The little women of Loja - growth hormone-receptor deficiency in an inbred population of southern Ecuador

Article Abstract:

Investigators in Israel have previously defined a class of dwarfism that is caused by a defect in cell receptors for growth hormone. Receptors are the specialized biochemical structures found on the surface membranes of cells that bind with the hormone and induce its effect. Laron-type dwarfism (named for the researcher who described it) is identified in patients with small faces, depressed bridge of the nose, small jaws, and large heads; it occurs with equal frequency in males and females. The patients have defects of the hair and teeth, small hands and feet, and frequently have mental retardation. Similar reports of such patients have come from many parts of the world. The present report describes a group of 20 new patients living in Ecuador with a condition similar to Laron-type dwarfism, but they were noticeably distinct with regard to several features. These patients were short in stature, had blue scleras (the ''whites'' of the eyes appeared blue), and were usually female; none were intellectually retarded. These individuals were strongly interrelated, of Mediterranean origin (as are the Laron patients), and there was evidence of fetal death of males. Measurement of circulating growth hormone receptor molecules is thought to be indicative of a relative lack of cell-surface growth hormone-binding protein, which in turn results in a decreased ability of growth hormone to produce its effect. These patients had serum levels of growth hormone-binding protein that were only 1 to 30 percent of normal levels. This report is the first concerning a new type of dwarfism caused by a deficit in the quantity of growth hormone-binding protein, and related to the early fetal death of most affected males. (Consumer Summary produced by Reliance Medical Information, Inc.)

Abnormalities, Genetic aspects, Ecuador, Hormone receptors, Growth factor receptors, Dwarfism

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Broadening the growth hormone insensitivity syndrome

Article Abstract:

A 1995 study that sheds light on the genetic and biochemical aspects of certain unexplained growth disorders may affect diagnosis and treatment. Diagnosis of growth disorders is difficult because of the complex relationship between growth hormone (GH), GH receptors, and insulin-like growth factor (IGF) which is believed to trigger growth most directly. The 1995 study found that 4 of 14 short children with normal GH levels had mutations of the GH receptor that may have caused partial insensitivity to GH. The study suggests that growth deficits may be caused by GH receptor mutations on only one of a pair of genes. The study also may lead to methods of diagnosing these growth disorders by testing for growth IGF rather than GH. Effective therapies for children with partial insensitivity to GH may include IGF or large doses of GH.

Care and treatment, Editorial, Somatotropin, Somatotropin receptors

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Insulin-like growth factors and the basis of growth

Article Abstract:

A protein called insulin-like growth factor (IGF) appears to be involved in the growth of an unborn baby, as well as childhood growth. The only difference is that before birth, growth is not dependent on growth hormone, whereas after birth it is. A 2003 study found that two children who experienced intrauterine growth retardation had a mutation in the gene for the IGF receptor.

Physiological aspects, Fetal growth retardation, Insulin-like growth factor 1, Insulin-like growth factor I

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