Fungiform Papilla Number and Olfactory Threshold Assessment in Males With and Without Barth Syndrome

Barth syndrome is a rare X-linked genetic disorder caused by a mutation or deletion of the tafazzin gene. Approximately 50–70% of affected males have family-reported feeding issues that affect eating habits and/or restrict dietary intake. Research to date suggests that these feeding problems may be related to differences in responsivity to taste and smell stimuli. The purpose of this study was to use indices of chemosensory function to study differences in food-related sensation and anatomy in males with and without Barth syndrome.

A cross-sectional two-group comparison design was used. Participants included 34 males with Barth syndrome between 5 and 34?years of age and 34 age-matched controls. Measures included the number of fungiform papillae on the anterior dorsal surface of the tongue and scores on the Sniffin’ Sticks olfactory threshold test.

Fungiform papilla counts did not differ significantly between males with and without Barth syndrome, suggesting that altered oral anatomy does not contribute to reported taste and feeding problems in this population. Olfactory thresholds significantly differed between groups; the Barth syndrome sample had a lower threshold for odor detection, indicating greater olfactory sensitivity. These objective measures match self-report data from the Barth syndrome population indicating that they perceive themselves as having a heighted sense of smell compared to others.

This study supports previous behavioral research indicating that olfactory sensitivity is heightened in the Barth syndrome population. Although differences in oral anatomy did not occur, previous research suggests that specific oral sensory cues (e.g., bitterness, texture) may be especially salient in Barth syndrome.

Since this is the first study to identify differences in odor threshold in the Barth syndrome population, findings should be corroborated with future research. These efforts should include odor, taste, and tactile cues at both threshold and suprathreshold concentrations. Results suggest, however, that interventions to address feeding and dietary needs of the Barth syndrome population should consider how food-related stimuli can be modified in order to facilitate appetite and reduce food refusal.