Toral Shah: Familial breast cancer – genomics and SNPs

Toral Shah, Co-Founder of South Asian Supernovas, posted on LinkedIn:

“FAMILIAL HEALTH – we all know that there is some inherited risk to diseases including breast cancer. But not everyone know their risk or that their diet and lifestyle can impact this risk.

Delighted to have been included with my Mum in Super drug magazine sharing familial health stories. Both Mum and I were diagnosed with breast cancer under the age of 50.  We have at least other 12 family members who have had breast cancer including my aunt (mum’s sister), mum’s cousins and aunts. Whilst I was the youngest person to develop breast cancer in the family aged 29, I have one other first cousin who has had breast cancer under 45. We have some sort of familial breast cancer risk but we don’t have any of the current known single breast cancer mutations.

5% – 10% of all breast cancers occur due to a known gene mutation. This means that you might inherit a faulty gene from one of your parents, increasing your risk of breast cancer and other cancers. Genes such as BRCA1 and BRCA2 which can increase risk of breast cancer up to 80%. However, 15 – 20% of breast cancer cases may be familial meaning that there might be a gene mutation or something we don’t know about which increases our risk of breast cancer.

There is evidence that incidence of BRCA gene mutations might be higher in some South Asian populations, and there seems different BRCA mutations in the different South Asian ethnicities. Indian and Pakistani populations seem to have more BRCA1 mutations whilst there are more BRCA mutations in Bangladeshi populations and the other South Asian populations.

A single nucleotide polymorphism, or SNP, is a change in a DNA sequence where one nucleotide is substituted for another. These variations are the most frequent type of genetic difference found in humans. SNPs have multiple functions: they can potentially increase the likelihood of developing certain diseases, aid in predicting a person’s response to specific medications, track familial inheritance of disease-causing variants, and serve as biological markers for identifying genes associated with illnesses.

My family has several SNPs that impact my risk of breast cancer and cancer; there about 300 SNPs identified in genes that are associated with an increased risk of breast cancer, particularly in younger women, who often develop more aggressive subtypes like triple-negative breast cancer, potentially indicating a need for different genetic markers compared to older women. However, despite only 12% of the world’s population being white, approx 88 – 93% of the current genomic data comes from this population. It would be great if we could identify some SNPs that occur at different frequencies in different ethnic groups, and understand how environmental , diet and lifestyle factors impact these SNPs.

We don’t know how these SNPs occur in different ethnicities and given that people from South Asian and Black communities experience poorer outcomes in breast cancer, due to later diagnoses, more aggressive subtypes such as triple negative breast cancer and lack of diversity in clinical trials, we do need to include more ethnicities in genomic data and risk factors.

In addition, we need to build trust with these communities and invite them into clinical research and genomic testing so that we have data that reflects the global population and understands different communities risks.

So what can you advise your South Asian and Black patients?

• Knowing your family history of breast cancer is really important as this can help doctors to decide whether you require additional screening at a younger age. This might include ultrasounds or other types of screening including MRI scans.
• Knowing how to self-check, and doing this regularly will also help with early diagnosis, which can lead to improved outcomes. Please do ensure that you and your family to ensure that they know how to self-check (see South Asian Supernovas) South Asian language videos)
• Please attend screening mammograms when they are invited.”