LGS General Description.

The following is a general description of Langer-Giedion Syndrome (LGS), also known as Trichorhinophalangeal Syndrome Type II (TRPS2). It is not meant for diagnostic or medical purposes but to provide the general public with an basic understanding of this syndrome.

LGS is characterized by the following three features which are seen in almost all LGS cases:

• Cranio-facial abnormalities. These include large, laterally protruding ears, broad nasal bridge and bulbous nose, elongated upper lip with thin upper vermillion border, broad eyebrows, sparse hair and mild microcephaly.

• Multiple cartilaginous exostoses. These are bony growths projecting from the surfaces of various bones of the body.

• Cone-shaped epiphyses. The growing ends of certain bones, particularly in the hands, are coned shaped.

• Mental retardation.
  
• Shortness of stature.
  
• Overly flexible joints.
  
• Excess folds of skin.
  
• Others. (For a more complete list see NORD LGS or the OMIM clinical synopsis.

Langer-Giedion syndrome is characterized by chromosomal deletions associated with the long arm of chromosome 8. It is what scientists call a contiguous gene syndrome. This means that more than one gene within the same general chromosomal location is affected, and the each defective (or deleted) gene is responsible for a subset of the overall charcteristics. One of the genes known to be involved in LGS is hereditary multiple exostosis type 1 (EXT1). In addition to being associated with LGS, hereditary multiple exostosis is an independent disorder characterized by bony growths projecting outward from the surfaces of various bones of the body. A second gene known to be involved in LGS is tricho-rhino-phalangeal syndrome type 1 (TRPS1). TRPS1 is also an independent disorder characterized by the same cranio-facial abnormalities and cone shaped epiphyses seen in LGS. Therefore, a simple way of thinking of LGS is as a combined syndrome in which individuals have both EXT1 and TRPS1 (and perhaps others depending on specific characteristics.)

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