“How often do you get sweaty socks?” is not a question you might expect from your doctor - but it could be important in detecting Fabry disease, a rare condition with a serious impact on the kidneys.

“People with Fabry disease can show a low capacity to sweat or to tolerate high temperatures, so where I suspect it, I may ask how often they have damp socks, or whether they like hot holiday destinations,” says Professor John Sayer, clinical professor of renal medicine at Newcastle University, Institute of Genetic Medicine.

Symptoms of Fabry can be subtle and mimic those of other conditions. “Doctors have to be detectives when it comes to Fabry,” says Sayer. “That is why it is under-diagnosed and diagnosis is often delayed. A European study has shown that the average delay is 14 to 16 years.”

Fabry is also rare – estimates of prevalence vary but it may be 1 in 40,000 among men, lower in women – so many doctors have never seen it.

Fabry is a lysosomal storage disease, a rare genetic condition with no cure, caused by the lack of an enzyme that breaks down the Gb3 protein. The build-up of Gb3 causes progressive cell damage affecting many body parts.

Symptoms can include burning sensations, pain or numbness in hands and feet, headaches, vertigo, tinnitus, dark red spots on the body, fever, sweating too little or too much, intolerance to heat, abdominal pain, vomiting and diarrhoea and impaired hearing.

Over time, some patients develop more serious symptoms. Waste products accumulating in the kidney cells and the walls of blood vessels supplying the kidneys can lead to impaired kidney function and ultimately kidney failure.

“Symptoms are diverse and sometimes subtle, so doctors may not put them all together and parents may assume some in children are just 'growing pains',” says Sayer.

Once suspected, however, testing is easy, using an analysis of the enzymes in a drop of blood or by genetic testing. Treatment is also straightforward, using enzyme replacement therapy in the form of a fortnightly dose of the enzyme which breaks down the Gb3.

The treatment is effective in delaying the complications resulting from the original enzyme deficiency, but in most cases, some damage has already been done, so other treatments are given to deal with existing symptoms.

New treatments, called chaperone therapies, are being trialled in Europe that involve  treating selected patients with molecules that help the enzyme to become more active. “It's promising but only suitable for patients with a specific genetic make-up,” says Sayer.

Most people with Fabry, even if treated with enzyme replacement therapy, have some kidney damage by the age of 50 to 55, because Gb3 damages the tiny blood vessels in the kidneys. The heart muscles and nerves can also be affected.

“The typical lifespan of a Fabry patient is 58, but early treatment can make a difference,” says Sayer. “Awareness and early detection are important.”