Trigger 10: Obesity Genetics Flashcards
BMI=
weight in kg/ height in M2
centiles by age and sex are defined to pass through
18.5 BMI at the age of 18 in 6 populations
why should doctors be worried about obesity
- Cancer
- T2DM
- CVD
- Blood pressure
- Arthritis
- Mental health
BMI is not always part of
some CVD risk calculation methods
name a risk calculation for CVD that does not included BMI
framingham risk score of fatal cardiovascular events
what does framingham risk score of fatal cardiovascular events take into account
cholesterol, systolic blood pressure, age, sex and smoking status
weight and height are highly
polygenic
polygenic
traits controlled by two or more genes
the obesity epidemic is 100% down to
environment and not genetics
why is the obesity epidemic completely related to the environment
we cant change our genetics (at least not at the rate at which he obesity epidemics arisen), but we can change the environemnt
example of ways the government has tried to change the environment
sugar tax
sugar tax is predicted to prevent how many cases of child obesity per year
95,000
poverty and poorer education are
markers of higher obesity
well educated and poor educated people
but on weight as they age at the same rate as those from deprived background (e.g. same BMI change per year)
what have been found not to work
anti-obesity programmes
one anti-obesity programs involved
54 birmingham schools
how many children involved
1467 year 1 pupils
how long was the intervention
12 moths
what did the intervention involve
30 mins a day extra activity
findings
no difference between BMI at 15 and 30 months
there is also evidence that..
education based intervention in children don’t change BMI (meta-analyses have shown- think of forest plot)
what causes obesity
increased obesity and T2DM in the 20-21st century cannot be due to changing genes- must be to do with environment
example of people affected by obesity
the Pima indians
the Pima indians
used to be a slim race, but now have a high prevalence and incidence of obesity
–> hypothesised to be caused by a change in environment
BMI is
heritable- more so than the public perception
what can be used to look at the heritability of BMI
twin, family and adoption studies
what have twin, family and adoption studies shown
that 50% of variation in BMI is due to eugenic variation
dizygotic twins
differences in genetics is evident in differences in height
monozygotic twins
similarity of genetics is evident in similarity of height
the strength of the genetic component to BMI
is not getting smaller in todays environmental
bell curves of identical twins
closely overlapping (nearly on top of each other)
bell curves of non-identical twins
only slightly overlapping- like two mountains
distant relatedness is correlated with
BMI- suggests that 30% of variation in BMI genetic
BMI correlations and genomic relationship matrix show that
those with higher BMI correlations, also have stronger genomic relationships
siblings who share 60% of their genome are more similar in BMI than siblings sharing
40 of their genome
therefore the more genome that is shared
the more similar BMI
most common diseases are caused by
rare single gene forms (SNVs)
Name some diseases caused by monogenic mutations
- diabetes
- alzheimers
- breast cancer
- obesity
types of monogenic diabetes
neonatal
MODY
mutations associated with maturity onset diabetes
- HNF1a
- HNF1b
- HNF2b
- Glucokinase
mutations associated with neonatal diabetes
- KCNJ11
- ABCC1
alzheimers caused by mutations in what genes
PSEN1
breast cancer caused by mutations in what genes
BrCa1/2
obesity caused by mutations in what genes
MC4R
Leptin
name a disease related to mutations in leptin and MC4R
Prader Willi syndrome
