Familial dysautonomia: a diagnostic dilemma. chronic lung disease with signs of an autoimmune disease.

We present an 11-year-old girl with sensory and autonomic neurological dysfunction, and respiratory insufficiency caused by recurrent aspiration. The diagnosis of familial dysautonomia (FD) was confirmed by a missing axonal flare to histamine, miosis in response to conjunctival methacholine and homozygous polymorphic linked markers DS58(18) and DS159(7) on chromosome 9. Ashkenazi Jewish descent could not be ascertained by history. A variety of positive tests for autoantibodies were initially interpreted as evidence for systemic lupus erythematosus vs. overlap syndrome with pulmonary, cerebral, skin, and ocular involvement. The diagnosis of FD was delayed because of the rarity of this disorder in Germany (second case reported). We discuss possible explanations for the misleading immunological findings, including interference by antibodies binding to milk proteins used as blocking reagents in enzyme-linked immunoassays and circulating immune-complexes due to chronic aspiration pneumonitis.