Student Presentations Flashcards
What is Familial Adenomatous Polyposis?
Polyps precursor to colorectal adenocarcinoma
Multiple adenomatous polyps
When polyps become large they cause blood in faeces
What are the three types of FAP?
Hyperplastic, Pedunculated and sessile
What pathway is involved in FAP?
APC/Wnt
APC complex dissociates from membrane and binds Beta catenin which is labelled by ubiquitin for degradation and prevents transcription. When the Axin binds to the LRP intracellular protein (bound to Wnt) the Beta catenin is free to initiate gene transcription.
What kind of mutations can cause FAP?
Oligomerization Armadillo repeats Beta catenin binding sites Axin binding sites Germ line mutations Somatic mutations
How is FAP managed and prevented?
Genetic screening
Genetic counselling
Surveillance
Surgery
How is FAP treated?
Proctocolectomy with ileal pouch anal anastomisis
Subtotal/Total colectomy with ileorectal anastomosis
Total proctocolectomy with ileostoy
What mutations are needed for the polyps to cause cancer?
K-ras and P53 mutations
What are some current research areas for FAP?
Wnt-based therapies
Extracolonic manifestations
Medical and surgical techniques
What is cystic fibrosis?
A monogenic disorder from CFTR mutation causing errors in chloride ion movement across the apical membrane and changes in electrical potential and other ion movement.
What are the symptoms of cystic fibrosis?
Excess mucus through exocrine organs
Salt imbalance
Affects respiratory, digestive and reproductive systems.
How do you diagnose cystic fibrosis?
Clinical features and sweat testing i.e. analysis of saltiness and chloride ion concentration
Genetic diagnosis
What are some cystic fibrosis treatments?
Physiotherapy Pulmonary rehabilitation Antibiotics and bronchodilators Gastrointestinal treatment Counselling Gene therapy CFTR pharmacotherapy
What is neurofibromatosis?
A disease which involves a genetic mutation (NF1/NF2) causing tumours hanging off or under the skin and causes blindness and sometimes death.
What are vesticular nerve schwannomas?
Distinctive feature of NF2, benign neurofibromas, characteristic of schwannomatosis which is the third form of neurofibromatosis.
What are the genetics of NF?
Autosomal dominant
Mutations within the NF1 gene on chromosome 17 and NF2 on chromosome 22.
Premature STOP codon in NF1 encodes inactive neurofibromin which doesn’t inhibit RAS P21 and allows proliferation.
What are some treatment options for NF?
Radiotherapy Surgery to remove tumours Gleevec Tyrosine kinase inhibitors Anti-angiogenesis therapies
What is alpha thalassemia?
Deficient alpha globin chain synthesis
Excess beta globin chains
Can be 1, 2, 3 or 4 deletion thalassemia
What is beta thalassemia?
Decreased beta globin chain production
Beta+ means less beta globin
Beta0 means no beta globin
Can be carrier, reduction or no production
What is thalassemia major?
Defective gene from both parents
Severe anemia, defective growth, fragile bones, yellow skin
Treated with regular blood transfusions and iron chelation therapy
What is thalassemia intermedia?
Severe gene plus mild gene
Paleness and moderate anemia
What is thalasssemmia minor?
Carrier
Small red blood cells
What is Hb Barr syndrome?
Loss of all 4 alpha globin chains
Build up of excess fluid, anemia, heart defects, genital abnormalities
What is HbH disease?
Loss of 3 alpha globin chains
Mild-moderate anemia, yellow skin, bone deformities
What goes wrong to produce thalassemia?
Glycine and succinyl-CoA form ALA
ALA forms protoporphyrin
Protoporphyrin and iron make heme
Heme combines with globin to make hemoglobin
When this process is disrupted it causes thalassemia
What are the advantages of heterozygous thalassemia?
Carriers have malaria protection against all malaria types
Beta thalassemia heterozygosity provides protection against ischemic heart disease
What is CAH?
When an enzymatic deficiency impedes cortisol production which feeds into the adrenal pathway causing disease.
What are the genetics of CAH?
Gene duplication leading to inactive CYP21A1P 21-OH gene
MIsalignment
Small scale gene conversion
Unequal meiotic crossover
What are the population genetics behind CAH?
@common@ human autosomal recessive Alaskan eskimos Ashkenazi Jews Founder effect Bottleneck effect from WWII
How is CAH prenatally treated?
Dexamethasone
Synthetic steriod, prevents/reduces virilisation
What are the 3 levels of deficiency?
Salt-wasting (severe)
Virilising (moderate)
Non-classical (mild)
Severity correlated to 21-OH level
How is a prenatal diganosis made?
Autosomal recessive
Sampling of chorionic villus
Amniotic fluid testing (amniocentesis)
What are the genetics of huntingtons disease?
Tri-nucleotide repeat on chromosome 4
Huntingtin gene (Htt)
CAG - glutamine codon repeated to form a polyglutamine tract
When more than 36 CAG repeats on Htt - disease
Dominant
Sex independent
How is the CAG repeat expanded in huntingtons?
With age and disease progression
Cis and trans elements modify CAG repeat region stability
Mismatch repair genes (MSH2/, 3, 6)
During replication and transcription
What is the huntingtin protein involved in?
