Several infectious agents appear to be significantly associated with sarcoidosis but none of the known associations is specific enough to suggest a direct causative role.

Herpes simplex virus type 1 has also been proposed to play a causative role in people carrying the susceptible versions of the apoE gene.

This parallels our finding of a higher incidence among women, but does not necessarily imply a causative role of anal intercourse.

They are also believed to play a causative role in the vascular complications of diabetes mellitus.

Proving that a virus has no causative role can be difficult.

Their causative role has been established in some of these diseases but not all.

The Iotatorquevirus have also been linked with this syndrome but a causative role - if one exists - has yet to be established.

However, genetic, immunologic, infectious, and/or psychologic factors are thought to play some causative role.

Whether replicative senescence (Hayflick limit) plays a causative role in organismal aging is at present an active area of investigation.

The studies show associations that indicate further investigation is needed and do not necessarily prove that vitamin D deficiency has a causative role.