Occurrence of Hypopituitarism in Tunisian Turner Syndrome patients: familial versus sporadic cases

Objective: To explore unusual association between Turner Syndrome (TS) and Hypopituitarism in a Tunisian cohort. Methods: We reported 6 patients with TS associated to Hypopituitarism, including three familial cases except the fourth sister who showed only a TS phenotype. Biochemical analysis, resonance magnetic imaging and cytogenetic analyses were performed. Results: The average age of our patients was 17.2 years (11–31 years). They were all referred for short stature and pubertal delay, except for the fourth sister who presented spontaneous puberty with the integrity of the pituitary axis and the presence of an X ring chromosome. Karyotype analysis showed monosomy in 3 cases and a mosaic TS in the 3 remaining cases, including one patient with abnormal X chromosome structure. Somatotropic and corticotropic deficiencies were confirmed in 2 sporadic cases while the gonadotropic and thyrotropic axes were spared. In contrast; familial cases were consistently affected by the integrity of the corticotropic axis. MRI showed pituitary hypoplasia in all familial cases and pituitary stalk interruption syndrome in only one sporadic case. No correlation was found between the chromosome formula and the anterior pituitary involvement. Conclusion: Co-segregation of congenital Hypopituitarism with pituitary hypoplasia and X chromosome aberrations could imply a molecular anomaly of transcription factors responsible for the differentiation and development of pituitary cells such as PROP1, POUF1, Hesx1, Lhx3, Lhx4. The etiopathogenic link between X chromosome abnormalities and the occurrence of Hypopituitarism remains unclear; however, the progress of molecular biology may clarify the interrelation between transcription factors and sex chromosome segregation abnormalities.