ERVW1

ERVW1, also known as Syncytin-1, is a human gene derived from the envelope gene of the endogenous retrovirus HERV-W. It is located on chromosome 7q21.2 and, in humans, retains an intact open reading frame capable of producing the envelope glycoprotein Syncytin-1.

The Syncytin-1 protein mediates fusion of trophoblast cells to form the syncytiotrophoblast layer, a multinucleated tissue essential for placental formation and function. Its expression in placental tissue is developmentally regulated, and the protein also exhibits immunomodulatory properties that may contribute to maternal-fetal tolerance during pregnancy.

ERVW1 is part of the HERV-W family and stands as an example of a domesticated retroviral gene co-opted for a normal physiological role in placentation. Expression is predominantly in placental tissue, though the gene or its protein can be detected in other tissues under certain conditions.

Clinical relevance is most often discussed in relation to the HERV-W envelope protein in inflammatory contexts. Abnormal or elevated HERV-W Env has been reported in some conditions, notably multiple sclerosis, where it has been proposed to contribute to disease pathology, though a causal role remains unproven. Therapeutically, antibodies targeting HERV-W Env (such as temelimab/GNbAC1) have been investigated in clinical trials for MS, reflecting ongoing interest in the potential modulation of HERV-W–related pathways.

See also: HERV-W, Syncytin-1.