Familial Dysautonomia Workup

Updated: Sep 11, 2018
  • Author: Robert A D'Amico, MD, FACS; Chief Editor: Hampton Roy, Sr, MD  more...
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Workup

Laboratory Studies

DNA diagnosis is now available, and documentation of the IKBKAP mutation is the criterion standard to confirm the diagnosis. However, in a patient in whom this diagnosis is suspected, a tentative diagnosis can be made using a constellation of clinical criteria. Traditionally, 5 cardinal criteria should be present for a firm diagnosis.

Parents of Ashkenazi Jewish ancestry: Both parents should have a history of being of Eastern European extraction.

Absence of fungiform papillae on the tongue: The highly vascularized fungiform papillae on the anterior third of the tongue are absent resulting in a smooth and glistening tongue tip. See following image.

Absence of fungiform papillae on the tongue. The h Absence of fungiform papillae on the tongue. The highly vascularized fungiform papillae on the anterior third of the tongue are absent resulting in a smooth and glistening tongue tip.

Decreased deep tendon reflexes: In 95% of patients with familial dysautonomia (FD), knee jerks cannot be elicited.

Lack of axon flare following intradermal histamine: Histamine phosphate in a 1:10,000 dilution injected intradermally does not produce pain or an axon flare. See following image.

Lack of axon flare following intradermal histamine Lack of axon flare following intradermal histamine. Histamine phosphate in a 1:10,000 dilution injected intradermally does not produce pain or an axon flare.

No overflow tears with emotional crying: Normally overflow emotional tearing can be delayed until age 7 months, but Schirmer tear testing usually shows diminished baseline tear flow.