Normal and abnormal development Flashcards
Entirely genetic disease
Either inherited or prenatally acquired defects of genes.
Multifactorial
Interaction of genetic and environmental factors.
Entirely environmental
No genetic component to risk of disease.
What are the diseases called that predisposing to tumours?
Pre-neoplastic conditions. (Crohn’s disease to colon cancer)
What term describes the lesions from which tumours can develop?
Pre-neoplastic lesions.
What is the permissive effect of diseases?
Allowing environmental agents that are non-pathogenic to cause disease. I.e. opportunistic infections.
Prenatal factors
- Genetic abnormalities
- Transplacental transmission of environmental agents (Fetal Alcohol Syndrome, maternal rubella infection)
- Nutritional deprivation (critical effects during fetal morphogenesis)
What is the Barker hypothesis?
Risk for a disease is programmed partly by nutritional deprivation in utero.
Examples of polygenic disorders
Breast CA
AD
DM
OP
Coronary atherosclerosis
HLA-B27
Ankylosing spondylitis
HLA-DR3, B8
Coeliac Disease
Haemophilia
X-linked recessive disorder.
Heterozygote advantage
Protection against environmental pathogens (Sickle cell disease in black people - protection against malaria)
Genetic abnormalities may be
Inherited
Acquired during conception or embryogenesis
Acquired during postnatal life
Inherited or prenatally acquired often lead to..
Congenital metabolic abnormalities or structural defects
Neoplasms
Postnatally acquired genetic abnormalities.
HOX genes
Homebox genes - highly conserved 183 base pair sequence. Their expression during embryogenesis follows the order in which they are arranged, thereby sequentially directing body axis formation.
Mitochondrial DNA
Circular double stranded conformation
High rate of spontaneous mutations
Few introns
Maternal inheritance
Genes in mitochondrial DNA encode for…
Enzymes involved in oxidative phosphorylation. Therefore problems are found in genes with high energy demands - muscle cells and neurones.
Examples of mitochondrial diseases
Familial mitochondrial encephalopathy and Kearns-Sayre syndrome.
Functional genetics
Biochemical abnormality is known - DNA sequence can be probed.
Positional genetics
Abnormality is not known - position to a well-known neighbouring gene that is on the same chromosome and will be inherited along.
Mutagens have two consequences
Affect embryogenesis: teratogenic
Tumour development: carcinogenic
Haptens
Very small molecules are not antigenic (too small on their own) bind to larger molecules i.e. proteins.
Diathermy
Thermal injury used in surgery to coagulate and arrest bleeding.