Genetics 6 Flashcards
What is the classification of obesity?
A BMI over 30.
What is the classification of morbid obesity?
A BMI over 40.
What is diabetes?
A constant state of hyperglycaemia due to either beta cell dysfunction or insulin resistance.
What are the features of type 1 diabetes?
- Present at any age
- Autoimmune system attacks and destroys beta cells
- Diminished or completely absent endogenous beta cell function
- Treated with insulin replacement
What are the features of type 2 diabetes?
- Onset is later
- Resistance to insulin, increases insulin production causing pancreatic exhaustion and eventual reduced secretion.
What does monogenic diabetes mean?
Only one gene causing it.
Examples of monogenic diabetes (3)
- MODY (maturity onset diabetes of the young)
- Mitochondrial diabetes
- Permanent neonatal diabetes
What is permanent neonatal diabetes?
- Very rare (1 in 400,000 babies)
- Diabetes in the first 6 months of life
- Often weened off insulin
What is mitochondrial diabetes?
- Maternally inherited via ovum
- Gives rise to maternally inherited diabetes and deafness (MIDD)
- MELAS
- Under diagnosed
What is meant by polygenic diabetes?
A compilation of genetic changes that increase predisposition to developing diabetes.
Examples of polygenic diabetes?
Type 1 and 2 diabetes
How are SNPs for certain disorders discovered?
Genome-wide association studies (GWAS)
What is HNF1-alpha?
A transcription factor that normally stimulates insulin production.
What is the outcome of mutated HNF1-alpa?
In MODY there is haplo-deficiency of these factors so less insulin is produced.
When do HNF1-alpha mutations become apparent?
Later in life when beta cell function begins to decline with age.
How are HNF1-alpha mutations treated?
Best with sulfonylureas.
What is glucokinase?
An enzyme that converts glucose into glucose-6-phosphate in glycolysis, eventually leading to insulin secretion.
What happens in the case of a glucokinase mutation?
Results in a higher set point at which insulin is secreted, so that individuals have a constant state of mild hyperglycaemia. Treatment is rarely needed.
Whats the difference between a germ-line and somatic mutation?
Germ-line mutations occur in gametes and can be passed onto offspring (entire organism is affected) whereas somatic mutations occur in a single cell body and cannot be inherited (only derivatives of cell are affected).
What are the risks associated with increased paternal age?
- Autism
- Schizophrenia
- Rare birth defects
- Miscarriage
- Childhood acute lymphoblastic leukaemia
What are the risks associated with increased maternal age?
- Down syndrome/chromosomal abnormalities
- Miscarriage
