Laron syndrome
Classification and external resources
Growth hormone
ICD-10	E34.3
ICD-9	259.4
OMIM	262500 245590
DiseasesDB	7262
eMedicine	ped/1277
MeSH	D046150

Laron syndrome, or Laron-type dwarfism, 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.

[edit] Eponym

It is named after Zvi Laron, the Israeli researcher who, with A. Pertzelan and S. Mannheimer, first reported the condition in 1966,^[1][2] based upon observations which began in 1958.^[3]

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.

[edit] Pathophysiology

Laron syndrome has an autosomal recessive pattern of inheritance.

Molecular genetic investigations have shown that this disorder is mainly associated with mutations in the gene for the GH receptor. These can result in defective hormone binding to the ectodomain or reduced efficiency of dimerization of the receptor after hormone occupancy. There are exceptionally low levels of insulin growth factor (IGF-1) and its principal carrier protein, insulin-like growth factor binding protein 3. This deficiency in IGF-1 is believed to provide the Ecuadorian Laron's with a full immunity to cancer.^[4]

A related condition involving postreceptor insensitivity to growth hormone has been associated with STAT5B.^[5]

[edit] Clinical characteristics

The principal feature of Laron syndrome is abnormally short stature (dwarfism). Physical symptoms include: prominent forehead, depressed nasal bridge, under-development of mandible, truncal obesity^[6] and a very small penis. Seizures are frequently secondary to hypoglycemia. Some genetic variations have an impact upon intellectual capacity.^[7]

The majority of reported cases have been of Mediterranean or Semitic origin, with numerous patients in Israel, Ecuador, Turkey and in the Bahamas.

[edit] Treatment

Administration of GH has no effect on IGF-1 production, therefore treatment is mainly by biosynthetic IGF-1.

[edit] Homo floresiensis

Recent publications have proposed that Homo floresiensis represented a population with widespread Laron syndrome.^[8][9]

[edit] References

[edit] External links

• MeSH Laron+syndrome