Excessive paternal transmission in psoriatic arthritis

Objective. The differential expression of a disease according to the sex of the disease-transmitting parent has been demonstrated in several autoimmun e disorders. The purpose of the present study was to determine whether ther e are differences in the transmission and expression of psoriatic arthritis (PsA) that are dependent on the sex of the affected parent. Methods. All probands (patients with PsA) were identified from among the pa tients attending the University of Toronto Psoriatic Arthritis Clinic. A se lf-reported family history of psoriasis or PsA was noted for each proband, Differences in parental and offspring transmission with respect to the prob and were evaluated, In addition, the expression of PsA according to the sex of the affected parent was assessed at the time of the proband's presentat ion to the clinic. Results, Ninety-five probands had affected parents: 62 (65%) had an affecte d father, and 33 (35%) had an affected mother, Thus, the proportion of pate rnal transmission (0.65) was significantly greater than was expected (0.5) (P = 0.001). Twelve of 74 offspring from male probands (16.2%) were affecte d with psoriasis or PsA, as compared with 9 of 108 offspring from female pr obands (8.3%) (P = 0.10), Probands whose fathers were affected had a higher frequency of skin lesions prior to arthritis (P = 0.047), an erythrocyte s edimentation rate >15 mm/hour (P = 0.044), and a lower incidence of rheumat oid factor (P = 0.044), No differences were noted with respect to age at th e onset of psoriasis or PsA, the severity of the PsA, or the frequency of H LA antigens, Conclusion. There appears to be excessive paternal transmission in PsA, Fur ther clinical confirmation and elucidation of its genetic basis is warrante d.