Claimant appeals from a determination by the Workers’ Compensation Board that his multiple sclerosis disease was not aggravated by excessive heat in his work environment. Four physicians, three of them board certified in neurology, testified at the hearing that the heat exposure increased the symptoms, but did not worsen the underlying condition. The referee, however, felt bound by the written opinion of another physician, who did not testify, that the heat caused a worsening of claimant’s underlying condition, solely because this court had found that doctor’s opinion to je persuasive in another multiple sclerosis case. Abbott v. SAIF, 45 Or App 657, 661, 609 P2d 396 (1980). Not only lid Abbott not concern the issue of heat as a cause of worsening of multiple sclerosis, but the contribution of one Xpert’s opinion to the preponderance of evidence in one case has no bearing on the relative weight of the same Expert’s opinion in another case with a different mix of Jciedical opinions.

Claimant did not sustain his burden of proof.

Affirmed.