Genetic factors associated with small for gestational age birth and the use of human growth hormone in treating the disorder

Table 2 Phenotypic characteristics and response to hGH therapy for patients with IGF-1 mutations

Genetic mutation	Phenotype	GH response	Ref.
Deletion of exons 4 and 5	Birth weight −3.9 SD; birth length −5.4 SD; sensorineural deafness and mental retardation; nearly undetectable IGF-1 levels	−	Woods, 1996 [11]
Truncated version of exon 6	Birth weight −4 SD; birth length −6.5 SD; sensorineural deafness and mental retardation; low serum IGF-1 levels	−	Bonapace, 2003 [13]
V44M	Birth weight −3.9 SD score; birth length −4.3 SD score; bilateral hearing loss, microcephaly, severe mental retardation; elevated GH levels and IGF-1 levels but normal IGFBP-3 levels	n.a.	Walenkamp, 2005 [16] Denley, 2005 [17]
R36Q	Birth weight −2.5 SD score; birth length −3.7 SD score; mild mental development delay; reduced IGF-1 levels but increased IGFBP-3 levels	+	Netchine, 2006 [18]

hGH, human growth hormone; IGF-1, insulin-like growth factor-1; IGFBP-3, insulin-like growth factor binding protein-3; n.a., not available; SD, standard deviation.

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