Genetics Flashcards
What cancers does Li-fraumeni syndrome present with in a family and what gene is affected?
Characteristic mix of sarcomas and breast cancer
Germline mutations of the tumour suppressor gene TP53
What kind of genetic disorder is Neurofibromatosis Type 1?
Autosomal dominant
Mutation of 17q tumour suppressor gene
What symptoms do you need two or more of to diagnose NF1?
café au lait spots - 6 or more neurofibromas - 2 or more axillary freckling Lisch nodules (specks in iris) optic glioma thinning of long bone cortex family history
What are further symptoms of NF1?
Macrocephaly Short stature Dysmorphic features- “Noonan look” Learning difficulties Most have some, often subtle, 10% special schooling, 3% moderate MH Epilepsy Scoliosis Pseudoarthrosis of the tibia Raised BP due to renal artery stenosis or phaechromocytoma Neoplasia CNS (optic gliomas), endocrine
What investigations should be done in NF1?
MRI and/or CT scans PET scan Biopsy skin Genetic testing to confirm NF1 mutation BP spine for scoliosis tibia for unusual angulation visual acuity and visual fields educational assessment ask patient to report any unusual symptoms
What chromosome is affected by NF2?
22
What is the main presentation of NF2?
Acoustic neuromas
CNS and spinal tumours
Cafe au lait spots
What kind of genetic condition is tuberous sclerosis?
Autosomal dominant
What is the classic triad of symptoms in tuberous sclerosis?
Epilepsy
Learning difficulties
Skin lesions
Hamartomas on organs
What investigations should be done in tuberous sclerosis?
Neurodevelopmental testing EEG ECG Echocardiography Renal ultrasound, CT, or MRI Chest CT Cranial CT Cranial MRI Genetic testing Skeletal x-ray Colonoscopy Renal biopsy
What kind of genetic condition is myotonic dystrophy?
Autosomal dominant
What are the symptoms of myotonic dystrophy?
Bilateral late-onset cataract
Muscle weakness, stiffness & myotonia
Low motivation, bowel probs, diabetes mellitus
Heart block
Death post-anaesthetic a risk if not monitored
Learning difficulty
What is penetrance?
If the gene for a condition is present, the chances of developing the condition
How do X linked conditions affect a family tree?
Affect males but no male to male transmission
What are the three forms of superoxide dismutase found in MND?
SOD1 is located in the cytoplasm
SOD2 in the mitochondria
SOD3 is extracellular
SOD1 and SOD3 contain copper and zinc,
SOD2 has manganese in its reactive centre.
The genes are located on chromosomes 21, 6 and 4
