The Diagnostic Value of IGF-2 and the IGF/IGFBP-3 System in Silver-Russell Syndrome

Recently, we have described a family of 4 members presenting with intrauterine and postnatal growth failure, low IGF-2 levels, and signs of Silver-Russell syndrome (SRS) who carried a genomic IGF2 mutation. Here, we assess the value of IGF-2 in relation to SRS.

We collected data from 48 SRS children and 48 short children born small for gestational age (SGA) seen at our center. The SRS children were 4.6 ± 2.0 years of age, and the SGA children were 4.8 ± 1.8 years of age. All patients were prepubertal and growth hormone naive. An 11p15 ICR1 loss of methylation (11p15LOM) was present in 22, maternal uniparental disomy of chromosome 7 (upd(7)mat) in 7, and IGF2 genomic mutation (IGF2mut) in 3 patients. Growth factors were measured by in-house radioimmunoassays.

The median IGF-2 standard deviation scores (SDSs) were: IGF2mut -1.75, upd(7)mat -1.69, nonsyndromic SGA -1.52, 11p15LOM -0.61, and clinical (tested negative) -0.55. The median IGF-2:IGF-1 concentration ratio was 2.57 in IGF2mut compared to 5.44 in 11p15LOM (p = 0.036), 7.84 in clinical, and 7.98 in upd(7)mat. Upd(7)mat patients had significantly lower IGF-1 and IGFBP-3 SDSs than patients with 11p15LOM (p ≤ 0.002).

Serum IGF-2 in combination with IGF-1 and IGFBP-3 can add to the clinical signs of SRS patients and help to perform targeted genetic testing. Further studies are needed.