New study sheds light on why patients with FD struggle to gain weight

Our weight is influenced by a number of factors, including our diet, our exercise, and our genetic code. While obesity is a major public health problem, doctors have long recognized that being severely underweight also has deleterious risks.

Patients with familial dysautonomia have a single mutation in their genome that results in a whole host of medical issues. For some, it becomes frustratingly difficult to gain weight. Despite having a gastrostomy tube to supplement their caloric intake with liquid nutrition, they remain significantly underweight. The cause for this is unknown. But, a study of 12 patients with familial dysautonomia, performed in Israel in collaboration with the Center, might reveal some insights (read: here).

By measuring energy expenditure at rest, the team found that around half the patient population have a hypermetabolic state – meaning their bodies are burning more energy even when they are sitting relaxing. Next, they questioned what cause them to have a higher basal metabolic rate. They found a link between the severity of their lung disease and resting energy expenditure. This suggests that the increased work of breathing may be driving the higher energy demands.

Around half the patient population have a hypermetabolic state. The increased work of breathing may be driving the higher energy demands.

For quite a while the team had suspected that there were additional factors that accounted for why around 75% patients with FD tend to be underweight. They also noted that a number of patients weren’t taking in a sufficient number of calories.

This combination of reduced energy intake and increased energy usage appears to be behind why we see patients struggling to gain and maintain weight. Since patients have a pattern of restrictive lung disease, it is likely that the muscles have to work harder to move the stiff chest wall and allow air to enter the lung. Likewise, if the lung is chronically inflamed, the inflammatory response expends energy and can contribute to weight loss.

The results underscore the importance of a multidisciplinary care approach to FD. Some patients may need to work with a nutritionist to make certain their caloric intake is sufficient while at the same time work with a pulmonologist to lessen inflammation in the lung. Such an approach would eventually shift the energy balance back into an even equilibrium, so that there isn’t a net deficit.


The study was conducted at Sheba Medical Center in Tel Hashomer, Israel as part of an international collaboration. Lead author of the study, Dr. Bat-el Bar was supported by the Familial Dysautonomia Foundation to spend time at NYU’s Dysautonomia Center to train in FD research and clinical care.  She and her team are currently recruiting patients for the natural history study (read more: here)


Link to the paper: