In-vitro Ternary Complex Formation (ivTCF) Enhanced by the Addition of IGFBP-3 (TCF+): A Useful Approach for the Assessment of the Function of Human IGFALS Gene Variants

HORACIO M. DOMENE; PAULA A. SCAGLIA; LILIANA KARABATAS; ANA C. KESELMAN; ALICIA S. MARTINEZ; DEBORA BRASLAVSKY; SONIA V. BENGOLEA; VIVIANA PIPMAN; IGNACIO BERGADA; HECTOR G. JASPER

San Francisco

Congreso; 95th. Annual Meeting of the Endocrine Society; 2013

The Endocrine Society

Background: Acid labile subunit (ALS) is crucial for ternary complex formation and therefore, to sustain circulating IGF-I levels. While complete ALS deficiency (ALS-D) is characterized by mild short stature and severe circulating IGF-I and IGFBP-3 deficiencies, first degree relatives, heterozygous carriers for IGFALS gene mutations (HC-FDR), present height, IGF-I and IGFBP-3 levels in between ALS-D and wild type (WT) relatives, suggestive of a gene-dosage effect. In addition, IGFALS genetic variants have been reported in a subgroup of idiopathic short stature (ISS) children. Objective: The aim of the present study was to assess functional ability for ivTCF in children affected by different degrees of ALS insufficiency. Subjects and Methods: Levels of IGF-I and ALS were assessed by RIA, IGFBP-3 by CLIA, ivTCF by size exclusion chromatography (Sephacryl S200) both before (TCF#) and after (TCF+) the addition of rhIGFBP-3 (6 µg/ml) and expressed as: (area under the curve/total area)x100. IGFALS gene was completely sequenced. Patients: 7 ALS-D, 7 HC-FDR, 15 prepuberal ISS and 5 prepuberal (PP) and 5 puberal (P) normal controls. ISS children were divided in 3 groups according to IGFALS genotype (HC for allelic variants of IGFALS gene or WT) and levels of IGF-I (normal or low,