Endometriosis is generally regarded as a benign disease but it does exhibit
some characteristics reminiscent of malignancy. This raises the possibilit
y that, like malignant diseases, the development of endometriosis may invol
ve the acquisition of somatic genetic alterations in genes that regulate ce
ll growth and differentiation. Studies over the past few years have substan
tiated this view with the identification of a variety of genetic abnormalit
ies usually only associated with malignancies. Our own studies have shown t
hat genetic alterations, as shown by loss of heterozygosity, are relatively
common in endometriosis implying that tumour suppressor gene inactivation
is likely to be involved in the proliferation and maintenance of all endome
triotic implants, We have also shown by DNA fingerprinting that endometriot
ic lesions found adjacent to ovarian cancers have a common lineage, reinfor
cing the compelling histological and epidemiological data that endometriosi
s is a precursor of endometrioid and clear cell ovarian cancers. It is now
well accepted that susceptibility to endometriosis may also involve an inhe
rited genetic component. Studies aimed at identifying the predisposing gene
s are still in their infancy but should eventually provide invaluable insig
hts into the pathology and aetiology of endometriosis.