Genetics 6 (Genetic Disorders) Flashcards
What are the three types of obesity?
- Syndromic
- Monogenic
- Common
What is syndromic obesity commonly accompanied by?
- Mental Retardation
- Dysmorphic features
What is the action of leptin?
- Leptin produced by adipocytes in white adipocyte tissue
- travels to brain to let it know how much fat is stored in the adipose cells
- regulates feeding
What is the treatment for leptin deficiency?
Recombinant leptin
What are Genome Wide Association Studies and what are they used for in relation to obesity?
- hypothesis free
- common disease, common variant
- identifies single nucleotide polymorphisms associated with obesity e.g. FTO
What is an allele?
alternate form of gene
What is a mutation?
heritable change in DNA sequence
What is a polymorphism?
mutation a >1% frequency in given population
How do heritability estimates vary?
- between populations
- across ages
- sampling variance
- baseline risk of disease in population
What is monogenic diabetes?
- born with it and always going to develop diabetes
- single gene defect
What is polygenic diabetes?
- compilation of genetic changes that increase predisposition to developing diabetes
- dependent on environmental/lifestyle factors and genetic risk
What are the symptoms of monogenic leptin deficiency?
- hunger
- obesity
- no puberty
- poor growth
- low thyroid
- immune problems
What are some examples of monogenic and polygenic diabetes?
- monogenic: MODY, PND and mitochondrial diabetes
- polygenic: type 1 and 2 diabetes
What is the difference between a point and frameshift mutation?
- point = missense and nonsense
- frameshift = insertions/deletions
What are the features of monogenic disorders?
- caused by mutation
- clear inheritance
- no environment
- individually rare
What are examples of monogenic and complex disorders?
- monogenic: Huntington’s, CF and Haemophilia
- polygenic: T2D, schizophrenia and Crohn’s disease
What are the features of complex disorders?
- caused by polymorphisms
- no clear inheritance
- environment essential
- common
What is incomplete penetrance?
- symptoms not always present in individual with disease-causing mutation
What is variable expressivity?
disease severity varies between individuals with same disease-causing mutation
What is a phenocopy?
same disease but different underlying cause
What is epistasis?
interaction between disease gene mutation and other modified genes affects the phenotype
What is the clinical management of obesity?
- lifelong prevention and lifestyle measures
- medication
- bariatric (weight loss) surgery
