OBJECTIVE: Based on the reports of familial aggregation of fibromyalgia (FM) syndrome, we investigated its possible genetic linkage to HLA by studying multicase families.

METHODS: Forty Caucasian multicase families with a diagnosis of FM (American College of Rheumatology criteria) in 2 or more first degree relatives were investigated. Eighty-five affected and 21 unaffected members of 41 sibships were studied. Depression symptomology was assessed by Zung Self-rating Depression Scale (SDS). HLA typing was performed for A, B, and DRB 1 alleles and haplotypes were determine with no knowledge of the subjects diagnosis. We investigated genetic linkage to the HLA region by evaluating sibships in multicase families.

RESULTS: Sibship analysis showed significant genetic linkage of FM to the HLA region (p= 0.028). Subgroup analysis was also performed for 17 families where the proband was also noted to have depression (with an SDS index value > or = 60). We found that the presence of depression did not influence the observed results (p=0.22).

CONCLUSION: Our study of 40 multicase families confirms existence of a possible gene for FM that is linked with HLA region. Our results should be regarded as preliminary and their independent confirmation by other studies is warranted. Partially supported by a grant from the National Fibromyalgia Research Association.

J Rheumatol (1999 Feb) 26(2):408-12