Gsh-1 transcription is restricted to the central nervous system. Expression is present in the neural tube and hindbrain as two continuous, bilaterally symmetrical stripes within neural epithelial tissue. In the mesencephalon, expression is seen as a band across the most anterior portion. There is also diencephalon expression in the anlagen of the thalamus and the hypothalamus as well as in the optic stalk, optic recess, and the ganglionic eminence. Mutation of the Gsh-1 homeobox gene results in pleiotropic effects on pituitary development and function.
Homozygous mutants exhibit extreme dwarfism, sexual infantilism and significant perinatal mortality.
Moreover, the pituitary content of a subset of pituitary hormones, including growth hormone, prolactin and luteinizing hormone, is significantly decreased. The hypothalamus, although morphologically normal, is also perturbed in mutants. The Gsh-2 nonclustered homeobox gene is expressed within the developing forebrain, midbrain, and hindbrain. Gsh-2 transcripts are shown to be particularly abundant in the hindbrain and within the developing ganglionic eminences of the forebrain. At the physiologic level the mutants experienced apnea and reduced levels of hemoglobin oxygenation.