenosis
Prader-Willi deletion?
15q11
Difference between Prader Willi and Angelman Syndrome?
Prader Willi is if its inherited from the male and Angelman is if its inherited from the female