Molecular analysis of LHX3 and PROP-1 in pituitary hormone deficiency patients with posterior pituitary ectopia

The cause of posterior pituitary ectopia associated with anterior pituitary hormone deficiencies is unknown. We describe children with combined pituit ary hormone deficiency (CPHD) or isolated GH deficiency. In all cases, magn etic resonance imaging examination revealed abnormal pituitary gland develo pment featuring ectopic posterior lobe location and frequently hypoplastic anterior lobes. Embryonic development of the pituitary requires the coordin ated expression of specific transcription factors. Mutations of the PIT-1 a nd PROP-1 transcription factors are responsible for CPHD in some patients w ith normally positioned posterior pituitaries. In mice, the Lhx3 LIM homeod omain transcription factor is required for both structural development and cellular differentiation of the pituitary gland. Thus, we hypothesized that mutations in one or both of the two human LHX3 isoforms are responsible fo r posterior pituitary ectopia associated with anterior pituitary hypopituit arism. Comprehensive molecular analysis of the LHX3 isoforms was performed to test this hypothesis. No loss of function mutations in the LHX3 gene wer e detected. In addition, analysis of PROP-1 did not reveal mutations that m ight cause this phenotype. These studies suggest that the abnormal processe s leading to the development of CPHD or GH deficiency associated with poste rior pituitary ectopia are not a result of aberrant LHX3 or PROP-1 function , but may be caused by defects at other gene loci.