Genetic analysis of the PAPP-A2 gene and evaluation of free IGF-1, IGFBP-5, and ALS concentrations in a group of 22 patients with idiopathic short stature.

INTRODUCTION

Short stature is one of the main reasons for consultation in outpatient clinics and paediatric endocrinology departments and is defined as height below the 3rd centile or less than -2 standard deviations (SDs).

MATERIAL AND

METHODS

The study's overarching aim was to analyse the PAPP-A2 gene at mutation sites described to date and at exons 3, 4, and 5, which encode the fragment of the catalytic domain with the active site of the pregnancy-associated plasma protein A2 (PAPP-A2) protein. The secondary aims of the study were clinical and auxological analysis of a group of patients with idiopathic short stature and biochemical analysis of growth hormone-insulin-like growth factor-1 (GH-IGF-1) axis parameters not assessed as part of the routine diagnosis of short stature, such as free IGF-1, insulin-like growth factor binding protein 5 (IGFBP-5), and acid-labile subunit (ALS) levels. Molecular analysis of the PAPP-A2 gene was performed using polymerase chain reaction (PCR) and direct sequencing. Biochemical analysis of free IGF-1, IGFBP-5, and ALS was performed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The mean height standard deviation score (HSDS) in the study group was -2.95. None of the patients exhibited previously described mutations in the PAPP-A2 gene or mutations in exons 3, 4, and 5 encoding the fragment of catalytic domain with the active site of the PAPP-A2 protein. In 4 patients, the known, non-pathogenic, heterozygotic polymorphism c.2328C>T(rs10913241) in exon 5 was found.

CONCLUSIONS

Free IGF-1 levels correlate better with height and HSDS than total IGF-1 levels. The previously described mutations in the PAPP-A2 gene and mutations in exons 3, 4, and 5 encoding the fragment of catalytic domain with the active site of the PAPP-A2 protein were not detected; only the known and non-pathogenic, heterozygotic polymorphism c.2328C>T(rs10913241) in exon 5 of the PAPP-A2 gene was observed.