DNA study to change medicine in Africa

Professor Collen Masimirembwa believes that studying the genomic diversity in Africans can improve the way drugs are used to treat illness.

Medical advances have saved countless lives but there is always room for improvement, and Professor Collen Masimirembwa believes that studying Africans’ genomic diversity can make medicines more effective.

Professor Masimirembwa, who has two PhDs in biochemistry and genetics, specialises in gene drug interactions and has spent much of his career pioneering forensic DNA and toxicology in Africa.

He was the first to conduct molecular pharmacogenetic studies in African populations in 1993.

He spoke to doctors in various fields, at the Vineyard hotel in Newlands on Tuesday, about how a small difference in genetic make-up can have a huge impact on the treatment of HIV-positive patients with antiretrovirals (ARVs).

Genomic medicine studies genetic make-up to predict disease risk and progression and dictate how a specific patient will respond to certain drugs.

It can make a treatment more effective by gauging the dosage best suited to an individual patient.

Professor Masimirembwa said most medications came with leaflets warning of adverse side-effects if taken by people with certain genetic conditions. However the information wasn’t user-friendly and many didn’t know their genetic make-up, so they were unaware of whether the warning applied to them.

He cited the example of HIV patients with a HLA-B 57:01 variant in their DNA. They have a high risk of having a fatal hypersensitivity to the drug Abacavir. There are now more than 30 ARVs on the market and treatment is often a complicated cocktail of several different medications.

Genetic profiling helps doctors develop treatment plans and prescribe correct ARVs at appropriate doses to yield the best outcome. “All patients receive the same diagnosis, but some receive the benefit of the drug and the toxicity, and some receive toxicity without the benefits. How can we improve the medication to reduce toxicity?” he said, adding that 70% of hospitalisation was caused by serious adverse drug reaction.

“A pharmacogenomics test tells us your genetic status, and we can predict the effect of the medication on you. A blood sample will be used for a DNA test, which will show us your specific genome so that we can give you specific drugs and this will lead to a happy you,” said Prof Masimirembwa.

The genetic-profiling approach, he said, meant doctors could find the best ARV combination for a patient quickly, while avoiding costly trial and error.

It would also reduce the risk of bad drug reactions.

“Genetic studies will give doctors guidelines to help patients deal with their genetic status. Medicine dosage can be from 1mg to 20mg a day so how do we know which to give? We can’t take genetic testing from Europe and use it in Africa,” said Professor Masimirembwa.

He said Africa was making a late but promising entry into genomic research. In South Africa, mygeneRx, a cheek swab DNA test, can be ordered online and conducted in the patient’s home.

For more information about pharmaocenomic testing, visit www.mygeneRx.co.za. To speak to an expert about pharmacogenomics testing, email nicole@gullanandgullan.com