Genetic refinement of the hereditary neuralgic amyotrophy (HNA) locus at chromosome 17q25

Hereditary neuralgic amyotrophy (HNA) is an autosomal dominant, recurrent f ocal neuropathy. HNA is characterised by episodes of painful brachial plexu s neuropathy with muscle weakness and atrophy, as well as sensory disturban ces. Single episodes are commonly preceded by non-specific infections, immu nisations or parturition. Mild dysmorphic features and short stature are pr esent in some HNA families, but absolute co-segregation with HNA has not be en described. To refine the previously described HNA locus on chromosome 17 q25, we performed a genetic linkage study in five HNA families with differe nt geographic origins. Significant linkage was obtained with chromosome 17q 24-q25 short tandem repeat (STR) markers in three HNA families and suggesti ve linkage was found in the other two HNA families. Analysis of the informa tive recombinations in affected individuals allowed us to reduce the HNA li nkage interval to a candidate region of 3.5 cM.