Pituitary function and glucose tolerance in a family with a PAX6 mutation

PAX6 is a transcription factor involved in the regulation of eye and islet cell development in humans and has also been shown to be an early marker of the pituitary gland in mice. While some subjects with PAX6 mutations were found to have impaired glucose tolerance or diabetes in two previous studies, there has been no report of systematic pituitary function assessment in these patients.

The objective of this report was to assess pituitary function and glucose tolerance in five related patients with a heterozygous PAX6 mutation and an unusual ocular and neurological phenotype.

Pituitary function (static and dynamic exploration of the five ante-pituitary axes) and glucose tolerance (oral glucose tolerance test) were explored in all patients.

Glucose tolerance was normal in all patients. We found no obvious pituitary deficiency in four of the five patients. However, borderline cortisol levels were observed in three out of these patients, with subnormal values, at baseline and/or after stimulation test. Basal and stimulated cortisol levels were both more clearly diminished in one subject.

We report here the first complete pituitary function assessment, together with glucose tolerance evaluations, in five related patients with a PAX6 mutation. We cannot rule out subtle corticotrope deficiency induced by PAX6 mutation. The conflicting results with the literature about glucose tolerance could be explained by genotype/phenotype correlations.