A Novel Variant c.97C>T of the Growth Hormone Releasing Hormone Receptor Gene Causes Isolated Growth Hormone Deficiency Type Ib.

Congenital isolated growth hormone deficiency (IGHD) type 1b is an autosomal recessive genetic condition caused by mutations of growth hormone (GH)-1 or the growth hormone releasing hormone receptor (GHRH-R) genes. Affected subjects present with symptoms of growth hormone deficiency (GHD) with low but detectable levels of growth hormone (GH), short stature and responsiveness to GH therapy. We describe a 13-month old girl with severe growth failure who showed a low GH response to two GH provocation tests and a modest increase of insulin-like growth factor-1 (IGF-1) to an IGF-1 generation test. Whole exome sequencing revealed a novel homozygous variant of the GHRH-R gene (c.97C>T), leading to a premature stop codon. Administration of recombinant human GH improved linear growth. This is the first report of a c.97C>T mutation of the GHRH-R gene.