Endocrine Abstracts

Growth is an inherent property of life. Normal somatic growth requires the integrated function of many of the hormonal, metabolic, and other growth factors involved in the hypothalamo-pituitary-growth axis. Discovery of transcription factors responsible for pituitary cell differentiation and organogenesis has had an immediate impact on understanding and diagnosis of pituitary hormone deficiencies. Importantly, combined pituitary hormone deficiencies (CPHD) have been associated with mutations in transcription factor coding genes that control organogenesis or multiple cell lineages, whereas isolated hormone deficiencies are often caused by transcription factors controlling late cell differentiation.

These transcription factors, mainly found and described primarily in transgenic and naturally occurring murine models, include factors such as HESX1, PROP1, POU1F1, LHX3, LHX4, TBX19, SOX2 and SOX3. Importantly, the expression of these various transcription factors dictates the phenotype that results when the gene encoding the relevant transcription factor is mutated. The highly variable phenotype may consist of isolated hypopituitarism, or more complex disorders such as septo-optic dysplasia and holoprosencephaly. As mutations in any of those transcription factors are rare, it is clear that many genes remain to be identified, and the characterization of these will further elucidate the pathogenesis of these complex conditions.

Furthermore, a normal development of a gland does not mean that the normal function will be maintained, as GH-1 gene defects may end in CPHD as well. These findings are to be stressed and have an impact how these patients need to be followed in clinical practice.