Trip Answers

Question answered:12/02/07 Warning! this question is over two years old.

We searched the NLH Specialist Libraries for Musculoskeletal Disease, and Clinical Genetics and the TRIP and Medline databases but found very little information to answer this question.

 

An e-Medicine article notes:

 

“Spondyloepiphyseal dysplasia (SED) is a descriptive term for a group of disorders with primary involvement of the vertebrae and epiphyseal centers resulting in a short-trunk disproportionate dwarfism. Spondylo refers to spine, epiphyseal refers to the growing ends of bones, and dysplasia refers to abnormal growth.” [1]

 

GPNotebook adds:

 

“The spondyloepiphyseal dysplasia family includes:
• achondrogenesis type II
• spondyloepiphyseal dysplasia congenita
• Kneist dysplasia
• Stickler syndrome.” [2]

 

Given that we do not know the form of spondyloepiphyseal dysplasia the patient has, we can only offer general information.

 

Parikh and Crawford discuss the genetic basis of SED and the likelihood of transmission of the gene for SED congenital and SED tarda:

 

• “Genetic basis of SED congenita
o SED congenita is transmitted as an autosomal dominant trait. The gene for  SED congenita has been mapped to the long arm of chromosome 12 (12q14.3). Gonadal mosaicism has been reported. Advanced paternal age is recognized as a risk factor.
o Most cases result from random new mutations. Average-sized siblings have no increased risk of producing a child with SED congenita. When both parents are affected, 50% of offspring are heterozygous and affected; 25% are homozygous, which is ordinarily fatal in the first few months of life; and 25% are unaffected. When one parent is affected, the chance of transmitting this gene to each child is 50%.

 

• Genetic basis of SED tarda
o SED tarda is genetically distinct from SED congenita. Although it may be transmitted as an X-linked recessive, autosomal recessive, or autosomal dominant trait, the X-linked recessive type is most common.
o The X-linked form has been mapped to the Xp22 region. Only males are affected, and mothers are carriers. Carrier females have a 25% risk of having an affected son, a 25% risk of having an unaffected son, a 25% risk of having a carrier daughter, and a 25% risk of having a noncarrier daughter. None of the sons of an affected male are affected; all daughters of an affected male are carriers. A case has been reported in which a girl with Turner syndrome had a diagnosis of SED tarda (Massa, 1989).” [1]

 

Given the lack of information on this topic, the NLH Q & A Service would suggest contacting a clinical genetics service for further assistance with this query.

 

References
1. Parikh S and Crawfrod A. Spondylo-epiphyseal dysplasia. E-Medicine. September 2003. (http://www.emedicine.com/orthoped/topic630.htm).
2. GPNotebook. Spondylo-epiphyseal dysplasia; types (http://www.gpnotebook.co.uk/simplepage.cfm?ID=-1502937011&linkID=31436&cook=yes).

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