Cystic Fibrosis (CF) is a progressive, hereditary disease that primarily affects the lungs and digestive system. It is usually diagnosed by the age of two, and adult diagnosis is comparatively rare. Although cystic fibrosis can be diagnosed through blood tests, sweat tests, genetic or carrier tests, Ray et al have developed an alternate sweat test: an adhesive color-changing “sweat sticker” device that can collect and examine sweat, and does not have to be used under clinical settings.
Cystic Fibrosis – the disease
Cystic Fibrosis is an autosomal recessive disease that occurs due to a mutation in the Cystic fibrosis transmembrane conductance regulator (CFTR) gene in mucus-secreting cells. This causes the mucus to become thick and sticky, and build up, collecting bacteria. In the lungs, the mucus blocks the airway, causing cough, difficulty in breathing, recurrent infections, and even respiratory failure. This can lead to permanent oxygen dependence or death. Mucus can also block the flow of digestive enzymes from the pancreas to the intestines, which means that the body can’t absorb any nutrients from food. In male patients, Cystic Fibrosis can cause infertility.
While Cystic Fibrosis has previously been a disease with a low survival rate, medical advancements have significantly improved patient’s lifestyles and lifespan. Early diagnosis is a key factor in this development.
Types of Screening
Numerous tests have been developed to diagnose this disease. Newborns are usually screened for CF in the first few days of their birth through a blood test. Carriers can also be identified to confirm the risk of parents passing the disease to their children.
A distinctive feature of CF is the presence of an abnormally high concentration of chloride in their sweat. This is the basis for the sweat test, the “gold standard” test for CF diagnosis. It involves the application of a cholinergic drug Pilocarpine, along with an innocuous electrical stimulation to stimulate sweat production. This can be then collected and tested for chloride concentration. A drawback, however, is that the test can take a very long time, especially in newborns, since they don’t produce a lot of sweat.
The sweat sticker
Ray et al have published a study in the Science Translational Medicine journal regarding their new device: the “sweat sticker”. This is a soft adhesive device that can collect and analyse sweat without the use of needles or electrical stimulation. The devices’ fit against the skin reduces any leakage, making it quite efficient, especially in infants.
It works by changing color according to the level of chloride in the sweat. This color change can be monitored by capturing images on a smartphone camera as time progresses, terminating the need for a clinical setting and a trained professional. According to the article, the device has shown promising results in clinical validation studies, and the authors call for larger studies to check its potential further.