Folates belong to the vitamin B group and are involved in a large number of biochemical processes, particularly in the metabolism of homocysteine. Dietary or genetically determined folate deficiency leads to mild hyperhomocysteinemia, which has been associated with various pathologies. Molecular mechanisms of homocysteine-induced cellular dysfunction include increased inflammatory cytokine expression, altered nitric oxide bioavailability, induction of oxidative stress, activation of apoptosis and defective methylation. Whereas the involvement of folate metabolism and homocysteine in ageing-related diseases, in several developmental abnormalities and in pregnancy complications has given rise to a large amount of scientific work, the role of these biochemical factors in the earlier stages of mammalian reproduction and the possible preventive effects of folate supplementation on fertility have, until recently, been much less investigated. In the present article, the possible roles of folates and homocysteine in male and female subfertility and related diseases are systematically reviewed, with regard to the epidemiological, pathological, pharmacological and experimental data of the literature from the last 25 years.

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The involvement of autoimmune mechanisms in premature ovarian failure has been put forward by numerous investigators. In various other ovarian pathologies, such as idiopathic infertility, polycystic ovary syndrome, or endometriosis, similar mechanisms have been suggested. However, the exact role of autoimmunity in the pathophysiology of these diseases still remains controversial. The diagnosis of autoimmune ovarian disease relies on several clinical, biological and histological findings, but special interest has been focused on antiovarian autoantibodies. The search for these antibodies has been undertaken by several authors and yielded somewhat conflicting results which might be conditioned by methodological differences and by the multiplicity of potential immune targets. These targets, which comprise various steroidogenic enzymes, gonadotrophins and their receptors, the corpus luteum, zona pellucida and oocyte, are reviewed. Further investigation of these targets is required to improve the diagnostic tools that will lead to a precocious and reliable diagnosis of autoimmune ovarian disease, an appropriate clinical surveillance as well as the selection of patients who may benefit from immune-modulating therapy and possibly recover ovarian function and fertility.

Classical galactosaemia is an inherited inborn error of the major galactose assimilation pathway, caused by galactose-1-phosphate uridyltransferase (GALT) deficiency. Many GALT mutations have been described, with different clinical consequences. In severe forms, newborns present with a life-threatening, acute toxic syndrome that rapidly regresses under a galactose-restricted diet. However, long-term complications, particularly cognitive and motor abnormalities, as well as hypergonadotrophic hypogonadism in female patients are still unavoidable. The pathogenesis of galactose-induced ovarian toxicity remains unclear but probably involves galactose itself and its metabolites such as galactitol and UDP-galactose. Possible mechanisms of ovarian damage include direct toxicity of galactose and metabolites, deficient galactosylation of glycoproteins and glycolipids, oxidative stress and activation of apoptosis. As there is no aetiological treatment, clinical management of ovarian failure in galactosaemic patients principally relies on hormonal replacement therapy to induce pubertal development and to prevent bone loss and other consequences of estrogen deprivation. Further investigations will be necessary to better understand the metabolic flux of galactose through its biochemical pathways and the mechanisms of these secondary complications. The aim of this article is to present an extensive review on the pathogenesis and clinical management of galactose-induced premature ovarian failure.

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