Over the last 5 years, new actors involved in the pathogenesis of combined pituitary hormone deficiency in humans have been reported: they included a member of the immunoglobulin superfamily glycoprotein and ciliary G protein-coupled receptors, as well as new transcription factors and signalling molecules. New modes of inheritance for alterations of genes encoding transcription factors have also been described. Finally, actors known to be involved in a very specific phenotype (hypogonadotroph hypogonadism for instance) have been identified in a wider range of phenotypes. These data thus suggest that new mechanisms could explain the low rate of aetiological identification in this heterogeneous group of diseases. Taking into account the fact that several reviews have been published in recent years on classical aetiologies of CPHD such as mutations of POU1F1 or PROP1, we focused the present overview on the data published in the last 5 years, to provide the reader with an updated review on this rapidly evolving field of knowledge.

Over the last two decades, the understanding of the mechanisms involved in pituitary ontogenesis has largely increased. Since the first description of POU1F1 human mutations responsible for a well-defined phenotype without extra-pituitary malformation, several other genetic defects of transcription factors have been reported with variable degrees of phenotype-genotype correlations. However, to date, despite the identification of an increased number of genetic causes of isolated or multiple pituitary deficiencies, the etiology of most (80-90 %) congenital cases of hypopituitarism remains unsolved. Identifying new etiologies is of importance as a post-natal diagnosis to better diagnose and treat the patients (delayed pituitary deficiencies, differential diagnosis of a pituitary mass on MRI, etc.), and as a prenatal diagnosis to decrease the risk of early death (undiagnosed corticotroph deficiency for instance). The aim of this review is to summarize the main etiologies and phenotypes of combined pituitary hormone deficiencies, associated or not with extra-pituitary anomalies, and to suggest how the identification of such etiologies could be improved in the near future.