Thursday 22 November 2007

Treatment of genetic diseases in a real world 6: Maturity Onset of Diabetes in the young (MODY)

WHAT IS MATURITY-ONSET DIABETES OF THE YOUNG (MODY)?
Maturity-Onset Diabetes of the Young or MODY affects 1-2% of people with diabetes, although it often goes unrecognised.
The 3 main features of MODY are:
Diabetes often develops before the age of 25
Diabetes runs in families from one generation to the next
Diabetes may be treated by diet or tablets and does not always need insulin treatment
WHY DOES MODY RUN IN FAMILIES?
MODY runs in families because of a change in a single gene which is passed on by affected parents to their children. We call this Autosomal Dominant Inheritance. All children of an affected parent with MODY have a 50% chance of inheriting the affected gene and developing MODY themselves.
WHY IS IT IMPORTANT TO RECOGNISE IT?
There are different types of MODY. By finding out which type of MODY a person has the most appropriate treatment for them can be determined.
Knowing the type of MODY a person has also means we can advise them about how their diabetes will progress in the future.
As it runs in families, it is important to advise other family members of their risk of inheriting it.
WHAT DIFFERENT TYPES OF MODY HAVE BEEN IDENTIFIED?
MODY is caused by a change in a single gene. 6 genes have been identified that account for 87% of UK MODY:
HNF1-a

Treatment for patients with HNF1-a
Patients with HNF-1a MODY are extremely sensitive to the blood sugar lowering effects of a group of drugs called sulphonylureas (SU). This is an example of pharmacogenetics in diabetes – a persons genes influencing response to treatment. SUs include drugs like Gliclazide, Glipizide, Glibenclamide, Tolbutamide. SUs work to stimulate the pancreas to produce insulin. Preliminary findings are that SU sensitivity in HNF-1a MODY is due to two factors: Firstly, an increased pancreatic response to SUs, and secondly an increased sensitivity to insulin compared with Type 2 diabetes.
Glucokinase
HNF1-b (including Renal Cysts and Diabetes (RCAD)

HNF4-a
IPF1

Neuro D1
Changes in these different genes lead to different types of MODY. There are still more genes to identify as 13% of MODY is not yet accounted for.
http://www.projects.ex.ac.uk/diabetesgenes/mody/ATHtalk.PPT

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