In this episode, our guests explore the impact of genetic discoveries on inherited retinal dystrophies, in particular retinitis pigmentosa (RP). The discussion highlights a recent study that identified two non-coding genetic variants linked to RP, predominantly in individuals of South Asian and African ancestry.

The conversation highlights how advances in whole genome sequencing are uncovering previously hidden causes of genetic disease, improving diagnostic rates, and shaping the future of patient care. It also addresses the challenges faced by individuals from diverse backgrounds in accessing genetic testing, including cultural barriers, awareness gaps, and historical underrepresentation in genomic research.

Our host Naimah Callachand is joined by researcher Dr Gavin Arno, Associate Director for Research at Greenwood Genetic Centre in South Carolina, Kate Arkell, Research Development Manager at Retina UK, and Bhavini Makwana, a patient representative diagnosed with retinitis pigmentosa and Founder and Chair of BAME Vision. We also hear from Martin Hills, an individual diagnosed with autosomal dominant retinitis pigmentosa.

To access resources mentioned in this episode:

• Access the Unlock Genetics resource on the Retina UK website


• Visit the BAME vision website for more information and support


• Find out more about the groundbreaking discovery of the RNU4-2 genetic variant in the non-coding region which has been linked to neurodevelopmental conditions in our podcast episode

"Discoveries like this lead to better clinical management. We understand better the progression of the disease when we can study this in many individuals from a wide spectrum of ages and different backgrounds. We can provide counselling as Bhavini was talking about. We can provide patients with a better idea of what the future may hold for their eye disease, and potentially, you know, we are all aiming towards being able to develop therapies for particular genes and particular diseases."

You can download the transcript or read it below.

Naimah: Welcome to Behind the Genes.  

Bhavini: The few common themes that always come out is that people don’t really understand what genetic testing and counselling is. They hear the word counselling, and they think it is the therapy that you receive counselling for your mental health or wellbeing. There is already a taboo around the terminology. Then it is lack of understanding and awareness or where to get that information from, and also sometimes in different cultures, if you have been diagnosed with sight loss, you know blindness is one of the worst sensory things that people can be diagnosed with. So, they try and hide it. They try and keep that individual at home because they think they are going to have an outcast in the community, in the wider family, and it would be frowned upon). 

Naimah: My name is Naimah Callachand and I am Head of Product Engagement and Growth at Genomics England.  I am also one of the hosts of Behind the Genes. On today’s episode I am joined by Gavin Arno, Associate Director for Research at Greenwood Genetic Centre in South Carolina, Kate Arkell, Research Development Manager at Retina UK, and Bhavini Makwana, patient representative.  Today we will be discussing findings from a recently published study in the American Society of Human Genetics Journal which identified two non-coding variants as a cause of retinal dystrophy in people commonly of South Asian and African ancestry. If you enjoy today’s episode, we’d love your support. Please like, share, and rate us on wherever you listen to your podcasts. 

Okay, so first of all I would like to ask each of the three of you to introduce yourselves. Bhavini, maybe we’ll start with you. 

Bhavini: Hi, I’m Bhavini Makwana, patient representative, and also Chair of BAME Vision. I have other roles where I volunteer for Retina UK, and I work for Thomas Pocklington Trust. 

Naimah: Thanks Bhavini. Gavin. 

Gavin: Hi, my name is Gavin Arno, I am Associate Director for Research at the Greenwood Genetic Centre in South Carolina, and I am Honorary Associate Professor at the UCL Institute of Ophthalmology in London. 

Naimah: Thanks Gavin. And Kate.  

Kate: Hi, I’m Kate Arkell, Research Development Manager at Retina UK.  

Naimah: Lovely to have you all today. So, let’s get into the conversation then. So Gavin, let’s come to you first. First of all, what is retinitis pigmentosa and what does it mean to have an inherited retinal dystrophy? 

Gavin: So, retinitis pigmentosa is a disorder that affects the retina at the back of the eye. It is a disease that starts in the rod photoreceptor cells. So, these cells are dysfunctional and then degenerate causing loss of peripheral and night vision initially, and that progresses to include central vision and often patients will go completely blind with this disease. So, retinal dystrophies are diseases that affect the retina. There are over 300 genes known to cause retail dystrophy so far, and these affect different cells at the back of the eye, like retinitis pigmentosa that affects the rods. There are cone rod dystrophies, ones that start in the cone photoreceptors, macular dystrophies that start in the central retina, and other types of retinal dystrophies as well. 

Naimah: Thanks Gavin. And Bhavini, just to come next to you. So, you received a diagnosis of retinitis pigmentosa at the age of 17 after a genetic change was found in the RP26 CERKL gene. At this time only ten other families in the UK had been identified with this type of genetic alteration. Would you mind sharing a bit more about your journey to your diagnosis? 

Bhavini: Yeah. So, at the age of 17 is when I got officially diagnosed with retinitis pigmentosa, but leading up to that I was experiencing symptoms such as night blindness. So, I struggled really badly to see in the dark, or just in dim lighting, like this time of the year in winter when it gets dark quite easily, all my friends from college could easily walk across the pavement, but I struggled. I was bumping into a lot of things. Like things that I wouldn’t really see now that I know my peripheral vision, I was losing that, so like lamp posts or trees or bollards, I would completely miss or bump into them. I was missing steps, and had a really, really bad gaze to the sun. Like, everything was really hazy. That continued and I just put it down to stress of exams. You know, just given that age and where I was at the time of my life. But then it kind of continued. So, I went to the see the optician who then referred me, and after months of testing I got diagnosed with retinitis pigmentosa. Back in the late 90s when I was diagnosed there wasn’t really anything about genetic testing, or cures., or treatments. I was basically just told to get on with it, and that was it.  

It was only until about 15/16 years later I came across Retina UK, started understanding what retinitis pigmentosa is, and what it means, and then when I was offered genetic testing and counselling at one of my annual Moorfields appointments, they explained to me what it involved, what it could mean, what kind of answers I would get, and I agreed to take part. It was a simple blood test that myself and both my parents took part in.     

Naimah: Thanks for sharing that Bhavini. So, I know you were able to receive a diagnosis through whole genome sequencing in the 100,000 Genomes Project after the alteration in the gene was found, and this was found in the coding region of the genome. But in this study that we are talking about in this podcast, we know that the two genetic changes that were found, they were in the non-coding region of the genome. Gavin, could you tell me in simple terms what the difference is between the coding and non-coding region of the genomes and why these findings are significant in this case?  

Gavin: Yes, sure. So, the human genome is made up of about 3 billion letters or nucleotides which are the instructions for life essentially. Now, within that human genome there are the instructions for roughly 20,000-25,000 proteins. This is what we call the coding genome. These are the bits of DNA that directly give the instructions to make a protein. Now, we know that that part of the genome is only roughly 2% of the entire genome, and the remaining 98% is called the non-coding genome. Now, we understand that far less well. We have a far poorer understanding of what the function of the non-coding genome is versus the coding genome. So, typically molecular diagnostic testing or genetic testing is focused on the coding genome, and historically that has been the fact. Now with advances in genome technologies like whole genome sequencing and the 100,000 Genomes Project, we are able to start to look at the non-coding genome and tease out the previously poorly understood causes of genetic diseases that may lie within those regions of the genes.  

Naimah: Thanks Gavin, I think you have just really highlighted the possibilities available with looking at the non-coding region of the genome.  Kate, coming to you next. I wanted to talk about the importance of uncovering and understanding genetic causes of inherited retinal dystrophies, and how do discoveries like these change the landscape