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Laron Syndrome

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Jill Castle

on 6 May 2010

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Transcript of Laron Syndrome

Laron Syndrome What is Laron Syndrome?

What are the symtoms?

Who is Laron Syndrome named after and when was it discovered?

More about it:


Administration of GH has no effect on IGF-1 production, therefore treatment is mainly by biosynthetic IGF-1.
Blue sclera
High-pitched voice
Delayed menarche
Childlike proportions in adults
Proportionally larger head
Limited elbow extension
Reduced intelligence
Superior intelligence
Short stature
Delayed bone age
High level of circulating growth hormone
Low blood sugar level
Delayed tooth eruption
Saddle nose
Deep-set eyes
Abnormal skull growth
Delayed sexual development
Small hands
Small feet
Obesity Laron syndrome is a rare human genetic disease that causes dwarfism. People with Laron syndrome lack certain receptors important for body growth. They have normal levels of growth hormone produced by the pituitary gland, but without the cell receptors, the hormone is unable to bind to cells and promote growth.

In other words:
Laron Syndrome is an autosomal recessive disorder characterized by an insensitivity to growth hormone (GH), caused by a variant of the growth hormone receptor. It causes short stature.
It is named after Zvi Laron, the Israeli researcher who, with A. Pertzelan and S. Mannheimer, first reported the condition in 1966, based upon observations which began in 1958.
Resistance to GH was first reported by Laron in 1966. Since then, severe resistance to GH, characterized by grossly impaired growth despite normal levels of GH in serum, has been termed Laron syndrome. Laron dwarfism is associated with resistance to growth hormone (GH). To investigate its genetic basis, scientist used genetic linkage to test whether the disorder results from a defect in the gene for the human GH receptor. Denaturing gradient gel electrophoresis and sequencing of specific GH-receptor-gene fragments allowed us to characterize specific intragenic DNA markers in 35 control subjects of Mediterranean descent, for use in linkage studies. In two Mediterranean families in which the parents were consanguineous and some of the children had Laron dwarfism, the disease trait and DNA polymorphisms were inherited together. Moreover, an analysis of the GH-receptor-gene RNA transcripts in lymphocytes from one of these families allowed us to identify a thymidine-to-cytosine substitution that generated a serine in place of a phenylalanine at position 96 in the extracellular coding domain of the mature protein. This defect probably affects the receptor adversely and is probably responsible for the lack of plasma GH-binding activity in the patients. This mutation was not found in the GH-receptor genomic sequences of seven unrelated subjects with Laron dwarfism who belonged to different population groups. An analysis of the GH-receptor markers in these patients indicated that different gene frameworks (polymorphic sites within the single gene) were associated with the mutant alleles. scientist conclude that Laron dwarfism is due to abnormalities in the gene for GH receptor, which may differ from family to family.
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