SHORT STATURE AND DECREASED SERUM GROWTH HORMONE-BINDING PROTEIN IN THE MOUNTAIN OK PEOPLE OF PAPUA-NEW-GUINEA

Two circulating GH-binding proteins (GH-BP), one of which is related to the GH receptor, have been described. To assess their possible role in or link with determining statural growth, we measured their activity/level in the serum of 25 adult subjects from a short-statured population from the highlands of Papua New Guinea (Mountain Ok people, similar in stature to African pygmies) and in 25 normal-statured North American control subjects. The Mountain Ok people have normal levels of GH, insulin-like growth factor-I (IGF-I), IGF-II, and serum albumin and prealbumin in association with short stature, making them a unique study population. Levels of the high affinity (GH receptor-related) GH-BP were significantly lower in the Mountain Ok subjects than in the taller controls (5.2 +/- 3.0% vs. 10.6 +/- 3.9% GH bound/160-mu-L, respectively; mean +/- SD; P < 0.001). In contrast, the low affinity GH-BP was comparable in Mountain Ok and control subjects. Because of the structural similarity between the GH receptor and GH-BP, these data suggest that a limitation in GH receptor/GH-BP endowment may be associated with short stature despite normal circulating IGF-I levels. Alternatively, it is possible that the GH-BP itself plays an important role in growth promotion. Thus, the GH receptor (and/or GH-BP) complement may be a determinant of the genetically programmed height achieved.