Genetics Flashcards
Most common chromosomal defect type in down’s
Non disjunction in 94%
Robertsonian translocation in 5%
Mosaicism in1%
genetics of Haemochromatosis
auto recessive
Rule about autosomal dominant Vs recessive
Autosomal recessive conditions are ‘metabolic’ - exceptions: inherited ataxias are ‘structural’ but recessive
Autosomal dominant conditions are ‘structural’ - exceptions: Gilbert’s, hyperlipidaemia type II
Genetics of Peutz-Jeghers syndrome
Auto dominant.
numerous hamartomatous polyps in the GI tract, with pigmented freckles on the lips, face, palms and soles..
.50% of patients will have died from another GI cancer by the age of 60 years
Genetics and features of myotonic dystrophy
Dystrophia myotonica -DM1
distal weakness initially
autosomaldominant
diabetes
dysarthria
Can have cateracts
Genetics of haemochromatosis
Autosomal recessive disorder of iron absorption / metabolism
HFE gene chromosome 6
Prognosis with Philadelphia translocation t(9;22)
GOOD in CML
BAD in AML + ALL
Molecular biology techniques blot plotting….
SNOW DROP
South NOrth West -ern blotting techniques
DNA RNA Protein
DiGeorge Syndrome mnemonic
It has a variable presentation however its features can be remembered with the mnemonic CATCH22:
C -Cardiac abnormalities
A - Abnormal facies
T - Thymic aplasia
Tetany hypocal due to paraThyroid
T-cell deficiency due to Thymus
C -Cleft palate
H -Hypocalcaemia/ hypoparathyroidism
22 - Caused by chromosome 22 deletion
What diagnosis for following translocations
11;14 8;14 9;22 14;18 15,17
11;14 -> 11 looks like a M -> Mantle
8;14 -> 8 looks like B -> Burkitt
9;22 -> 9 looks like flipped P -> Philadelphia
14;18 -> 4licular/ follicular lymphoma
15,17 -> well it’s none of the above :D -> it’s the long name Acute Promyelocytic Leukemia.
Polycystic kidney disease type 1 and 2 chromosomes
16 and 4
Homocysteinuria Vs cysteinuria
Both auto recessive
Homocyst isa disorder in metabolism of methionine,an amino acid, causing vitamin b12, b6 , folate deficiency
Cysteinuria is too much cysteine (amino acid) in urine, kidney stones
Genetics of congenital nephrogenic diabetes insipidus
X-linked mutation in the vasopressin (ADH) receptor gene (the more common form)
Autosomal recessive defect in the aquaporin 2 gene (the less common form)
Genetics of Marfan’s
FBN1 gene on chromosome 15 that codes for the protein fibrillin-1
HLA association with coeliac
I ate (8) too (2) much gluten at Dairy Queen - for Celiac Disease DQ8/DQ2
HLA association with rheumatoid arthritis
There are 4 walls in a ‘rheum’ (room) - for Rheumatoid A. HLA DR4
This is also asssx with T1DM, and less so DR3
HLA association for multiple sclerosis
Multiple Hay Pastures have DiRT - Multiple sclerosis, Hay fever, Goodpasture synd. for HLA DR2
genetics of achondroplasia
70-80% is from sporadic/spontaneous mutation, but following this it tends to be autosomal dominant
X-linked Dominant conditions
Alports (in 85%, the rest auto R, very rare auto D)
Rett Syndrome
Vit D resistant Rickets
will children of man with Alports have the condition?
X-linked Dom
So sons wont have it, daughters will
inheritance of mitochondrial disease
all children of male will NOT inherit
all children of female will inherit.
although poor genotype:phenotype correlation
muscle biopsy may show red ragged fibres (due to increased mitochon)
most common cardiac abnormality in Down’s
Endocardial cushion defect (AKA Atrioventricular septal canal defect)
Which LQT syndrome is associated with deafness?
Jowel and Lange-Nielson syndrome has profound deafness
RomaNO ward = NO deafness
ATP7B is the dysfunctional protein associated with…
… Wilson’s disease.
