DrSam

DrSam Samuel Ofori-Agyekum is a medical Doctor/ AI in Medicine Researcher sharing ideas on Health, Education, Lifestyle and Purpose.

My primary focus is personalised or precision medicine. Content shared here are for educational purposes only. Medical Doctor
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13/06/2026

A dose of codeine that is safe and effective in a patient in London can be potentially fatal for a patient in Addis Ababa.

The reason is a single enzyme: CYP2D6.

CYP2D6 converts codeine into its active form — morphine. How quickly it does this depends on which variant of the CYP2D6 gene a person carries. In 1996, Eleni Aklillu et al published a finding that changed the field: approximately 29% of Ethiopians carry gene duplications that make them ultra-rapid CYP2D6 metabolisers — compared to less than 3% of European populations.

For an ultra-rapid metaboliser, standard codeine doses can produce dangerously high morphine concentrations in the bloodstream: respiratory depression, sedation, and in extreme cases, death — at a dose that would be unremarkable in the average European patient.

CYP2D6 is not just about codeine. It metabolises approximately 25% of all prescribed drugs, including tricyclic antidepressants, antipsychotics, beta-blockers, and several chemotherapy agents. All of them are affected.

Global dosing guidelines are built from studies conducted predominantly in European and East Asian populations. For the 29% of East Africans who are ultra-rapid metabolisers — and the distinct patterns in West, Central, and Southern Africa — those guidelines are a poor fit.

Pharmacogenomics for Africa is not a luxury. It is a patient safety issue.

2.4% of GWAS participants are of African ancestry, despite Africa being 17% of the world (Mills & Rahal, Nature Communi...
12/06/2026

2.4% of GWAS participants are of African ancestry, despite Africa being 17% of the world (Mills & Rahal, Nature Communications 2019.)

Africa makes up 17% of the global population.
But African-ancestry individuals make up 2.4% of participants in genome-wide association studies.

That gap, identified in a landmark 2019 systematic review by Mills and Rahal, is not a bureaucratic footnote. It has direct clinical consequences for every African patient whose physician uses a risk score, a dosing chart, or a diagnostic panel built from the genomic evidence base.

GWAS studies identify genetic variants associated with disease. When the datasets are overwhelmingly European, the variants flagged as clinically significant are the ones most common in European populations. African-specific variants, which, given Africa’s greater genetic diversity, are more numerous; are simply not found.

The result: polygenic risk scores for cardiovascular disease, type 2 diabetes, and cancer underperform significantly in African patients. Drug dosing guidelines calibrated on European pharmacogenomic data prescribe wrong doses for populations with different metabolic enzyme frequencies. Diagnostic panels regularly miss pathogenic variants that are common in African populations but absent in European databases.

The data gap is not just an academic problem. It translates directly into suboptimal and sometimes dangerous care.

Closing it begins with investing in African genomic research at scale.

HELIX

Africa contains more genetic diversity than the rest of the world combined. You may have heard this before, and it is tr...
11/06/2026

Africa contains more genetic diversity than the rest of the world combined. You may have heard this before, and it is true.

That isn't a figure of speech. It is a documented scientific fact.

When University of Pennsylvania’s Prof of Genetics Sarah Tishkoff and colleagues studied 121 African and non-African populations in 2009, they found that Africa harbours more than 90% of all known human genetic variation. The 1000 Genomes Project later confirmed that Africa contains at least 14 distinct ancestral population clusters — more than all other continents combined.

This diversity is the product of time. Our species originated in Africa roughly 300,000 years ago and spent most of our evolutionary history here. The migrations that populated the rest of the world were founded by small subsets of African genetic diversity. So every other population on Earth is, genetically, a subset of what exists on the African continent.

The implication for medicine is enormous: the genetic architectures behind disease risk, drug metabolism, treatment response, and inherited conditions in African populations are the most varied and, right now, the least understood.

Unfortunately, the African genome is the least studied and because of this, precision medicine built on non-African data becomes precision medicine for some, not precision medicine for all.


This week, we explore 7 of the most important real-world implications of African genomic diversity, backed by peer-reviewed science.

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