Septo-optic dysplasia. de Morsier syndrome.
Incidence
Although most cases of pituitary hypoplasia are sporadic and idiopathic, a few sib pairs have been reported with SOD, suggesting a genetic basis in some cases, with an autosomal dominant mode of inheritance. The syndrome is rare, affecting less than 1 in 10.000 livebirths, and the phenotype is highly variable. Fully expressed septo-optic-pituitary dysplasia is a rare disorder. The precise incidence and prevalence are not known. The incidence of some of the component disorders, occurring in isolation, is much higher.
Clinical Characteristics
Septo-optic dysplasia (SOD) is a clinically heterogeneous disorder loosely defined by any combination of optic nerve hypoplasia, pituitary gland hypoplasia, and agenesis or hypoplasia of midline brain structures, including the corpus callosum and septum pellucidum. It is thought of a disorder of midline prosencephalic development. The symptoms, which occur especially when a disorder of cortical development is also present (SOD plus) consist of visual defects, endocrinological manifestations, developmental delay, motor deficits, and epileptic seizures. The syndrome is rare, affecting less than 1 in 10.000 livebirths, and the phenotype is highly variable. Sixty-two per cent of affected individuals have hypopituitarism and 30% have all three manifestations. Diagnosis usually relies on CT scan or MRI of the brain. Male often have micropenis and cryptorchidism, and hypoglycemia may be detected in the first hours of age. Pituitary dysfunction is the most common, revealed by growth hormone deficiency and failure of the pituitary to respond to thyrotropin releasing hormone. Transient hypocalcemia responds to calcium and vitamin D supplements. Most have corticotropin deficiency, with sometimes thermoregulatory disturbances, and others have diabetes insipidus. Sudden and unexpected death was reported in at least 5 children with septooptic dysplasia. In case of early diagnosis, when anterior pituitary hormone replacement therapy can be begun in the first week of life, patients may remain well subsequently. Severe psychomotor retardation was reported in some patients. All have short stature, but head circumference and weight are within normal limits. Although most cases of pituitary hypoplasia are sporadic and idiopathic, a few sib pairs have been reported with SOD, suggesting a genetic basis in some cases, with an autosomal dominant mode of inheritance. Heterozygous mutations in the HESX1 gene were found in a number of patients with relatively mild pituitary hypoplasia or SOD, which displayed incomplete penetrance and variable phenotype among heterozygous family members. Septo-optic dysplasia was also reported as a manifestation of valproic acid embryopathy : a newborn who was exposed to the drug in utero throughout pregnancy presented with features typical of valproic acid embryopathy, and MRI showed hypoplasia of the optic chiasm and absence of the septum pellucidum.
Precipitants
Septo-optic dysplasia has been reported as a manifestation of valproic acid embryopathy : a newborn who was exposed to the drug in utero throughout pregnancy presented with features typical of valproic acid embryopathy, and MRI showed hypoplasia of the optic chiasm and absence of the septum pellucidum.
Provocation Tests
There is failure of the pituitary to respond to thyrotropin releasing hormone.
Diagnostic Procedures
It is a clinico-radiological diagnosis.The cardinal features of septo-optic-pituitary dysplasia are early visual impairment (due to optic nerve hypoplasia) and hypopituitary dwarfism. Both features may occur together in some patients or separately in others. Diagnosis usually relies on CT scan or MRI of the brain.