GPR101 is a G protein-coupled receptor putatively involved in growth regulation. Duplications of this gene and coinciding overexpression of GPR101 results in acromegaly and gigantism. This may be caused by downstream upregulation of hypothalamic GHRH and dysfunction of the growth hormone axis in the pituitary and hypothalamus resulting from baseline increased GPR101. In immunohistochemistry, GPR101 has membranous positivity in the hypothalamus, basal ganglia, and cerebral cortex in the central nervous system. References: N. Engl. J. Med. 371: 2363–74, PMID: 25470569; Acta Neuropathol Commun. 2016; 4: 56, PMID: 27245663