Module 3: Lesson 10 – Application of Genomics to Non-Communicable diseases


Name: Michelle Ramsay
Affiliation: Sydeny Bremner Institute, University of Witswatersrand
Location: Johannesburg, South Africa

Professor Michèle Ramsay (PhD). Director of the Sydney Brenner Institute for Molecular Bioscience (SBIMB) and Professor in the Division of Human Genetics, University of the Witwatersrand (Wits), Johannesburg. Her research interests include African population genetic and epigenetic diversity and their role in diseases exacerbated by adverse lifestyle choices, including obesity, cardiometabolic diseases. Participates in genetic research into rare eye, skin and autoimmune diseases in African populations, including albinism, keratolytic winter erythema, glaucoma, scleroderma and rheumatoid arthritis. Co-editor of a book: Molecular Medicine for Clinicians (2009) Wits University Press. Supervisor to BSc(hons), MSc and PhD students and host to postdoctoral fellows. Co-PI of the Wits non-communicable disease Research Leadership Program (NIH funded). Principal Investigator of an NIH funded Collaborative Centre under the H3Africa Consortium for “Genomic and environmental risk factors for cardiometabolic diseases in Africans”, and Research Chair on Genomics and Bioinformatics of African populations and is President of the African Society for Human Genetics.

Common chronic diseases like diabetes, hypertension, stroke and asthma affect a large proportion of the population and are the result of genetic susceptibility in the presence of specific environmental factors or triggers. We refer to these diseases as multifactorial traits because two main factors are involved: the genes and the environment. They are also often referred to as non-communicable diseases (NCDs) because they cannot be passed on from one person to the next i.e. they are not infectious. NCDs have a genetic or inherited component. This lecture will explain multifactorial inheritance and the methods used to identify genetic variants that contribute to the “genetic risk” for the trait. Populations specific considerations will be discussed and their impact on the use of genetic risk markers for NCDs. Genome-wide association studies (GWASs) will be explained in the context of two study designs: 1. Case control studies (e.g. cases with diabetes and controls without diabetes) 2. Continuous traits (e.g. blood pressure, obesity). Cancer is an important NCD and was covered in week 9.

Learning Outcomes

  • List the components that contribute to the risk of NCDs
  • Explain the role of genetic susceptibility for NCDs to patients
  • Explain to a patient that individual genetic variant tests usually contribute a very small amount to the variability in the trait (e.g. blood pressure) or to the risk for developing the NCD (e.g. diabetes).
  • List the significant limitations of current genetic tests in estimating genetic risk for NCDs
  • Develop material including appropriate knowledge to provide the patient with advice to minimise their modifiable risk factors in order to improve their outcome or to delay onset of NCDs

Class Videos

Class Slides

Assessments: Pre-Class Exercise
Click for reading on Complex Disorders
Click for reading on Diabetes
Scenario: Thandi (38 years of age) has just heard that her mother, Nomsa (aged 58), has been diagnosed with type two diabetes (T2D). Thandi is concerned about developing T2D because her father (Thomas) was diagnosed when he turned 51 and now that he is in his late sixties, he has developed cataracts and has a had his big toe amputated because of gangrene. Thandi’s maternal aunt was diagnosed with T2D at the age of 56. Thandi is very overweight, in fact her Body Mass Index is 35, and she has an office job at a bank.

Question: What advice could a nurse give Thandi and why?
Discuss and recommend appropriate medical check-ups. How could Thandi find out if she is likely to develop T2D?
(e.g. What biochemical tests are available that a doctor could request to determine her risk?)
Discuss the limitations, potential benefits, disadvantages and appropriateness of genetic testing.
Highlight, preventive measures such as medication, diet or lifestyle changes which may help.

Class Exercise
a) Please review the Health Promotional Pamphlet below and adapt this information for your local population. Your health promotional material should contain some information about heritability or the genetics of the disease, diagnosis, causes of diabetes and any myths/misconceptions about the disease prevalent in your area.
*Please note, this document would need to be reviewed by a behavioral change specialist and other professionals involved in the prevention and treatment of diabetes. (8 marks) Click here for the Health Promotional Pamphlet
b) List two other NC diseases prevalent in your community or line of work that you would consider developing health promotional material for and highlight the genetic/heritability information you are likely to include in a health promotional pamphlet (2 marks)

Class Evaluation
See course evaluations section.

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