Abstract. Type I insulin-like growth factor receptor (IGF-IR) is widely expressed across many cell types in fetal and postnatal tissues. The activation of this receptor after the binding of secreted IGF-I and IGF-II promotes cell differentiation and proliferation. IGF-IR has an important role in normal fetal and postnatal growth and development. IGF-IR gene anomalies presenting with intrauterine and postnatal growth retardation have recently been reported in some families. Familial short stature with IGF-IR gene anomaly is considered rare, and the clinical condition and features remain unknown. IGF-IR gene anomaly such as heterozygous IGF-IR mutation or haploinsufficiency of the IGF-IR gene should be investigated in those patients presenting with 1) low birth weight and birth height (< -1.5 SD), 2) a familial history of low birth weight, 3) a normal or increased IGF-I level, 4) a normal or increased GH response to the GH stimulation test, and/or 5) less response to GH treatment than common small for gestational age (SGA) short-stature patients. In this review, we provide an overview of current knowledge of familial short stature with IGF-IR gene anomaly.Key words: Insulin-like growth factor (IGF), IGF-I receptor, Intrauterine and postnatal growth retardation, Short stature Type I insulin-like growth factor receptor (IGF-IR) is widely expressed across many cell types in fetal and postnatal tissues. The activation of this receptor after the binding of the secreted growth factor ligands IGF-I and IGF-II elicits a repertoire of cellular responses, including the proliferation and protection of cells from programmed cell death or apoptosis [1,2]. This signaling results in fetal somatic growth, whereas this postnatal somatic growth is achieved through the synergistic interaction of the growth hormone (GH) and IGFs. IGF-IR has an important role in normal fetal and postnatal growth and development [3,4].Intrauterine growth retardation is a common condition in newborns, in which fetal events constrain birth size, and 10-20% of children born small for their gestational age (SGA) remain short into adulthood. The birth weight of IGF-IR knockout mice is 45% of normal, but they die within minutes of birth due to respiratory failure [3,4]. Thus, it has been assumed that mutations in the IGF-IR gene are probably not a common cause of intrauterine growth retardation (IUGR) in humans [5]. However, recently heterozygous IGF-IR mutations presenting with intrauterine and postnatal growth retardation have been observed in10 families [6][7][8][9][10][11][12][13], including a patient we had previously reported [9]. In this review, we describe current knowledge of familial short stature with IGF-IR gene anomaly.
IGFs knock-out miceThe first paper from Liu JP, Baker J and colleagues revealed the essential role of IGFs in promoting fetal and postnatal growth by presenting the phenotype of igf1 - /-, igf2-/-, igf1r -/-, igf2r-/-[3, 4]. Mice lacking either the igf1 or igf2 genes exhibited intrauterine growth retardation, with weights approxi...