Congenital central hypoventilation syndrome (CCHS) is inherited in an autosomal dominant manner. This means that having a change (mutation) in only one copy of the responsible gene in each cell is enough to cause features of the condition.
The genetics of CCHS can be complex. Most people with CCHS have a new (de novo) mutation in the responsible gene (the PHOX2B gene). De novo mutations occur for the first time in the affected person and are not inherited from a parent. Some people with CCHS have a parent with the condition, and inherit the mutation from that parent.
In some cases, an asymptomatic parent of a person with symptoms has a PHOX2B mutation in some of their germ cells (egg or sperm cells, not body cells). This is called germline mosaicism. Some of these parents also have a PHOX2B mutation in some of their body cells. This is called somatic mosaicism. Germline mosaicism with or without somatic mosaicism is present in about 25% of asymptomatic parents of people with CCHS.
Parents with mosaicism should have a comprehensive assessment to determine if any features of CCHS are present. It is also recommended that parents of a person with a presumed de novo mutation have genetic testing for the presence of the mutation, including testing that detects mosaicism at low levels.
Last updated: 1/12/2016
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