Taste and smell in familial dysautonomia

Familial dysautonomia (FD) is one of the classic diseases characterised by taste and smell abnormalities. However, these typical features are based on data obtained from two separate crude studies published in 1964. In the present study psychophysical-cognitive and reflex-like facial-behavioral responses to taste and smell, in nine patients with FD and 15 healthy controls, were recorded. Five taste stimulants were presented to both study groups, while a selection of common household odors was used for FD patients only. The patients with FD showed a markedly higher incidence of recognition failures for salty, bitter, sweet, and water stimuli than the controls, but rate of recognition of sour stimuli was almost identical in the two groups. Estimates by the subjects on a hedonic scale of 0 to 10 and facial display in FD indicated a relatively normal sensitivity to sour stimuli and to a lesser extent to bitter stimuli. Water, sweet, and salty stimuli evoked non-discriminatory responses. These findings indicate specific dyageusia rather than general ageusia. Smell was found to be normal. In children with taste and smell impairment, a systematic evaluative approach may help in planning palatable diets for adequate and comfortable nutrition.