Evidence for genetic heterogeneity in hereditary neuralgic amyotrophy.

Hereditary neuralgic amyotrophy (HNA) is a rare autosomal dominant disorder characterized by recurrent episodes of severe arm and shoulder pain with weakness, atrophy, and sensory impairment in a brachial plexus distribution. Recent studies mapped the HNA locus to chromosome 17q25. Two pedigrees with clinically typical HNA in which markers from chromosome 17q25 do not cosegregate with the disease and in which lod scores do not support linkage to chromosome 17q25 were identified.