EXCLUDING LINKAGE BETWEEN PANIC DISORDER AND THE GAMMA-AMINOBUTYRIC-ACID BETA-1-RECEPTOR LOCUS IN 5 ICELANDIC PEDIGREES

The GABA(A) receptor subunits are candidate genes for panic disorder b ecause the receptor is the site of action for the anxiolytic effects o f the benzodiazepines. We tested for linkage between a tetranucleotide repeat polymorphism at the GABA(A) beta 1 locus, located on chromosom e 4p13-p12, and panic disorder defined by DSM-III-R criteria in 5 Icel andic pedigrees. Both a narrow affection status (definite panic disord er and agoraphobia) and a broad one (including probable cases of these disorders) were tested. With the narrow definition, at a recombinatio n fraction of 0.00, the lod scores in the 5 pedigrees ranged from - 3. 240 to + 0.063, the total score across all 5 pedigrees being - 8.299. With the broad definition at the same recombination fraction, the indi vidual lod scores ranged from - 2.614 to - 0.489, with the total being - 8.089. Thus, linkage between panic disorder/agoraphobia and the GAB A(A) beta 1 locus in these pedigrees is exceedingly unlikely.