Nerve cells Development High brain activity tissues Chemical signalling Material transport Protein binding Apoptosis protection
What happens when the Htt is mutated?
Glutamine is a polar molecule so the excess glutamine causes hydrogen bond links between fragments causing fibrous aggregates to stick together
What are the symptoms of huntingtons?
Age of onset is 30 - 50 years Clumsiness Loss of balance Involuntary movements Cognitive impairment Mood swings Sleep impairment Increase in symptom severity with disease progression
How is huntingtons diagnosed?
Medical history Diagnosis by neurologist Direct anaylsis by counting CAG repeats CT and MRI to see caudate nuclei and putamen Unified huntingtons disease rating scale
How is huntingtons treated?
No cure
Treatment involves managing symptoms
Antipsychotics to relieve chorea and irratibility
Antidepressents for behavioural management
What is the prevalence of Fragile X Syndrome?
Males primarily affected with females mostly carriers
What are the characteristics of FXS?
Large ears, prominent jaw, long face, flat feet, large testes.
Retardation, delay in learning speech and motor skills
Autism, ADHD, impaired social skills, hand flapping, repeated behaviours
What is the genetic basis of FXS?
Excessive CCG repeats become methylated. FXS protein production inhibited and disease caused.
How is FXS diagnosed?
By testing to measure number and size of CCG repeats
How is FXS treated?
Symptoms treated
New research into Dampening mGluR pathway and preventing mRNA binding to DNA
What is Prader-Willi Syndrome?
Non-function paternal section, snoRNA cluster lost
Hypotonia
Weak muscle
Development delay
Obesity
Therapy for behaviour, mental health and growth
Environment control
High frequency of chromosome 15 abnormalities
What is Angelman Syndrome?
Non functional maternal section, UBE3a gene lost Development and speech delay Balance problems DNA methylation analysis Non-degenerative Physical, speech, balance therapy Antiepileptic medication Social training Possibly cured by turning on paternal UBE3a gene or increasing CaMKII
What is phenylketonuria?
Reduced tyrosine and increased phenylalanine levels due to PAH mutation
What happens when PAH is mutated?
Located on chromosome 12
Misfolding occurs, degraded by proteases
Classic or moderate PKU
Mutations in BH4 leads to HPA
What are the symptoms of PKU?
Mental retardation Mousy odour Light pigmentation Peculiarities of gait, stance and sitting posture Eczema Epilepsy
What are the symptoms of maternal PKU?
Malformations Congenital Heart Disease Growth Retardation Microcephaly Reduced learning ability Behavioural effects
How is PKU diagnosed?
Screened for at birth
Recommended to be retested two weeks after birth or if child is having intellectual or developmental issues
Guthrie test, Tandem mass spectrometry
What is the heterozygotic advantage for PKU?
Increased fertility and optimal birthweight
What is duchenne muscular dystrophy?
X-linked mutation in the gene that codes for dystrophin protein. Dominant in males. Absence of a functional dystrophin leads to degeneration of skeletal and cardiac muscle fibers.
What are some symptoms for DMD?
Toe walking Balance problems Cognitive delay Pulmonary function decline Wheelchair Lost ability to care for themselves Respiratory and heart failure
What are two theories for DMD?
Absence of dystrophin causes DCG (links actin to extracellular matrix) becomes dysfunctional, causing sarcolemmal instability and muscle fibre damage.
Absence of dystrophin causes excess calcium and water in mitochondria, mitochondria burst leading to muscle cell necrosis.
What are the genetics of DMD?
Deletion, duplication or point mutation in second largest human gene
X linked recessive
How is DMD diagnosed?
Prenatal screening
Multiplex PCR
Creatine Kinase high levels in plasma indicate muscular dystrophy
Muscle biopsy detects dystrophin
How is DMD treated?
Delivery of genes as therapeutic agents but multiple injections required for treatment of all muscles.
Stem cell therapy and exon skipping but this can disrupt functioning genes if incorporated into wrong place
What is Leigh syndrome?
A disease that impairs energy production in mitochondria. No ATP causes cell death, damaged tissues, impairments and developmental delays.
What are the genetics of Leigh syndrome?
Maternal inheritance - mutation in mitochondrial ATP6 gene. Substitution of T for C results in leucine to proline conversion
How is Leigh syndrome treated?
Dichloroacetate lowers blood acetate levels
EPI-743 increases antioxidants
Rapamycin reduces oxidative metabolism
Name the 3 stages of Leber syndrome and their symptoms
Pre-symptomatic: Pericapillary Telangiectasia Microangiopathy
Acute: Centrocecal scotoma, hyperaemia, optic swelling
Chronic: Increased acute symptoms
How do you diagnose LHON?
Blood test and eye examination.
What are the risk factors for ALL?
Radiation, benzene, genetic conditions, chemotherapy drugs, smoking, race, compromised immunity, viruses.
What are the symptoms of ALL?
Anaemia, blood clotting problems and serious infections
Increased abnormal lymphoblasts
What are the genetics of ALL?
Not inherited
Translocation, trisomy and aneuploidy
Linked to Down, Klinefelter, Bloom due to the abnormal chromosomes
What are the three phases of ALL treatment?
Remission induction
Consolidation/intensification
Maintenance
What are some treatment options for ALL?
Chemotherapy
Radiotherapy
Stem cell transplant
Targeted therapy
