Scientists have identified two genetic mutations which they claim trigger hypertension in up to a third of patients suffering from a common cause of severe high blood pressure.

“The findings are a major step in understanding the causes of high blood pressure. These findings may lead to a genetic test for this common cause of severe hypertension,” said lead author Richard Lifton of Yale University.

Some five to 10 per cent of patients with severe hypertension have tumours of the adrenal gland that produce a hormone called aldosterone. Removing these tumors can cure this form of hypertension.

Sifting for clues by sequencing all of the genes from these tumours, and comparing their sequences to the patients’ normal DNA, the scientists found either one of two mutations of a single gene were found in 8 of 22 tumours studied.

They discovered that these mutations cause both aldosterone release and tumour formation by allowing the encoded protein, a potassium channel, to conduct sodium rather than only allowing potassium to pass through the channel.

In addition to causing these adrenal tumours, inherited mutations in the same gene were also found to be the cause of a rare familial form of severe hypertension.

The results underscore the value of whole exome sequencing, or decoding of all of a patient’s genes rather than just a few suspect gene targets, said Dr. Lifton.

“This gene was not on anybody’s list to sequence in an investigation of this disease. We really hit the jackpot,” he wrote in the ‘Science’ journal.

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