How is spondyloepiphyseal dysplasia congenita inherited?
Spondyloepiphyseal dysplasia (SEDC) is typically inherited in an autosomal dominant manner. This means that one altered (mutated) gene in each cell is sufficient to cause the disorder. Most cases of SEDC do not result from inheriting it from a parent, however; the condition more commonly results from a random, new mutation in the gene occurring for the first time in an affected individual who does not have a history SEDC in the family. In most of these cases, the risk to have another child with the condition is comparable to the risk for an individual in the general population to have a child with the condition. A few cases of autosomal recessive forms of SEDC have been reported.
Germline mosaicism has also been reported for this condition. In this case, the parent does not have the mutated gene in all the cells of the body (and is not affected), but only in some of the germ cells (sperm or egg cells). The recurrence risk for a parent with germline mosaicism to have another affected child is difficult to predict. For conditions with autosomal dominant inheritance, studies have demonstrated that the risk to have another affected child may be low (about 1%), moderate (about 6%), or higher (about 30%), depending on the proportion of germ cells with the mutation as well as the disorder itself.
Last updated: 1/11/2012
What are the chances of having a second child affected with spondyloepiphyseal dysplasia congenita?
The recurrence risk for spondyloepiphyseal dysplasia congenita (SEDC) varies depending on the mode of inheritance of the condition in each family. In the case that the condition resulted from a random, new, autosomal dominant mutation in an affected individual (which occurs most commonly), the risk to have another affected child is theoretically close to that of the general population (1 per 100,000 live births). However, there have been a few instances in which parents with an affected child were counseled in accordance with this risk and then had a second affected child. It is not known if these cases were due to the children actually having an autosomal recessive form of the condition, or if germline mosaicism was present in one of the parents. In the case that a parent has germline mosaicism (which may not be known), the risk depends on the proportion of germ cells that have the mutated disease-causing gene. If a parent is affected with the condition, the risk for each child to be affected is 50% (1 in 2).
It is recommended that individuals who have specific questions about their personal family history and/or recurrence risks consult with a genetics professional.
Last updated: 1/11/2012
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