LAUSR

Anti-Mullerian hormone (AMH) is a member of the transforming growth factor-beta superfamily, which was originally identified as the factor responsible for mediating regression of the Mullerian duct in the male foetus. In the past two decades, a vast number of studies have explored its expression and roles in the adult female. It is now recognised as an important intra-ovarian regulator, being synthesised exclusively in granulosa cells of the ovarian follicles in the adult female and acting as a gate-keeper of follicular activation, growth and steroidogenesis. Its concentration in serum can now be measured using several commercially available assays and can serve as a biomarker of the functional ovarian reserve representing the follicular pool available for recruitment at any one time. More than twenty AMH assay methods and platforms are now available commercially, with the few most commonly used platforms exhibiting good correlations between them. However, the assays frequently differ in their numerical calibration, with no international AMH standard available to harmonise the calibration, although this continues to be under active investigation. This problem of the lack of standardisation across AMH assays is a major factor limiting establishment of threshold cut-offs for various clinical applications at the moment and is reviewed by Li et al. While serum AMH concentrations change with the age of the woman, with a general trend of decline as ovarian aging progresses, the age-specific profile of AMH also differs between ethnicities. Studies reviewed by Kotlyar and Seifer generally found higher age-specific AMH concentrations in Caucasians compared with African-American Black and Hispanic women, as well as Chinese women above the age of 25 years. Such ethnic specificity should be taken into consideration when considering clinical outcomes, particularly if ethnic specific differences in that outcome exist. Recently, it has been recognised that AMH exists in multiple molecular isoforms, including proAMH, AMHN,C, AMHN and AMHC. The relative abundance of the various isoforms differs between similar-sized follicles of the same woman, and even between the follicular fluid and granulosa cells within the same follicle, as reported by Mamsen et al. This poses a further potential challenge in the