The presence of normal levels of serum immunoreactive insulin-like growth factor 2 (IGF-2) in patients with Down's syndrome.

The present study was performed to further investigate the levels of somatomedins in Down's syndrome (DS). The results show that the serum levels of immunoreactive insulin-like growth factor 2 (RIA-IGF-2) in patients with DS is within the normal adult range. No age variation among the patients was observed. Since we earlier reported a deficiency of immunoreactive insulin-like growth factor 1 (IGF-1) in DS patients, present study showing normal RIA-IGF-2 levels suggests a selective deficiency of IGF-1 in DS.