Mutations in the pregnancy-associated plasma protein A2 (PAPP-A2) gene have recently been shown to cause postnatal growth failure in two prepubertal patients from a non-consanguineous Spanish family due to the resulting decrease in IGF1 bioavailability.
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.
<b>Background:</b> Imatinib, a tyrosine kinase inhibitor, causes growth failure in children with chronic myeloid leukemia probably by targeting the growth hormone (GH)/insulin like growth factor-1 (IGF-1) axis.
Background Recombinant human insulin-like growth factor 1 (rhIGF-I) has been approved as an orphan drug for the treatment of growth failure in children and adolescents with severe primary IGF-I deficiency (SPIGFD) with little pharmacokinetic data available.
This review focuses on the most recent discovery: mutations in the metalloproteinase pregnancy-associated plasma protein-A2 (PAPP-A2), one of the proteases involved in liberating IGF-1 from the complexes in which it circulates, in patients with delayed growth failure.
Mutations in the PAPP-A2 gene have recently been shown to cause postnatal growth failure in humans, with specific skeletal features, due to the resulting decrease in IGF-1 bioavailability.
The results of the in-vitro study do not support the hypothesis that IGF-I/IGF-II resistance is a major pathogenetic mechanism responsible for the growth failure in the subgroup of SRS children with IGF2/H19 hypomethylation.
The phenotype includes reduced but not absent serum GH, with abnormal response to a variety of stimuli, and low serum insulin-like growth factor-1 levels, resulting in proportionate growth failure which becomes evident in the first year of life.
Two patients with a complete absence of biologically active IGF-1 showed severe pre- and postnatal growth, extreme microcephaly, sensorineural deafness and failure to thrive.
Genetic abnormalities causing growth failure that is less severe than the extreme phenotype are emphasized, together with an analysis of height and serum IGF-I across the spectrum of different types of GHR defects.
The spectrum of associated anomalies in this newly recognised phenotype complex consists of growth failure, typical facial anomalies with additional (previously unreported) nervous system abnormalities (e.g. sensorineural deafness) and somatomedin C deficiency.
During follow-up he manifested complications from the hydrocephalus and NDI including global developmental delay and growth failure with low IGF-1 and hypothyroidism.
A small number of children (to date 10) with modest growth failure and in the majority delayed puberty, a phenotype similar to that of CDGP, have been reported to carry mutations in the IGF acid labile subunit (IGFALS) gene which encodes the ALS, a part of the ternary complex carrying IGF-I in the circulation.
Finally, we clearly demonstrate that GH-R77C is not invariably associated with short stature, but that great care needs to be taken in ascribing growth failure to various heterozygous mutations affecting the GH-IGF axis and that careful functional studies are mandatory.